sign in sign up
<<
Home , Ceramic knife, Chemical milling, Electromagnetic forming, Metal spinning, Transfer molding

Making It

LK016_P0001EDmakingIt2us.indd 1 16/09/2011 13:35 LK016_P0001EDmakingIt2us.indd 2 16/09/2011 13:35 Making It

Manufacturing Techniques for Product Design

Laurence King Publishing

LK016_P0001EDmakingIt2us.indd 3 16/09/2011 13:35 Contents

6 Introduction 10 Comparing Processes 1 Cut from 18 21 Computer Numerical For Jerome, our treasure Control (CNC) Cutting 24 Electron-Beam Machining (EBM) 26 29 Jiggering and Jollying 33 Plasma-Arc Cutting

2 Sheet 38 Chemical 40 Cutting 42 Water-Jet Cutting 44 Wire EDM (Electrical Copyright © 2012 Central Saint Martins College Discharge Machining) of Art & Design, The University of the Arts London and Cutting First published in Great Britain in 2007. 46 Second edition published 2012 by Laurence King 48 Oxyacetylene Cutting Publishing in association with Central Saint 50 Sheet-Metal Martins College of Art & Design 52 Slumping Glass 54 Electromagnetic This book has been produced by Forming Central Saint Martins Book Creation, 56 Metal Southampton Row, London WC1B 4AP, UK 59 Metal Cutting 61 Industrial ® Laurence King Publishing Ltd 64 361–373 City Road 67 London EC1V 1LR 70 Superforming Aluminum United Kingdom 73 Free Internal Pressure- Tel: + 44 20 7841 6900 Formed Steel Fax: + 44 20 7841 6910 76 Inflating Metal e-mail: [email protected] 78 Pulp www.laurenceking.com 80 Bending Plywood 83 Deep Three-Dimensional All rights reserved. No part of this publication Forming in Plywood may be reproduced or transmitted in any form or 86 Pressing Plywood by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without prior permission in 3 Continuous writing from the publisher. 90 Calendering 92 Blown Film A catalog record for this book is available 94 Exjection from the British Library 96 ® 99 ISBN: 978-1-85669-749-1 102 PulshapingTM 104 Roll Forming Design: Roger Fawcett-Tang, Struktur Design 106 Rotary Cover design: Marianne Noble 108 Pre- Senior editors: Peter Jones, 112 Veneer Cutting Jessica Spencer (2007 edition) Picture research: Jennifer Hudson, Lucy Macmillan Printed in China

LK016_P0001EDmakingIt2us.indd 4 16/09/2011 13:35 4 Thin & Hollow 6 Complex 8 Finishing 116 Glass Blowing by Hand 196 Injection Techniques 118 Lampworking Glass Tube 199 Reaction Injection 262 Sublimation Dye Printing 120 Glass Blow and Molding (RIM) Vacuum Metalizing 201 Gas-Assisted Injection 263 Flocking 124 Glass Press and Molding Acid Blow Molding 203 Mucell Injection Molding 264 Laser 127 Blow Molding 206 Insert Molding Screen Printing 129 Injection Blow Molding 209 Multishot Injection 265 Electropolishing 132 Extrusion Blow Molding Molding Tampo Printing 134 Dip Molding 212 In-Mold Decoration 266 Suede Coating 137 214 Over-Mold Decoration Hot Foil Blocking 140 Slip 216 Metal Injection Molding 267 Over-Molding 143 Metal (MIM) Sandblasting 146 Backward Impact Extrusion 219 High-Pressure Die-Casting 268 i-SD System 149 Molding Paper Pulp 222 Ceramic Injection Molding In-Mold Decoration 152 Contact Molding 224 269 Self-Healing Coating 154 Vacuum Infusion Process 228 Liquid-Repellent Coatings (VIP) 231 Pressing Glass 270 Ceramic Coating 156 Autoclave Molding 234 Pressure-Assisted Slip Powder Coating 158 Casting 271 Phosphate Coatings 161 Centrifugal Casting 236 Viscous Plastic Processing Thermal Spray 164 Electroforming (VPP) 272 Case Hardening High-Temperature Coatings 273 Thick-Film Metalizing 5 Into Solid 7 Advanced Protective Coatings 168 240 Inkjet Printing 274 Shot 170 Hot Isostatic Pressing (HIP) 242 Paper-Based Rapid Plasma-Arc Spraying 172 Cold Isostatic Pressing (CIP) Prototyping 275 Galvanizing 174 244 Contour Crafting Deburring 176 Transfer Molding 246 Stereolithography (SLA) 276 Chemical Polishing 178 Foam Molding 250 Electroforming for Vapor Metalizing 181 Foam Molding into Micro-Molds 277 Decalization Plywood Shell 252 Selective Laser Sintering Pickling 184 Inflating Wood (SLS) 278 Nonstick Coating (organic) 187 255 Smart ™ for Nonstick Coating (inorganic) 190 Powder Forging Filament Winding 279 Chrome 192 Precise-Cast Prototyping 257 Incremental Sheet-Metal Anodizing (pcPRO ®) Forming 280 Shrink-Wrap Sleeve Dip Coating 281 Ceramic Glazing Vitreous Enameling

282 Glossary 284 Index 287 Acknowledgments 288 Picture Credits

LK016_P0005EDmakingIt2us.indd 5 09/11/2011 13:33 6 Introduction Introduction

We are drawn to the unknown, to have been many innovations in the world uncovering secrets, and to unearthing the of production, a selection of which has unseen nature of the modern world—from been added to this new updated edition. childhood TV shows that peer through Some are highly specialized, such as the windows of factories looking at lines , some are old of chocolate cookies and milk bottles methods re-evaluated, such as Industrial being made, to cottage industries that Origami®, and others combine two reveal to tourists the production methods processes, such as Exjection®, a method of of indigenous craftsman, even down to making that combines injection molding DVD “bonus features” that entertain us and extrusion. There have also been some with how filmmakers cheat reality with notable uses of established production special effects. Designers in particular methods, such as Marcel Wanders’ are constantly looking for new ways to Sparkling Chair, which upscales injection transform both old and new technologies blow molding from the and to apply them within the design arena. industry and applies it to the making of The invention of machines that are a piece of furniture. used to turn out two thousand lightbulbs There is a growing momentum for per minute or ultrafine flexible optic a more sustainable approach to design. In cables has always amazed me and how order to address the increasing importance they came into being. What kind of creative of energy use, material scarcity, and ethical mind would have conceived the process production I have also added details that that requires hot, sticky, molten glass to will give the reader an introduction to some be suspended from a tower and dropped at of these complex areas and key points of a slow rate, stretching into tubes of glass consideration. In addition there is also a 1 less than /25 inch thick to create an optical major new section on finishing techniques, glass fiber; or that contorts steel wire into as one of the most common ways is to the iconic Gem paper clip at a rate of 300 innovate by coloring, painting, spraying, per minute; or the process that makes growing, or adding functionality to a glass marbles with those swirly patterns component. The chart on pages 10 to 13 of color, each with its own ? But provides an at-a-glance overview of major these uniquely formed products are each factors such as volumes of production and specific to their own production process cost for each technique that will give the and are for another book. Instead this book reader a straightforward comparison presents those methods that are relevant and quick reference guide to these key to the production of any given object, pieces of information. in a nutshell those that are relevant to As stated, the aim of this book is to industrial design. explore the hidden side of objects within Since the publication of the highly the context of industrial design. To peer successful first edition of Making It there into the world of machines and the often

LK016_P0001EDmakingIt2us.indd 6 16/09/2011 13:35 Introduction 7

creative and inspired ways that they have also including some of the more offbeat been assembled to morph liquids, , processes that perhaps don’t really fit into sheets, powders, and hunks of metal into the realm of the mass-produced object but three-dimensional products. To examine help point the way to a new direction, ideas these pieces of theater in a way that has that take a type of industrial production not been presented before in a book. To and combine it with a craftlike approach, try and communicate what is an inherent projects that take small-scale, widely playfulness that is evident in mass available machines and reuse them. production. To encourage the abduction Before the Industrial Revolution the of some of these methods by designers crafting of objects was often influenced to make better products and to exploit by surrounding geography. Ceramics, production as part of the creative process for example, were designed and made rather than as a means to an end. in areas where there was an abundance My intention was to take all the of clay, such as Stoke-On-Trent in the information that exists in technical northwest of England, the birthplace of manuals, trade journals, and websites Wedgwood and countless other ceramics for associations and federations in the factories. Places with large areas of engineering sectors and to encapsulate woodland often had communities that it in a guide for the designer that would specialized in furniture production. Skills be a relevant introduction to the world and materials came from specific local of the manufactured object. In one sense resources. The economy has had to celebrate all the relevant methods of consequences for local resources and has mass- and batch production for the three- often destroyed communities, but now dimensional object at this particularly technology is taking production back to important crossroads in the evolution of the small-scale craft user and placing it in objects. This is a time when old ideas of the hands of the consumer. Sometimes this manufacturing are being re-evaluated by is intentional and driven by new products the design industry and new possibilities and technology, at other times it is driven are surfacing, which have the potential by people abducting machines and using to alter dramatically the way we make, them for something for which they were choose, and consume our products. It used not intended. The adaptation of the to be the case that design was the slave humble inkjet printer for rapid prototyping to manufacturing, restricting creativity, is one such example. molding constraints and costs. In many The reuse of this type of product cases this is still true but increasingly or technology is a vital part of evolution: manufacturing is seen as a tool for experimenting, mixing things up, designing new opportunities to bring and swapping them around, turning new materials and ideas to new methods existing conventions on their head. Our of production, and to experiment with insatiable appetite for making things preconceived volumes of production. races ahead at full speed. But if the old Some of the examples featured in tools of craftsmanship were hand tools this book reflect a stage of development for shaping materials then the new tools where the new tools of designers and of the craftsman are the machines. For makers are not physical tools but factory around $100 you can buy an inkjet printer, setups. Take, for example, Malcolm take out the guts, and start playing with Jordan’s Curvy Composites, a degree-show the workings and use CAD-driven data design project that resulted in a completely to produce a whole range of new things. new way of forming wood. I couldn’t resist When people first started making “things”

LK016_P0001EDmakingIt2us.indd 7 16/09/2011 13:35 8 Introduction

they picked a lump of wood, understood How to use this book its properties to a certain degree, and The book is divided into sections based were able to chop it into a usable product. on the shapes of components that can For some, the lump of wood has become be produced with each process. It does the inkjet printer, a piece of technology not set out to answer all the questions that has been chopped up and generally you might ever need to know about these messed about with to create a multitude methods but does provide a clear and of products. basic introduction, using a combination of Possibly one of the most unusual text, illustrations, and photographs of the technologies of this kind is that which products. The visual explanations provided has been developed by various teams of in the diagrams serve to encapsulate the scientists across the world using “modified principles of the process and the steps that inkjet printers” to build up living tissue. go into making a final component. They Based on the long-held knowledge that are not meant to be accurate drawings of when placed next to one another, cells the machines. will weld together, the tissue is built up The text for each feature is broken using a thermo-reversible gel as a kind of down into two main forms to provide a scaffolding over each cell. A team from summary of the particular process and a the Medical University of South Carolina secondary list of the key points that relate uses this gel as a way to support the cells to the process. as they are being distributed. This gel is interesting in itself, designed to change Pros and cons instantly from liquid to gel in response to a These are bullet-pointed notes that stimulus such as increase in temperature. summarize each production method to This would allow tissue to be placed inside provide a quick guide to key features. the body supported by the gel; the gel would then dissolve. Volumes of production The of this book, however, deals This explains the range of unit volumes with mass-production techniques, some that different methods are capable of, well established, others very new. In order from one-off rapid prototyping to single for these tools to be used, they need to production runs in the hundreds be understood in all their forms and to be of thousands. presented in a manner that is relevant to design, stimulating ideas and allowing Unit price vs. capital investment for new creative connections to be made, One of the main criteria for specifying a connections that could provoke the particular method of production is knowing reappropriation of a technology into a new the initial investment that is required. This area or industry. The structure and layout can vary enormously from plastic forming of this book are straightforward and allow methods, such as the various forms of for a casual toe-dipping into the world injection molding, which potentially can of the manufactured object, hopefully run into tens of thousands of dollars, to to inform and inspire a fresh look and a CAD-driven methods, which require no greater understanding of the backstage tooling and minimal setup costs. arena of the world of consumerism.

LK016_P0001EDmakingIt2us.indd 8 16/09/2011 13:35 Introduction 9

Speed Relevant materials Speed is an important factor in This is a list of the types and range of understanding the scale of production and materials that can be formed with the how many units can be produced over a featured process. period of time. If, for example, you want to make 10,000 glass bottles, then the Typical applications automated glass blow molding process, A list of products and industries that which can produce 5,000 pieces per hour, is typically utilize the method of production, not for you, as the setup and tooling would the word “typically” has to be emphasized prohibit such a short production time on as the list is not exhaustive but gives the machines. sufficient examples to help explain the process. Surface This briefly describes the type of surface Similar methods finish that you can expect from a particular This provides a key to other processes process. Again this can vary enormously featured in the book that might be looked and indicates whether a part would need at as an alternative form of production to a secondary process in order to arrive at a the one featured. finished part. Sustainability issues Types/complexity of shape A very brief overview of some of the This offers guidance on any restrictions key points that fall into the area of that will affect the shape of the component sustainability. This will allow the reader and any design details to consider. to make more informed decisions on areas such as energy use, toxic chemicals, and Scale material wastage. This gives an indication of the scale of the products that can be produced from the Further information particular process. Sometimes this can This lists resources to visit for further offer some surprising facts, for example information. These include contributors to some metal spinners can spin metal sheets the book. Any relevant associations, where up to 11½ feet in diameter. available, are also listed.

Tolerances The degree of accuracy that a process is capable of achieving is often determined by the material. Machine-cut metals or injection-molded , for example, are capable of highly controlled tolerances. Certain ceramic processes, on the other hand, are much less able to achieve precise finished dimensions. This section gives examples of this accuracy.

LK016_P0001EDmakingIt2us.indd 9 16/09/2011 13:35 10 Comparing Processes Comparing Processes

The chart that runs over the next few pages will enable you to compare different processes and evaluate which is best for your own product. Processes are listed according to chapter type and in the same order as they appear in the relevant chapter. See the chapter entry for further details.

Key: c= low Cost of Number of Quality of cc= mid capital components ccc= high investment produced per hour

1. Cut from Solid Machining c c / cc ccc Computer (CNC) Cutting c c / cc ccc

Electron-Beam Machining (EBM) cc c c

Turning c c / cc cc

Jiggering and Jollying c cc / ccc ccc Plasma-Arc Cutting c cc / ccc ccc (edge surface finish)

2. Sheet c ccc cc Die Cutting cc cc cc (edge surface finish) Water-Jet Cutting c c / cc cc (edge surface finish) Wire Electrical Discharge Machining (EDM) c c / cc cc Laser Cutting c c / cc cc (wood) / ccc (metal) Oxyacetylene Cutting c cc cc Sheet-Metal Forming cc / ccc c / cc c Slumping Glass ccc c ccc Electromagnetic Steel Forming ccc ccc ccc cc c / cc c Metal Cutting cc ccc c Industrial Origami® c / cc / ccc c / cc / ccc ccc Thermoforming c / cc / ccc c / cc / ccc cc (depends on mold) Explosive Forming cc c / cc / ccc cc Superforming Aluminum ccc cc ccc Free Internal Pressure-Formed Steel c cc cc Inflating Metal c cc ccc Pulp Paper ccc c c Bending Plywood cc / ccc c / cc / ccc c / cc / ccc (depends on wood) Deep Three-Dimensional Forming in Plywood ccc ccc c Pressing Plywood cc c ccc

LK016_P0001EDmakingIt2us.indd 10 16/09/2011 13:35 Comparing Processes 11

Type of shape Size Degree of Relevant materials tolerance

Solid complex S, M, L ccc Wood, metal, plastic. glass, ceramics Solid complex. Any shape that S, M, L ccc Virtually any material can be produced on CAD Solid complex. Any shape that S, M ccc Virtually any material (high melting temperatures can be produced on CAD slow down process) Symmetrical S, M ccc (metal) Ceramic, wood, metal, plastic cc (other) Solid S, M c Ceramic Sheet S, M, L cc Electrically conductive metal

Sheet S, M ccc Metal Sheet S, M ccc Plastic Sheet S, M, L cc Glass, metal, plastic, ceramic, stone, marble Sheet S, M, L ccc Conductive metal Sheet S, M ccc Metal, wood, plastic, paper, ceramic, glass Sheet S, M, L cc Ferrous metals, titanium Sheet S, M, L cc Metal Sheet S, M, L c Glass Sheet ccc Magnetic metals Sheet S, M, L c Metal Sheet S, M, L ccc Metal Sheet / Complex S, M, L ccc Metal, plastic, composites Sheet S, M, L cc Complex S, M, L ccc Metal Sheet / Complex S, M, L cc Superelastic aluminum Hollow M, L c Metal Sheet S, M, L ccc Metal, plastic Sheet M, L c Paper Sheet M, L c Wood Sheet S, M c Wood veneer Sheet S, M N/A Wood veneer

LK016_P0001EDmakingIt2us.indd 11 16/09/2011 13:35 12 Comparing Processes

Key: c= low Cost of Number of Quality of surface finish cc= mid capital components ccc= high investment produced per hour

3. Continuous Calendering ccc ccc ccc Blown Film ccc ccc ccc Exjection® ccc ccc ccc Extrusion c c ccc

Pultrusion cc c cc

Pulshaping™ cc ccc cc

Roll Forming ccc ccc ccc

Rotary Swaging c cc / ccc ccc Pre-Crimp Weaving c c / cc / ccc cc

Veneer Cutting N/A N/A cc

4. Thin & Hollow Glass Blowing by Hand c / cc / ccc c / cc ccc Lampworking Glass Tube c c / cc / ccc ccc Glass Blow and Blow Molding ccc cc / ccc ccc Glass Press and Blow Molding ccc cc / ccc ccc Plastic Blow Molding ccc ccc ccc (parting lines remain) Injection Blow Molding ccc ccc ccc Extrusion Blow Molding ccc c ccc Dip Molding c cc / ccc c Rotational Molding cc cc / ccc cc Slip Casting c / cc c / cc / ccc cc (depends on number of components) Hydroforming Metal ccc ccc c / cc (depends on material) Backward Impact Extrusion c c / cc cc Molding Paper Pulp ccc ccc c

Contact Molding ccc c cc / ccc (depends on method)

Vacuum Infusion Process (VIP) cc c ccc Autoclave Molding cc cc c / cc (if gel is applied) Filament Winding c c / cc / ccc cc (finishing required) Centrifugal Casting c / cc / ccc c / cc c / cc (depends on process) (depends on mold material) Electroforming c c ccc

LK016_P0001EDmakingIt2us.indd 12 16/09/2011 13:35 Comparing Processes 13

Type of shape Size Degree of Relevant materials tolerance

Sheet L N/A Textile, composite, plastic, paper Sheet / Tube L ccc LDPE, HDPE, PP Continuous / Complex S, M, L ccc Wood, plastic, metals Sheet / Complex / Continuous M, L ccc Plastic, wood-based plastic, composites, aluminum, , ceramic Any shape of constant thickness S, M, L ccc Any thermoset plastic combined with glass and carbon fiber Variety of extruded L ccc Thermosetting resins with glass, cross sections, continuous carbon, or aramid fiber Sheet M, L cc / ccc Metal, glass, plastic (depends on thickness) Tube S, M cc Ductile metals Sheet M, L N/A Any weavable alloy, mainly stainless or galvanized steel Sheet / Continuous M, L N/A Wood

Any S c Glass Symmetrical S, M c Borosilicate glass Simple forms S, M c Glass Simple forms S, M cc Glass Simple rounded forms S, M, L ccc HDPE, PE, PET, VC Simple forms S ccc PC, PET, PE Complex S, M cc PP, PE, PET, PVC Soft, flexible, simple forms S, M c PVC, latex, , elastomers, silicones Any S, M, L c PE, ABS, PC, NA, PP, PS Ranging from simple S, M c Ceramic to complex Tube, T-sections S, M, L ccc Metal Symmetrical S, M ccc Metal Complex S, M, L cc / ccc Paper: newspaper and cardboard (depends on process) Open, thin cross-sections S c Carbon, aramid, glass and natural , thermosetting resin Complex M, L c Resin, fiberglass Simple S, M, L c Fiber and thermoset polymers Hollow, symmetrical L ccc Fiber and thermoset polymers Tubular S, M, L ccc Metal, glass, plastic (depends on process) Complex S, M, L ccc Electroplatable alloys

LK016_P0013EDmakingIt2us.indd 13 09/11/2011 13:33 14 Comparing Processes

Key: c= low Cost of Number of Quality of surface finish cc= mid capital components ccc= high investment produced per hour

5. Into Solid Sintering cc / ccc cc ccc Hot Isostatic Pressing (HIP) cc c ccc Cold Isostatic Pressing (CIP) cc c cc Compression Molding cc ccc ccc Transfer Molding cc / ccc ccc ccc Foam Molding ccc ccc c Foam Molding into Plywood Shell cc cc N/A Inflating Wood c c N/A Forging c / cc / ccc c / cc / ccc c Powder Forging ccc cc / ccc cc Precise-Cast Prototyping (pcPRO®) c c c

6. Complex Injection Molding ccc ccc ccc Reaction Injection Molding (RIM) ccc cc ccc Gas-Assisted Injection Molding ccc ccc ccc Mucell Injection Molding ccc ccc ccc Insert Molding ccc ccc ccc Multishot Injection Molding ccc ccc ccc In-Mold Decoration ccc ccc ccc Over-Mold Decoration ccc ccc ccc Metal Injection Molding (MIM) ccc cc ccc High-Pressure Die-Casting ccc ccc ccc Ceramic Injection Molding ccc cc ccc Investment Casting ccc cc ccc Sand Casting c cc c Pressing Glass cc ccc cc Pressure-Assisted Slip Casting ccc ccc ccc Viscous Plastic Processing (VPP) ccc ccc ccc

7. Advanced Inkjet Printing c c cc Paper-Based Rapid Prototyping c c c Contour Crafting c c c Stereolithography (SLA) c c c Electroforming for Micro-Molds c ccc ccc Selective Laser Sintering (SLS) c c c Smart Mandrels™ for Filament Winding cc c N/A Incremental Sheet-Metal Forming c cc ccc

LK016_P0001EDmakingIt2us.indd 14 16/09/2011 13:35 Comparing Processes 15

Type of shape Size Degree of Relevant materials tolerance

Complex / Solid S, M cc Ceramic, glass, metal, plastic Complex / Solid S, M, L cc Ceramic, metal, plastic Complex / Solid S, M cc Ceramic, metal Solid S cc Ceramic, plastic Complex / Solid M, L ccc Composite, thermoset plastics Complex / Solid S, M, L cc Plastic Solid M, L cc Wood, plastic Solid M, L cc Wood, plastic Solid S, M, L c Metal Complex / Solid S, M, L cc Metal Complex / Solid S ccc Plastic

Complex S, M ccc Plastic Complex S, M, L ccc Plastic Complex / Solid S, M, L ccc Plastic Complex S, M, L ccc Plastic Complex S, M ccc Plastic, metal, composite Complex S, M ccc Plastic Complex S, M ccc Plastic, metal, composite Complex S, M ccc Plastic, metal, composite Complex S, M ccc Metal Complex S, M, L ccc Metal Complex S, M ccc Ceramic Complex S, M, L ccc Metal Complex S, M, L c Metal Hollow S, M, L ccc Glass Hollow S, M, L cc Ceramic Complex S, M, L cc Ceramic

Sheet S ccc Other Complex S ccc Other Complex L ccc Ceramic, composite Complex S, M ccc Plastic Flat S ccc Plastic Complex S, M ccc Metals, plastics Hollow S, M, L cc Plastic Sheet S, M, L c Metal

LK016_P0001EDmakingIt2us.indd 15 16/09/2011 13:35 1: Cut fro Solid

18 Machining 21 Computer Numerical Control (CNC) Cutting 24 Electron-Beam Machining (EBM) 26 Turning 29 Jiggering and Jollying 33 Plasma-Arc Cutting

LK016_P0016EDmakingIt2us.indd 16 16/09/2011 13:40 Cut from Solid: 17 o m

The use of cutting tools to sculpt materials

This chapter encompasses some of the oldest processes used in the manufacture of objects, and these processes can be quite simply categorized by the fact that they use tools that cut away, shape, and remove material. Increasingly, the “brutal” part of these processes is being performed by automated CAD-driven machines, which carve effortlessly through most materials, providing yet another avenue for the exploitation of rapid prototyping technology and the replacement of the craftsman who gave life to many products throughout history.

LK016_P0016EDmakingIt2us.indd 17 16/09/2011 13:40 18 Cut from Solid: Machining Machining including turning, , , , reaming, milling, and

Machining belongs to a branch of production that falls under the commonly used umbrella term “chip-forming” (meaning any cutting technique that produces “chips” of material as a result of the cut). All machining processes have in common the fact that they involve cutting in one form or another. Machining is also used as a post-forming method, as a finishing method, and for adding secondary details such as threads. The term “machining” itself embraces many different processes. These include several forms of operation for cutting metals, such as turning, boring, facing, and threading, all of which involve a cutter being brought to the surface of the rotating material. Turning (see also p.20) generally refers to cutting the outside surface, while boring refers to cutting an internal cavity. Facing uses the cutter to cut into the flat end of the rotating work piece. It is used to clean up the end face, but the same tool can be used to remove excess material.

Product Mini Maglite® torch Designer Anthony Maglica Materials aluminum Manufacturer Maglite Instruments Inc. Country USA Date 1979

The Maglite® torch, with its highly distinctive engineered aesthetic, has been produced using a number of metal chip-forming techniques, notably turning. The textured pattern for the grip, however, is produced post forming using a process known as knurling.

LK016_P0016EDmakingIt2us.indd 18 16/09/2011 13:40 Cut from Solid: Machining 19

Volumes of production Tolerances These vary according to type, but computer Machined materials can deliver numerical control (CNC)-automated milling exceptionally high levels of tolerance: 1 and turning production involves several ± /2500 inch is normal. cutters working on several parts at the Relevant materials same time, which can result in reasonably Machining is generally applied to metals, high volumes of production. This large but plastics, glass, wood, and even collection of techniques also includes hand ceramics also make use of the machining machining of individual components. process. In the case of ceramics, there are Unit price vs. capital investment certain glass ceramics that are specifically In general, there are no tooling costs designed to be machined and allow for involved, but the mounting and unmounting new forms of processing ceramics. Macor is of work from the machine reduces production a particularly well-known brand. Mycalex, rates. However, the process can still be a glass-bonded mica by the US-based economical for short runs. CNC-automated company Mykroy, is another machinable milling and turning use CAD files to ceramic that eliminates the need for firing. automate the process and produce complex Typical products shapes, which can be batched or mass- Unique parts for industry—pistons, screws, produced. Although standard cutters can turbines, and a mass of other small and large be used for most jobs, specific cutters may parts for different industries. Alloy car wheels need to be produced, which would drive are often put on a lathe to finish the surface. up overall costs. Similar methods Speed The term “machining” encompasses such Varies depending on the specific process. a wide set of processes that it is a family Surface of methods in itself, but you could consider Machining involves polishing, to a degree, dynamic lathing (p.20) as an alternative and it is possible to achieve excellent results to conventional lathing. without the need for post forming. Cutters Sustainability issues can also produce engineered, ultraflat These processes are based only on surfaces. mechanical energy and no heat so energy Types/complexity of shape consumption is low. However, because the Work produced on a lathe dictates that parts nature of these processes is the removal are axisymmetric, since the work piece is of material, a lot of waste is created. rotated around a fixed center. Milled parts Depending on the material, waste can start life as a block of metal and allow for much be reused or recycled. more complex components to be formed. Further information Scale www.pma.org Machined components range in size from www.nims-skills.org watch components up to large-scale www.khake.com/page88.html turbines.

LK016_P0016EDmakingIt2us.indd 19 16/09/2011 13:40 20 Cut from Solid: Machining

Threading is a process that uses a with a special reaming tool that has sharp, serrated tool to create screw several cutting edges. threads in a predrilled hole. Other machining processes Drilling and reaming are include milling and broaching. Milling generally also lathe operations involves a rotating cutter, similar to a (though they can also be done on , which is often used to cut into a a milling machine, or by hand), but metal surface (though it can be applied they require different cutters. As with to just about any other solid material). all lathe operations, the work piece Broaching is a process used to create is clamped in the center of a rotating holes, slots, and other complex . Whereas drilling is a straight- internal features (such as the internal forward operation to create a hole, shape of a spanner head, after it has reaming involves enlarging an existing been forged, see p.187). hole to a smooth finish, which is done

1 A very simple setup for milling a chunk of 2 A straightforward setup for a lathe metal. The cutting tool, which resembles a flat operation in which the tube of metal to be cut , can be seen fitted above the clamped is clamped into a chuck. The cutter is poised work piece. ready to make a cut.

– Very versatile in terms of producing – Can be slow. different shapes. – Parts can be – Can be applied to virtually any solid restricted to the stock material. sizes of material used. – High degree of accuracy. – Low material utilization due to wastage when cutting.

LK016_P0016EDmakingIt2us.indd 20 16/09/2011 13:40 Cut from Solid: Computer Numerical Control (CNC) Cutting 21 Computer Numerical Control (CNC) Cutting

Product Cinderella table Designer Jeroen Verhoeven Materials Finnish birch plywood Manufacturer Demakersvan Country Holland Date 2004 The way computer numerical control (CNC) machines effortlessly cut The surreal construction and shape of this table through solid materials as if they from the “Cinderella” range fits perfectly with the manufacturer’s belief that high-tech machines are were butter is almost sublime. The our hidden Cinderellas. The table is a witty play cutting heads are mounted onto a on traditional, romantic furniture made using head that rotates in up to six axes, to a thoroughly modern manufacturing process. different forms as if they were automated robotic sculptors. Designed by Jeroen Verhoeven, a member of the Dutch design group Demakersvan, the piece of furniture featured here is as multilayered in meaning as it is in its construction.

LK016_P0016EDmakingIt2us.indd 21 16/09/2011 13:40 22 Cut from Solid: Computer Numerical Control (CNC) Cutting

As Demakersvan puts it, “The big table exemplifies perfectly the ability miracle of how industrial products of multi-axis CNC machines to carve come about is a wonderful phenomenon away at three-dimensional forms in if you look at it closely. The high-tech a highly intricate manner, using machines are our hidden Cinderellas. information from a CAD . It is also We make them work in robot lines, a unique example of a totally new while they can be so much more.” form: Created from an ancient material This thought is put into practice in a process that can cut virtually in the production of its Cinderella any shape from a piece of material, this table (pictured). The table is made up table goes some way to reveal what of 57 layers of birch multiplex, which Demakersvan describes as are individually cut, glued, and then the “secrets hidden in high-tech cut again with a CNC machine. The production techniques.”

1 The individual sheets of cut plywood are 2 View showing the machined internal clamped together before being machined. structure before the external surface is cut.

– Can be used on virtually any – Not suited to high- material. volume production. – Designs can be cut straight from – Can be slow. CAD files. – Highly adaptable for cutting intricate and complex shapes.

LK016_P0016EDmakingIt2us.indd 22 16/09/2011 13:40 Cut from Solid: Computer Numerical Control (CNC) Cutting 23

Volumes of production Typical products CNC cutting is best suited to one-off or Ideally suited for making complex custom- batch production because of the slow made designs such as injection-molding progress rate. tools, die cutters, furniture components, Unit price vs. capital investment and the highly crafted, complex forms No tooling, just the expensive time for cutting of handrails. It can also be used, in and the creation, using CAD, of the three- automotive design studios, for rapid dimensional data. prototyping of full-size cars in foam or Speed modeling clay. The speed is determined by several factors, Similar methods including the material, the complexity of the Laser cutting (p.46) when the laser is form, and the surface finish that is required. mounted on a multi-axis head is possibly Surface the closest method. Good, but may require some post finishing, Sustainability issues depending on the material. As the machines have excellent accuracy Types/complexity of shape the amount of wastage produced as a Virtually any shape that can be conceived result of faulty parts or errors is minimal. on a computer screen. Additionally, the layout of parts to be cut Scale can be designed effectively so that there From small components to huge objects. is minimal excess material. Depending CNC Auto Motion in the US, for example, on the material, waste can be reused or is one of several companies manufacturing recycled. monster-sized machines having more than Further information 50 feet of travel, with 10 feet of vertical- www.demakersvan.com axis travel and a gantry measuring www.haldeneuk.com 20 feet across. www.cncmotion.com Tolerances www.tarus.com High. Relevant materials CNC technology can be used for cutting a wide range of materials, including wood, metal, plastic, granite, and marble. It can also be used for cutting foam and modeling clay (see typical products).

LK016_P0016EDmakingIt2us.indd 23 16/09/2011 13:40 24 Cut from Solid: Electron-Beam Machining (EBM) Electron-Beam Machining (EBM)

Product customized tri-flange Electron-Beam Machining (EBM) is implants Materials titanium a versatile process that is used to cut, Country Sweden weld, drill, or anneal components. Date 2005 As a machining process, one of its This titanium hip-bone plate illustrates the many advantages is that ultrafine cuts spattered surface that is a common result can be made with such high precision of this process.

– Highly accurate. – A disadvantage compared with laser – There is no contact with the cutting (see p.46) material being cut, so it therefore is that it requires a requires minimal clamping. vacuum chamber. – Can be used for small batches. – Laser cutting can – Versatile: a single tool can cut, be just as effective weld, and/or anneal at the for less accurate same time. machining. – High energy consumption.

LK016_P0016EDmakingIt2us.indd 24 16/09/2011 13:40 Cut from Solid: Electron-Beam Machining (EBM) 25

that they can be measured in microns. the component, causing the material EBM involves a high-energy beam to heat up, melt, and vaporize. The of electrons being focused by a lens process needs to occur in a vacuum and fired at extremely high speeds chamber to ensure that the electrons (between 50 and 80 percent of the are not disrupted and thrown off speed of light) onto a specific area of course by air molecules.

Volumes of production Tolerances Suited to one-off or batch production. Extremely high, with cuts as fine as Unit price vs. capital investment 10 microns possible. With materials more 1 Low capital investment as there are no than /200 inch thick, the cut will have a fine, tooling costs because the pattern is driven 2-degree taper. by a CAD file. However, the electron-beam Relevant materials equipment itself is very expensive. Virtually any material, although materials Speed that have high melting temperatures slow The beam of electrons moves at a very down the process. high velocity, so cutting speeds are fast. Typical products For example, a hole of up to 125 microns in Apart from engineering applications and diameter can be cut almost instantly in a the medical implant shown here, one 1 sheet /20 inch thick. Naturally, the type of of the more interesting uses for EBM is material and its thickness affects the cycle for joining carbon nanotubes. Joining time. In order to make a 4-inch-wide slot anything on the nano-scale is difficult, 1 in a piece of /150 inch thick, but because there is no contact with cutting will occur at a rate of 2 inches per the material, EBM provides a method of minute. The implant (shown opposite) took joining the tubes together in a way that four hours to produce. does not crush them. Surface Similar methods The process can cause various surface Laser cutting (p.46) and plasma-arc markings that, depending on the cutting (p.33). application, might not be desirable, Sustainability issues such as spattering close to the cut. Very high amounts of energy are consumed Types/complexity of shape to power the beam at such intensity The process is ideally suited to cutting fine and speeds. However, the versatility of lines of holes in thin materials. The beam electron-beam machining ensures that can be focused to 10 to 200 microns, this energy is used effectively, as several which means that costs are justified by processes can be carried out in one cycle. an extremely high degree of accuracy. Additionally, as there is no contact with Scale the material being cut, there is minimal The disadvantage of using a vacuum damage or wear to the machine, which chamber is that part sizes are limited. decreases material consumption through maintenance. Further information www.arcam.com www.sodick.de

LK016_P0016EDmakingIt2us.indd 25 16/09/2011 13:40 26 Cut from Solid: Turning Turning with dynamic lathing

The process of mounting a material on a spinning wheel and skimming off thin slices is thousands of years old. The commonly used material for turning is wood, but “green” ceramic is also highly popular for industrially producing the same types of round, symmetrical shape. In ceramic turning, a clay is blended into a ceramic body and extruded into something called a “pug.” This leather-hard, clay lump is mounted onto a lathe and turned, either by hand or with an automated cutter. At the other end of the industrial production scale, engineers at Germany’s Fraunhofer Institute have developed a process called dynamic lathing for producing nonaxisymmetric metal parts for engineering applications, without the need to remove and replace the component manually. Shapes are defined by a CAD program and fed directly to a lathe that allows the cutter to move up and down in the lateral axis.

Product pestle Materials ceramic , with wooden handle Manufacturer Wade Ceramics Country UK

The turning process has been used for both parts of this pestle, the wooden handle and the ceramic grinder head.

LK016_P0016EDmakingIt2us.indd 26 16/09/2011 13:40 Cut from Solid: Turning 27

Volumes of production Scale From single pieces upward. The costs of A standard maximum size, as produced tooling and setup for a single piece can by Wade Ceramics in the UK, for example, be prohibitive, but this depends on specific is 13¾ inches in diameter by 23½ inches in requirements. For large quantities, an length. A maximum length of 13¾ inches automated process may be required. The with a maximum working diameter of dynamic lathe is currently still in its infancy 13¾ inches is possible with the dynamic- and is best suited to small production runs lathe method. or one-offs. Tolerances 1 Unit price vs. capital investment Tolerance ±2 percent or /125 inch, Depends on volume, but low in comparison whichever is the greater. However, this to other ceramic production methods, such is higher when cutting metal on a lathe, as hot or cold isostatic pressing (see pp.170 especially if using CNC (computer and 172) and slip casting (see p.140). In the numerical control). For dynamic lathe 1 dynamic-lathe method there is no tooling, the tolerance is ± /25 inch. which obviously keeps costs down. Relevant materials Speed Ceramics and wood are common materials Depends on the product. As an example, for turning, however just about any solid a simple candlestick will take 45 seconds, material can be cut in this way. Most a mortar 1 minute, and a pestle 50 seconds. metals and plastics can be used for the The relationship between the length and dynamic-lathe process, although hard depth of the cut in the dynamic-lathe carbon can be problematic. technique determines the speed at which Typical products parts can be made. The more peaks with Bowls, plates, door handles, pestles, larger depths there are, the slower the ceramic electrical insulators, furniture. process is. Similar methods Surface For ceramics, a similar type of rotating Fine surface, but dependent on the material setup is used in both jiggering and (for example, the wooden handle is less jollying (p.29). fine than the ceramic head of the pestle Sustainablity issues shown here). The process is based on the removal of Types/complexity of shape material to leave a three-dimensional form Restricted to symmetrical shapes. Dynamic and therefore results in high quantities are a marked improvement on of wasted material. Depending on the conventional turning on a metalwork lathe, material this may or may not be recyclable. and can produce far more complex parts Further information than might traditionally have been made www.wade.co.uk by casting. www.fraunhofer.de/fhg/EN/press/pi/ 2005/09/Mediendienst92005 Thema3.jsp?print=true

LK016_P0016EDmakingIt2us.indd 27 16/09/2011 13:40 28 Cut from Solid: Turning

1 The mortar bowl is being turned by hand, using a profiled 2 A ceramic pestle being finished using a flat metal tool to achieve a precise profile. smoothing tool.

– Low- or high-volume production – In standard turning, runs. parts are limited to circular profiles. – Can be used for a range of materials. – In the dynamic- lathe process, the – Can have low tooling costs. surface finish is – Dynamic-lathe process allows non- compromised by round shapes to be cut in a single the depth of cut lathe operation. and the number of peaks, both of which also contribute to a reduction in speed.

LK016_P0016EDmakingIt2us.indd 28 16/09/2011 13:40 Cut from Solid: Jiggering and Jollying 29 Jiggering and Jollying

Jiggering and jollying are two to hand throwing comes in. On the profoundly silly words that describe rotating spindle, the clay is drawn up similar methods for the mass- the inside of the mold, forming the production of ceramic hollow shapes, wall. A profiled head is then brought such as bowls, or flatter shapes, such down into the cup to scrape away the as plates. The easiest way to get a clay and form the finished and precise sense of these methods is to think of inside profile. hand throwing on a potter’s wheel, Jiggering is a very similar process but turned into an industrial process to jollying but is used to form shallow where the craftsman’s hands are rather than deep shapes. It works in replaced by a profiled cutter, which an inside-out way to jollying, because scrapes the clay as it rotates on the shaped profile cuts the outside the wheel. In jiggering, the mold surface rather than the inside. Again, a determines the internal form of the slug of clay is formed and placed over a shape while the cutter forms the outer rotating mold, known as a “spreader.” shape, while in jollying the cutter forms the inner shape.

Jollying is employed to make Product Wedgwood® plate deep shapes, the first stage of which Materials bone china involves extruding a clay slug that is Manufacturer Wedgwood® Country UK cut into disks and used to form liners. Date 1920 These are like clay cups that are formed to be of similar proportions to This classic design from the Wedgwood® stable is produced using jiggering, a process that has altered the final piece. The liners are placed little since the foundation of Josiah Wedgwood’s inside the cup molds, which are fitted in 1759, except for the introduction of to a rotating spindle on the jollying electricity to power the wheel. Turn any such plate upside down and you see the shape of the cutting wheel. This is where the similarity profile used to scrape away the clay.

LK016_P0016EDmakingIt2us.indd 29 16/09/2011 13:40 30 Cut from Solid: Jiggering and Jollying

Here, it is formed into an even thickness plate. The whole thing rotates and a by a flat profile. This thick pancake, profile is brought down to scrape away which is known as a “bat,” is removed the external side of the clay and form and placed onto the plate mold. The a precise, uniform outside shape. mold forms the inside shape of the

Volumes of production Typical products Can be used for both batched and mass- Both methods are principally used for production. Many of the big producing tableware and are distinguished use these methods as a standard way of by the depth of the shapes they produce. producing bowls and plates. Jollying is used to make products such as Unit price vs. capital investment pots, cups, and bowls, which are generally Affordable tooling for batch production. deep containers, while jiggering is used The process can also be used for small runs to make shallow items such as plates, of handmade production. saucers, and shallow bowls. Speed Similar methods Jollying produces an average of eight Apart from using a potter’s wheel, the pieces per minute, jiggering an average closest ceramic alternative to jiggering of four units per minute. and jollying is turning (p.26), which can Surface be used to make symmetrical shapes The surface finish is such that the products and different profiles without a large can be glazed and fired without any investment in tooling (although it requires intermediate finishing. a more complex setup). Alternative Types/complexity of shape methods also include cold and hot isostatic Compared with slip casting (see p.140), pressing (pp.170 and 172) and pressure- where the detail on the inside wall of a assisted slip casting (p.140). piece is totally dependent on the outside Sustainability issues form, these two processes allow total The excess clay that is removed from control over both the inside and outside the mold can be reused, which reduces profiles individually. overall material consumption. Firing the Scale clay at high temperatures is very energy The standard size for machine-made intensive, while the initial forming is not. dinner plates is up to a fired diameter of However, several hundred pieces can be approximately 12 inches. fired in a single kiln to make the most Tolerances efficient use of energy. 1 ± /12 inches. Further information Relevant materials www.wades.co.uk All types of ceramic. www.royaldoulton.com www.wedgwood.co.uk

LK016_P0016EDmakingIt2us.indd 30 16/09/2011 13:40 Cut from Solid: Jiggering and Jollying 31

1 A slug of clay is placed on 2 A flat profile forms it into an 3 The bat is transferred by hand a spreader. even “bat.” from the spreader.

4 Manual placement of the bat 5 The profiled head, closely 6 Typical of the sort of flat shape onto the mold. supervised, acts against the produced by jiggering, these soup rotating bat to scrape away bowls are now ready for firing. the clay.

LK016_P0016EDmakingIt2us.indd 31 16/09/2011 13:40 32 Cut from Solid: Jiggering and Jollying

1 A rough disk (liner) is pressed 2 A profiled head spreads the liner 3 Hand finishing of the outer into a deep mold. evenly around the inside of the surface, the side that was in contact rotating mold. with the mold.

– Allows complete control of the – Can be inaccurate thicknesses and shapes of sections. due to shrinkage during firing. – Can be more cost-effective than slip casting (see p.140). – Because these processes both work – Less prone to distortion than on the potter’s wheel cast pots. principle, they are only able to produce symmetrical parts.

LK016_P0016EDmakingIt2us.indd 32 16/09/2011 13:40 Cut from Solid: Plasma-Arc Cutting 33 Plasma-Arc Cutting

“Men in coveralls wearing dark view-control helmets” is perhaps all I need to say to sum up this process. Along with oxyacetylene cutting (see p.48), plasma-arc cutting lives in the land of heavy industry, and it is part of the non-chip-forming branch of production known as thermal cutting. It works by means of a stream of ionized gas, which becomes so hot that it will literally vaporize the metal that is being cut. The process takes its name from the term “plasma,” which is what a gas turns into when it is heated to a very high level. It involves a stream of gas—usually nitrogen, argon, or oxygen—being sent through a small channel at the center of a nozzle, which at its heart contains a negatively charged . The combination of power supplied to this electrode, and contact between the tip of the nozzle and the metal being cut, results in a circuit being created. This produces a powerful spark, the arc, between the electrode and the metal work piece, which heats the gas to its plasma state. The arc can reach temperatures as high as 50,000°F and it therefore melts the metal as

This shows the heavy, industrial nature of this particular cutting method. The tube is rotated around the central axis to allow for a short length to be removed.

LK016_P0016EDmakingIt2us.indd 33 16/09/2011 13:40 34 Cut from Solid: Plasma-Arc Cutting

1 1 the nozzle passes over it. The its thickness can range from /25 to /6 cutting line width, known as the inches, depending on the thickness “kerf,” needs to be considered when of the metal plate, and can affect the designing certain shapes because dimensions of the component.

Plasma-Arc Cutting negatively charged electrode

water

cutting gas

ionized gas positively charged metal work piece

A stream of pressurized, superhot ionized gas flows through a tiny water-cooled nozzle at high speed, forming an arc of plasma between the electrode and the positively charged metal part that is being cut. The work piece is thus melted and oxidized by an exothermic reaction.

– Can be either a manual or an – Not suitable for automated process. sheets less than 1 /12 inch thick. – Suited to thick sheets. – Can be used on a larger range of metals than is possible with oxyacetylene cutting.

LK016_P0016EDmakingIt2us.indd 34 16/09/2011 13:40 Cut from Solid: Plasma-Arc Cutting 35

Volumes of production Scale Plasma-arc cutting is an economical Handheld cutting means there is no process for small-batch quantities because maximum size. Sheets thinner than about 3 it can be performed without tooling. /8 inch may distort. Unit price vs. capital investment Tolerances Unless a cutting template is introduced, Depend on the thickness of the material, the process does not require tooling. but, to give a basic idea, it is possible 1 In the automated process, the information to keep tolerance to ± /17 inch for sheet 3 for the shape is provided by CAD files. materials ¼–1 /8 inch thick. Speed Relevant materials There is generally very little setup time Any electrically conductive metallic involved, but the speed is greatly affected material, but most commonly stainless by the type of material and its thickness. steel and aluminum. The process becomes For example, to cut a 1-inch chunk more difficult the higher the carbon of steel, 12 inches long, will take about content of the steel. 1 1 minute, whereas a /12 -inch piece can be Typical products cut at a rate of 94 inches per minute. Heavy construction, including Surface shipbuilding and machine components. Even when hard stainless steel is used, Similar methods the process provides smooth, clean edges Electron-beam machining (EBM) (p.24), with better results than those produced by oxyacetylene cutting (p.48), and laser oxyacetylene cutting (see p.48). The cutting (p.46) and water-jet cutting (p.42). can also be controlled to produce different Sustainability issues grades of surface, depending on the cost One of the most energy-intensive versus the edge quality—that is, longer processes around, plasma-arc cutting cutting times equal better edge finish. requires extreme heat and pressure for the Types/complexity of shape gas to achieve cutting strength. Because The process is best suited to heavy- shapes can sometimes be cut from sheets materials. Thin-gauge metals of below there is also a high amount of material 3 /8 inch may distort as a result of the wastage. process, as may thin and narrow sections. Further information As in all sheet-cutting operations, nesting www.aws.org one shape within another (as when you www.twi.org.uk/j32k/index.xtp make cookies and cut them as close as www.iiw-iis.org possible to make the most of the rolled www.hypertherm.com dough) results in an economical use of www.centricut.com the material.

LK016_P0016EDmakingIt2us.indd 35 16/09/2011 13:40 2: Sheet

38 Chemical Milling 40 Die Cutting 42 Water-Jet Cutting 44 Wire EDM (Electrical Discharge Machining) and Cutting 46 Laser Cutting 48 Oxyacetylene Cutting 50 Sheet-Metal Forming 52 Slumping Glass 54 Electromagnetic Steel Forming 56 Metal Spinning 59 Metal Cutting 61 Industrial Origami® 64 Thermoforming 67 Explosive Forming 70 Superforming Aluminum 73 Free Internal Pressure-Formed Steel 76 Inflating Metal 78 Pulp Paper 80 Bending Plywood 83 Deep Three-Dimensional Forming in Plywood 86 Pressing Plywood

LK016_P0036EDmakingIt2us.indd 36 16/09/2011 14:06 Components that start life as a sheet of material

Within the last fifteen years or so, there has been a surge in the number of products made from sheet material. Maybe this is because the starting point is a preprepared material, which goes some way in reducing the production costs. Maybe it is also the cost-effectiveness of die-cutting tools, or even the absence of any tooling costs for processes such as chemical milling. But, on a mass-market level, the die cutting of a plastic such as has led to a wealth of new packaging, lighting, and even larger-scale furniture. Perhaps it is also the ability of these materials to be cut by a manufacturer and handfolded and assembled by the consumer that has created an appeal.

LK016_P0036EDmakingIt2us.indd 37 16/09/2011 14:06 38 Sheet: Chemical Milling Chemical Milling AKA Photoetching

Product Mikroman business card Chemical milling, also known as Designer Sam Buxton Materials stainless steel photoetching, is a great method for Date 2003 producing intricate patterns on thin, flat metal sheets by using corrosive The fine, intricate details of these cleverly designed business cards, which unfold to show a man on a acids in a process similar to that used bicycle and one in an office environment, are an for developing photographs. excellent example of the ability of chemical milling Chemical milling involves a resist to offer a highly decorative and ultrafine method of cutting metals. being printed onto the surface of the material to be treated. This resist works by providing a protective layer against the corrosive action of the acid, and it can be applied in the form of a linear pattern or a photographic image. When

– No tooling. – Can only be used for metals. – Highly flexible process for creating surface detail. – The image is laser-plotted onto film from a CAD file, so designs can easily be modified. – Fine tolerances. – Suitable for thin sheets.

LK016_P0036EDmakingIt2us.indd 38 16/09/2011 14:06 Sheet: Chemical Milling 39

the part is sprayed with an acid on can be “half-etched” into the pattern, both sides, the exposed metal (without which allow the sheet to have foldable the resist) is eaten away by the crease lines for the creation of three- chemical. As in the die-cutting process dimensional structures. (see p.40) used for plastics, crease lines

Volumes of production Typical products Individual pieces can be made, but the Electronic components such as process is more suited to batch or mass- contacts, actuators, microscreens, and production volumes. graphics for industrial labeling and signs. Unit price vs. capital investment The process is also used for industrial The setup costs involved are low, because components, and the military use it to the printed resist removes the need for any make a flexible trigger device for missiles. hard tooling. However, the unit costs are The trigger is so fine that it changes not likely to be drastically lower for batch according to air pressure the closer it items than for mass-produced items. gets to its target. Speed Similar methods Depends on the complexity of the artwork. Electron-beam machining (p.24), laser Surface cutting (p.46), blanking (see metal Due to the corrosion of the metal, any cutting, p.59), and electroforming for half-etched surface has a rough and micro-molds (p.250). matte texture. However, this texture often Sustainability issues becomes a decorative feature. Cut edges Although the process involves the use of are free of burring. harmful chemicals, responsible disposal Types/complexity of shape has been introduced through a cleaning The process is ideal for cutting thin sheets process that removes contaminants and and foils. It also allows for highly intricate allows the liquids to be recycled back into shapes and details to be cut without any the process. This reduces waste along blemishes such as the burn marks that with water consumption. Additionally, are sometimes caused by laser cutting the complexity and accuracy of the (see p.46). etching means no secondary processing Scale is necessary, saving further resources and Generally limited to standard sheet sizes. energy. Unlike with mechanical cutting Tolerances methods, waste material is not available Tolerance levels are determined by the to recycle. thickness of the material. The holes must Further information be larger (typically 1 to 2 times) than the www.rimexmetals.com thickness of the metal, which gives a www.tech-etch.com material with a thickness of between www.precisionmicro.com 1 1 1 /1000 and /500 inch a tolerance of ± /1000 inch. www.photofab.co.uk Relevant materials A range of metals can be used in the process, including titanium, tungsten, and steels.

LK016_P0036EDmakingIt2us.indd 39 16/09/2011 14:06 40 Sheet: Die Cutting Die Cutting

The simplest analogy for this process is to think of a cookie cutter for making shapes from dough in the kitchen. Just as easily applied to paper or plastic, die cutting is a simple process that involves a sharp edge being brought down onto a thin material to cut a shape in a single step. A die-cutting tool has two functions: The main function is to cut a shape from the sheet; the second is to apply creases to the material to allow it to form an accurate bend. The creases are necessary when constructing three- dimensional shapes and integrated hinges from a sheet.

Product Norm 69 lampshade Designer Simon Karkov Materials polypropylene Manufacturer Normann Copenhagen Country Denmark Date 2002

The 69 lampshade (above) is sold, flat, in boxes of pizza-size proportions. The flat pieces of die- cut plastic that are contained in the box take the customer about 40 minutes to fold and assemble into this complex structure.

– Low setup costs and cost-effective – Three-dimensional for batches. products need hand assembly – Can easily be combined with and are limited to printing. a set of standard – Many shapes can be cut in a single constructions. cutting action.

LK016_P0036EDmakingIt2us.indd 40 16/09/2011 14:06 Sheet: Die Cutting 41

Volumes of production Tolerances From small batches of around a hundred Very high tolerances. units, to thousands. Relevant materials Unit price vs. capital investment A large proportion of the material used The low cost of the cutters makes this is polypropylene due to its ability to form a highly economical process even for a strong integral hinge. Other standard small runs. Sheets of material may be fed materials include PVC, individually but if the material comes on terephthalate (PET), paper, and all sorts a roll there will be a massive reduction of cardstock. in the cost of the final products. Typical products Speed Die cutting is extensively used for Die cutting is one of the predominant packaging, especially boxes and cartons. manufacturing processes for packaging, For this type of product, assembly is with production cycle times of up to required to construct the three-dimensional thousands of products per hour. Unlike in structures. Other, more product-focused, molded products, the cutting speed is not applications include lampshades that affected by the complexity of the shape. require complex assembly (pictured), Assembly, however, is more labor-intensive. toys, and even furniture. Surface Similar methods The surface is dependent on the material. For cutting flat sheets, try laser (p.46) The cut edge, however, is clean, precise, or water-jet cutting (p.42). and with a very, very fine radius where Sustainability issues the cutter has cut through the material. Die cutting can be more economical in As you might expect, the sheets can be terms of material use if shapes are nested finished with various forms of printing or and material wastage is reduced. The embossing, or a combination of the two. nature of the material determines Types/complexity of shape whether waste (of which there will be The complexity of the shape is really a considerable amount) can be reheated dependent on the size of the cuts. Very and recycled. 1 fine slots of less than about /5 inch can be Further information difficult to cut. One of the design issues to www.burallplastec.com bear in mind is that the excess plastic around www.ambroplastics.com the part needs to be removed and cleaning www.bpf.co.uk plastic from fine holes can be difficult. Scale Most manufacturers should have no problems at all in cutting sheets of up to 1,000 by 28 inches, and some are able to go slightly larger and cut straight from a roll. However, material choice is more limited if it comes on a roll. Printing on large sheets, above 1,000 by 28 inches, may be difficult due to the limited availability of large-scale printing machines.

LK016_P0036EDmakingIt2us.indd 41 16/09/2011 14:06 42 Sheet: Water-Jet Cutting Water-Jet Cutting AKA Hydrodynamic Machining

From as early as the mid-nineteenth a nozzle at a pressure of 20,000–55,000 century, water jets have been used psi (pounds per inch) as a method of removing materials at velocities of up to twice the speed during mining. The modern-day of sound. Water-jet cutting produces process (also known as hydrodynamic a fine cut using water alone, but machining) has been cranked up to with an additional , such as produce an incredibly fine jet of water, garnet, it can be used to cut through 1 typically /50 inch, which is forced out of harder materials.

Product Prince chair Designer Louise Campbell Materials water-cut EPDM (ethylene propylene diene ) on laser-cut metal, and Manufacturer Hay Country Denmark Date 2005

The decorative pattern on this chair illustrates the potential of water-jet cutting to cut intricate patterns into a three-dimensional material.

– A cold process, so it does not heat – In particularly thick the material. cuts, the jet can move from its original – No tool contact, therefore no edge course as it eats into deformation. the depth of the – Can be used to cut very fine material. details in a variety of materials of different thicknesses.

LK016_P0036EDmakingIt2us.indd 42 16/09/2011 14:06 Sheet: Water-Jet Cutting 43

Volumes of production Relevant materials The process involves no tooling and is Water-jet cutting offers a huge range of therefore equally suitable for one-off jobs possibilities in terms of materials—you and large production runs. can choose from glass, steel, wood, plastic, Unit price vs. capital investment ceramics, stone, marble, and even paper. Because there is no tooling, and designs It is also used for cutting sandwiches and are taken from CAD files, setup costs are other food. Having said that, it is worth low, and there is no consequent hike in unit bearing in mind that materials that are price. Shapes can also be “nested”—laid particularly prone to absorbing water are out in a clever way to maximize the surface not suited to this process. area of the sheet (as you would when Typical products cutting out cookies from rolled dough). Decorative architectural panels and Speed stones. The process works very well An abrasive jet can cut a ½-inch-thick under water, and it was used in the rescue titanium sheet at the rate of 6¼ inches operation of the Russian Kursk submarine per minute. in 2000. Surface Similar methods The cut edge has the same sort of edge as if The process can be used as an alternative it had been sand-blasted, but without any to die cutting (p.40), and as a cold of the burring that you may get with laser alternative to laser cutting (p.46). cutting (see p.46). Sustainability issues Types/complexity of shape The water used for cutting can be recycled Because the cutter works like a plotting back into the process to form a closed loop machine or a CNC router, it is possible to cycle, which reduces water consumption cut fine and intricate shapes. However, due and resources. Additionally, with no tool to the high pressure of the water, thin sheet contact, maintenance and material use material may distort or bend. Processes through replacement parts is reduced. such as laser cutting avoid this problem No heat is required so energy use is due to the lack of such pressure. fairly low while no fumes, toxins, or Scale contaminants are released during cutting. Most industrial cutting takes place on a The nature of the material determines cutting bed, which restricts the size of the whether waste (of which there will be material that can be used. Standard sizes a considerable amount) can be reheated extend up to a maximum of 10 by 10 feet. and recycled. The upper limit for thickness varies with Further information the material. www.wjta.org Tolerances www.tmcwaterjet.co.uk 1 The jet can be accurate to /250 inch. www.waterjets.org Particularly thick materials may result in www.hay.dk the jet “wandering” slightly from its point of entry.

LK016_P0036EDmakingIt2us.indd 43 16/09/2011 14:06 44 Sheet: Wire EDM (Electrical Discharge Machining) and Cutting Wire EDM (Electrical Discharge Machining) and Cutting with Ram EDM

Designers are rediscovering the extremely hard steels and other hard- use of surface decoration as a valid to-cut metals such as high-performance form of design expression. Industrial alloys, carbides, and titanium, it is, techniques have been borrowed from nevertheless, able to achieve the same engineering applications and are level of intricacy. used to create highly intricate Based on a type of spark-erosion patterns, as decorative as if they (it is sometimes also referred to as spark have been abstracted from nature machining or spark eroding), wire EDM or fairy-tale narratives. is used to cut very hard, conductive Many unusual methods have been metals by using sparks to melt away invented for cutting complex patterns the material. The spark is generated into difficult materials. Dating back by a thin wire—the electrode—which to when the phenomenon was first follows a programmed cutting path observed in the 1770s, electricity has (determined by a CAD file). There is no been harnessed by scientists for use in contact between the electrode and the cutting and machining materials. Wire material, so the spark jumps across the EDM (electrical discharge machining) gap and melts the material. Deionized is one of the latest processes to exploit water is simultaneously jetted toward electricity for cutting intricate patterns. the melting point, cooling the material Since its commercial development and washing the waste away. in the 1970s, wire EDM has become There is another sort of EDM an increasingly popular method of machine, the “ram.” As the name machining metals. Together with suggests, the ram method involves a processes such as water-jet cutting machined graphite electrode mounted (see p.42) and laser cutting (see p.46), on the end of an arm (the ram) being Wire EDM is a noncontact method of pushed onto the surface of the material cutting materials. Less commonly used to be cut. than the other two and more suited to

LK016_P0036EDmakingIt2us.indd 44 16/09/2011 14:06 Sheet: Wire EDM (Electrical Discharge Machining) and Cutting 45

Volumes of production Tolerances The process and shape can be controlled Wire EDM is extremely accurate and manually by an operator or from a CAD file, can achieve submicron tolerances. so it is equally suited to one-off pieces Relevant materials and automated mass-production. Restricted to conductive metals. The Unit price vs. capital investment process is ideally suited to hard metals, Requires no tooling. the hardness of which does not affect Speed the cutting speed. The latest generation of EDM machines can Typical products cut more than ½ square inch per minute, One of the big markets for this process is depending on the electrical resistance of for the super-hardened dies and cutters the material and, of course, its thickness. A that are used in industrial production. 2-inch piece of steel can be cut at a rate of Other applications include supertough 1 approximately /6 inch per minute. components for the aerospace industry. Surface Similar methods Wire EDM is well known for its ability Laser cutting (p.46) and electron-beam to achieve an excellent finish. machining (EBM) (p.24). Types/complexity of shape Sustainability issues The delicate wire can cut very intricate Power consumption is very high, especially shapes from the toughest materials. as the cutting rate is slow, which results Scale in long cycle times. Leftover materials Depending on the material, the generator need to be melted down and recycled size, and the power, the process can cut back into the process to reduce material through massive hunks of metal up to an consumption and waste. astonishing 20 inches thick, although this Further information will be very time-consuming, with cutting www.precision2000.co.uk 1 occurring at a rate of less than /25 inch www.sodick.com per minute. www.edmmachining.com

– Ideal for cutting intricate shapes – Time-consuming. from metals that would be difficult to machine. – Limited to electrically conductive materials. – The process cuts without force. – No flushing.

LK016_P0036EDmakingIt2us.indd 45 16/09/2011 14:06 46 Sheet: Laser Cutting Laser Cutting with laser-beam machining

Similar to water-jet cutting (see Laser-beam machining is a form p.42) and electron-beam machining of laser cutting that uses a multi-axis (see p.24), laser cutting is a non- head to cut three-dimensional objects. chip-forming method of cutting and A CAD file maps complex paths for the decorating materials. It is a highly powerful beam of light, resulting in accurate process based on input from fine, accurate designs. a CAD file. In a nutshell, it works Both processes can cut through a highly focused beam of light components that could not be cut generating millions of watts of energy precisely with conventional machine per square inch, which melts the tools. As neither method involves material that is in its path. contact with the material being cut, minimal clamping is required.

Product Spiral Designer Torafu Architects Materials paper Manufacturer Kamino Kousakujo Country Japan Date 2010

This is a paper bowl that envelops air. You can freely change its shape by molding it. The thin and lightweight paper gains tension and strength when pulled out. The soft, white color and delicate expressions of this airvase allow it to subtly blend into any scene.

– No tool wear, minimal clamping, – Has an optimum and it offers a consistent, highly thickness from which accurate cut. materials can be cut, beyond which you might – Suited to a range of materials. run into problems. – No post treatment of edges. – Can be time-consuming on large production runs, so it is best suited to one-off or batch production.

LK016_P0036EDmakingIt2us.indd 46 16/09/2011 14:06 Sheet: Laser Cutting 47

Volumes of production Relevant materials Suited to batch production. Often used on hard steels such as stainless Unit price vs. capital investment and carbon steel. Copper, aluminum, gold, Low capital investment as there is no and silver are more difficult due to their tooling because the cuts are determined ability to conduct the heat. Nonmetallics by a CAD file. can also be laser cut, including woods, Speed paper, plastics, and ceramics. Materials As with all methods of cutting, the speed such as glass and ceramics are especially of this process is dependent on the type of suited to laser cutting, since it would be material used and its thickness. As a rough difficult to cut the materials in intricate 1 3 estimate, titanium alloys between /50 and /8 patterns using any other techniques. inch thick can be cut at a rate of 8 to 40 feet Typical products per minute. Model components, surgical instruments, Surface wooden toys, metal meshes and filters. The process will leave burn marks on wood, Laser-cut ceramics can be used as but on metal can give a clean edge with industrial insulators and furniture can be no need for post finishing. However, metal produced using laser-cut glass or metal. surfaces should be left unpolished before Similar methods cutting, as highly polished surfaces act as Water-jet cutting (p.42), die cutting (p.40), reflectors and decrease the effectiveness electron-beam machining (EBM) (p.24), of the process. and plasma-arc cutting (p.33). Types/complexity of shape Sustainability issues Depending on the machinery, the laser can Laser cutting is very energy intensive be mounted horizontally or on a multi-axis in order to sustain the beam intensity, head, allowing for highly complex shapes to and the speed is considerably slower be cut in three dimensions, a method that is when working with thick or large pieces. sometimes called laser-beam machining. However, as no contact is made between Scale the tool and the substrate, maintenance Limited to standard sheet sizes. is low and this reduces material Tolerances consumption through replacement parts. Tolerances are extremely high, with As with all sheet cutting techniques, 1 holes of as little as /1000 inch in diameter material wastage is often high. The nature being possible. of the material determines whether waste can be reheated and recycled. Further information www.miwl.org.uk www.ailu.org.uk www.precisionmicro.com

LK016_P0036EDmakingIt2us.indd 47 16/09/2011 14:06 48 Sheet: Oxyacetylene Cutting Oxyacetylene Cutting AKA Oxygen Cutting, Gas , or Gas Cutting

This is a process for cutting metal plate narrow materials are not suited to the in which oxygen and acetylene are process because the heat can cause combined at the end of a nozzle and them to distort. ignited, producing a high-temperature This sort of cutting can be flame. The metal is preheated with this undertaken either manually or as an mixture of gases, and then a stream automated process. In the manual of high-purity oxygen is injected into operation, the familiar worker in the center of the flame, which rapidly coveralls, with full-face protection, oxidizes the work piece. Because provides the traditional image that thermal cutting methods are based sums up this process. In this scenario, on a chemical reaction between the the worker may often be welding, oxygen and (or titanium), thin or rather than cutting, materials.

high-purity Oxygen and acetylene are oxygen and oxygen and oxygen combined at the end of a acetylene acetylene nozzle, and ignited to produce a high-temperature flame.

heating flame conducted heat heavy-gauge metal

jet

– Suited to thick metal plate. – Restricted to a narrow range – Adaptable to hand or of materials. automated use.

LK016_P0036EDmakingIt2us.indd 48 16/09/2011 14:06 Sheet: Oxyacetylene Cutting 49

Volumes of production 90 degrees to the plate. Other angles can Compared with the alternatives for cutting also be achieved, although this is not as thick metals, thermal cutting is an economical easy to set up for oxyacetylene cutting process for small-batch production. as it is for . Unit price vs. capital investment Scale Unless a cutting template is introduced, Using handheld cutting tools there is no the process does not require tooling. In an maximum size, while in the automated automated process, the information for the process part sizes are restricted to the shape can be provided by CAD files. Both of size of the machinery. these factors mean that costs are kept down. Tolerances Speed Depend on the thickness of the material The speed is greatly affected by the type but, as a rule of thumb, they vary between 1 3 of material used and its thickness. The ± /17 inch for ¼–1 /8-inch-thick materials. process may be carried out manually, or it Relevant materials can be highly automated, with multitorch, Limited to ferrous metals and titanium. computer-operated systems. Speeds can Typical products reach up to 10 feet per minute. Heavy construction, including Surface shipbuilding and machine components. Cutting can be controlled to produce Similar methods different grades of surface depending on the Electron-beam machining (EBM) (p.24), cost-versus-edge quality—that is, longer plasma-arc cutting (p.33), laser cutting cutting times equal better edge finish. The (p.46), and water-jet cutting (p.42). finish of the edge is also determined by the Sustainability issues material, but generally plasma-arc cutting Oxyacetylene cutting is extremely energy (see p.33) will give the best finish. intensive because of the phenomenal Types/complexity of shape temperatures required to maintain the The process is best suited to heavy-gauge heat of the flame, along with the slow 3 materials. Metals of below /8 inch may speed at which the torch needs to move, distort as a result of the intense heat, as which increases cycle times. In addition, might narrow sections. As in all sheet- several harmful chemicals are produced cutting operations, nesting one shape from both the fuel and the work piece. within another (as you would when cutting Further information cookies from dough) to optimize space in www.aws.org between shapes produces an economical www.twi.org.uk use of the material. The cut is generally at www.iiw-iis.org

LK016_P0036EDmakingIt2us.indd 49 16/09/2011 14:06 50 Sheet: Sheet-Metal Forming Sheet-Metal Forming

Making objects from is that is based on the conversion of a one of the earliest methods of human sheet material into a three-dimensional production. The Egyptians, for instance, object by cutting, press forming made soft precious metals, such as (see metal cutting, p.59), and, finally, gold, into sheets, from which they cut plating sheets of brass. However, this sometimes highly intricate forms. overly simplified description masks One of the most refined the fact that this is a precise method applications for sheet-metal forming of industrial production that requires can be found in the production of the extremely high levels of tolerance common whistle. Falling under the to produce a whistle with the generic heading of solid-state forming, perfect pitch. the production of whistles is an The basic geometry of a whistle’s industrial craft, a multistage process body consists of three parts: an underside, mouthpiece, and top and side. The pieces of brass are stamped out to form the flat nets and are then pressed into shape using a male and female . These components are soldered together, polished, and plated in nickel. The final simple step: a cork pea is pushed into the mouthpiece. In any wind instrument, the sound is the result of air flowing at different rates over a very sharp edge, producing two vibrating columns of air. After 135 years, Acme Whistles, in Birmingham in the UK, has tailored this highly precise process into an art form, producing a reject rate of just 3 percent for their whistles. Product Acme Thunderer whistle Considering the potential for the Designer Joseph Hudson slightest, sometimes invisible, Materials nickel-coated brass (image shows the brass before plating) imperfection to produce the wrong Manufacturer Acme Whistles sound, this really is a feat of crafted Country UK industrial manufacturing. Date 1884

The Acme Thunderer is shown here in its pre- assembled state, and before it is nickel-plated. This shows how many formed components go into making the final product.

LK016_P0036EDmakingIt2us.indd 50 16/09/2011 14:06 Sheet: Sheet-Metal Forming 51

Volumes of production Relevant materials This is a semiautomated method, so it Soft metals such as brass, copper, and can be used for production runs of greatly aluminum are particularly easy to form, varying lengths. but any sheet metal can be used. Unit price vs. capital investment Typical products This varies greatly, depending on the setup Sheet-metal forming is used to produce and the volume of production required. a number of products in a variety of Jewelers can use simple tools requiring industries—they range from brass musical very little investment. By contrast, millions instruments to computer housings and of pounds would be needed to set up a automobile bodies. production process for the whistle (pictured). Similar methods Speed Other processes that give form to flat Varies according to setup. The Acme sheets of metal include metal spinning Thunderer featured here takes up to three (p.56), and (see metal days to produce. cutting, p.59), water-jet cutting (p.42), Surface laser cutting (p.46), and CNC folding, a Generally, this is dependent on the finish process in which sheet material, usually of the sheet material, though polishing and metal, is folded into different shapes— painting are often required. think of a cookie tin. Types/complexity of shape Sustainability issues The nature of this type of setup allows jigs As this process is largely automated it to be built to accommodate a range of quite consumes a fair amount of energy while complex shapes. the numerous stages of production can Scale increase cycle times. However, excess or There is no maximum size for sheet forming. metal scraps can be recycled back into Tolerances the process; aluminum is one of the most Can be extremely high. In order to achieve recycled materials. perfect pitch in the whistle, tolerances are Further information 1 ± /3000 inch. www.acmewhistles.co.uk

– The beauty of this process is – Limited to sheet that it allows the creation of materials. a complex form with a highly precise component. – The product may have to go through – Reasonable tooling costs. a number of stages.

LK016_P0036EDmakingIt2us.indd 51 16/09/2011 14:06 52 Sheet: Slumping Glass Slumping Glass

To slump glass is to allow it to sink into To form the Fiam table (pictured), shape. Most people know that if a sheet a blank sheet of ½-inch crystal glass of glass is left alone long enough, its is first cut. The computer-controlled shape will slowly distort. However, process employs a jet of water, mixed glass does need to be heated to a with an abrasive powder, that passes sufficiently high temperature for it to at 3,200 feet per second through a reach an elastic state that enables it to tiny nozzle. This creates a jet strong move at an economical rate or, at the enough to cut through any material. very least, faster than the hundreds of Once the flat blanks have been cut, the years it would take without heat. When sheet is ready for curving. a sheet of stiff glass is placed over a The entire sheet and the refractory mold (a mold made from a refractory mold must be brought to the heat-resistant material) in a kiln and same critical melting temperature— heated to 1,165ºF, the glass relaxes even the smallest temperature enough to allow it to sag into a shape variation can result in a broken sheet. that becomes permanent once cooled. At the right temperature, the glass is relaxed enough to sag under its own weight and sink into the mold, with a bit of manual assistance. The apparent simplicity of Fiam’s products conceals the complex heating process, which has to be tightly regulated to keep the glass at exactly the right temperature inside the curving chamber. The pieces may be based on simple ideas and shapes, but this simplicity is only achieved (with a high success rate) by the use of sophisticated modern technology.

Product Toki side table Designer Setsu and Shinobu Ito Materials float glass Manufacturer Fiam Italia Country Italy Date 1995

The full radius of the tabletop curve, and the gentle curves of the feet, offer a suggestion of the simple forms that are possible with glass slumping.

LK016_P0036EDmakingIt2us.indd 52 16/09/2011 14:06 Sheet: Slumping Glass 53

Volumes of production expansion of the glass, it can be difficult Slumping is the kind of process that is to achieve tight tolerances. as well suited to one-offs as it is to Relevant materials batch production. Most types of sheet glass (including Unit price vs. capital investment borosilicate), soda-lime glass, and Most commercially available molds are advanced materials such as fused made of either vitreous clay or stainless quartz and glass ceramic. steel, but it is also possible to use plaster, Typical products cement, or even found objects for low- Domestic products such as bowls, volume production. Depending on the plates, magazine racks, tables, chairs, complexity of the shape, the process can and tableware. Industrial applications involve a high failure rate of finished pieces include automotive windscreens, lighting and, therefore, high unit costs. reflectors, furnaces, fireplace windows. Speed Similar methods Although this is an industrial process, the Draping glass over a mold, rather than speed of forming is quite slow and still into a mold, is also a valid process, and is requires a considerable use of manual labor. sometimes just called “draping.” Surface Sustainability issues Completely smooth glass surfaces can be Working with glass is always extremely achieved, as well as textures that can be energy intensive as high temperatures incorporated into the mold. need to be sustained in order to keep it in Types/complexity of shape a workable state. In addition, the shaping This process works on gravity, so it is is done by hand so faults can often occur. possible to achieve any shape that is Any rejects from errors or breakage can formed from a flat sheet and has a be recycled back into the process through vertical drape. melting, which requires further heating. Scale Further information Restricted only by the dimensions of the www.fiamitalia.it glass sheet and the kiln that provides www.rayotek.com the heat. www.sunglass.it Tolerances Due to the difficulty of making glass slump into tight corners, coupled with the

– Allows sheet glass to be formed into – Slow, and a high a unique three-dimensional shape degree of skill and in as little as a single operation. experience can be required to trial and error a design.

LK016_P0036EDmakingIt2us.indd 53 16/09/2011 14:06 54 Sheet: Electromagnetic Steel Forming Electromagnetic Steel Forming

Electromagnetic pulses in manufacture amount of magnetism by means of a may seem very complex, but this new coil, an electrical current, and a steel use of an existing technology is likely sheet. A (the container to revolutionize the production of large holding the electrical current) steel parts for the automotive industry. discharges the current rapidly through At present, large steel sheets are the coil where it is converted into a cut using a metal stamping process in powerful . The pressure which a heavy mold presses the sheet of this magnetic field hits a steel sheet into a die shape. However, this has a placed near the coil and the opposing number of drawbacks including the forces between the sheet and the enormous size of the machinery and current in the coil is so strong that it the poor quality of the cutting edge, causes the metal to deform. Energy which is very jagged and requires a is directed and concentrated so that secondary finishing process often very precise and refined punches are done by hand. For these reasons made into the steel sheet without any electromagnetic-pulse forming is physical contact. The impact pressure revered as the next big contender in is said to be the equivalent of three steel forming: it offers improvements small cars pressing on an area about in both areas and reduces costs the size of a fingernail. and time. The use of electromagnetic If you try to make two magnets pulses is not new—in the past they touch, you either feel them attract, were used in warfare to disable or you turn them around and you telecommunications. More recently feel a force that physically pushes the technology has been used for them away from each other. This small-scale tube forming. To apply it to manufacturing process simply large sheets of steel, scientists simply amplifies this latter force, using a altered the machines for tube forming much greater and carefully directed by boosting the coil and the rate at

– A very clean and refined is – The process is still achieved, so secondary finishing in development processes are eliminated. so it could be a while before it is – The process could eliminate the commercially viable. need for molds or dies and, in turn, reduce costs significantly. – Energy consumption is likely to be very – The risk of operators being injured high because of is reduced in comparison to the high pressures stamping. required.

LK016_P0036EDmakingIt2us.indd 54 16/09/2011 14:06 Sheet: Electromagnetic Steel Forming 55

which the charge could be converted. Researchers are working on developing coils that will cut specific shapes and geometries.

Volumes of production Relevant materials The process is being developed A range of magnetic metals (that is, predominantly within the automotive the process is not suitable for use with industry for mass-production scales. aluminum, etc.), and significantly tough Unit price vs. capital investment materials such as stainless steel and other High investment costs for start- hardened metals. up production. However, existing Typical products electromagnetic forming machines can be The process is best suited to large panels, altered quite simply with a more powerful such as automobile doors, frames, coil. Overall costs are reduced due to low and hoods. It is also used for home maintenance of parts and the elimination appliances, including washing machines, of secondary finishing processes. dishwashers, and refrigerators, etc. Speed Similar methods The process can cut parts up to seven Superforming aluminum (p.70), press times faster than laser cutting. Speeds forming (p.59), Industrial Origami® (p.61). 1 are incredibly high (a 1 /8 -inch-diameter Sustainability issues hole can be punched in one-fifth of Energy consumption is likely to be very a second). high due to the intensive pressures that Surface are required to deform the steel sheets. The main benefits of the process derive However, electromagnetic forming predominantly from the use of a magnetic requires no tooling or contact with the field in place of a cutting tool (as with steel, which reduces material consumption stamping): there is no wear or damage to through maintenance and replacement of any parts as no physical contact is made parts during the lifespan of the machine. between the materials. As a result, the Further information punched edges are very refined, which http://www.fraunhofer.de/en eliminates the need for additional finishing and in turn reduces cycle time and costs. Tolerances Testing has shown that the process can punch holes in stainless steel and other hardened metals, and could also be used to form shapes in metal without the need for a die or mold. This opens up entirely new opportunities within the manufacture of heavy metals, affirming the process as a valuable tool in the future of automotive and vehicle production.

LK016_P0036EDmakingIt2us.indd 55 16/09/2011 14:06 56 Sheet: Metal Spinning Metal Spinning including sheer and flow forming

Spinning is a widely used technique clamped against the and then for bending sheet metal. As the name both are rotated at high speed, in the suggests, the process involves a flat same direction. The spinning metal metal disk, known as the blank, being is then pushed with a tool—which in spun, pushed, and consequently is sometimes called the wrapped around a rotating mandrel to “spoon”—against a wooden mandrel produce curved, thin-walled shapes. until it fits to the mandrel’s shape. A flat metal sheet (the blank) is first The resulting part is thus a copy of the

Product Spun Designer Thomas Heatherwick Materials brushed/polished steel or copper Manufacturer Haunch of Venison Country UK Date 2010

These large metal spinnings perfectly illustrate the typical forms that are the result of the process, even down to the spinning lines which are clearly visible. Though these works are substantial, even larger forms are possible.

LK016_P0036EDmakingIt2us.indd 56 16/09/2011 14:06 Sheet: Metal Spinning 57

Volumes of production Tolerances From single prototypes to batch production Because the metal is stretched around the and runs of several thousand. mandrel, the thickness of a part changes Unit price vs. capital investment during the spinning process. The flatter The tools for pushing and the mandrels are the shape, the less the metal will need made from wood or metal, depending on to stretch. the size of the component and the quantity Relevant materials required. For a small number of units it Spinning can be applied to a variety of makes sense to use affordable wooden metals, ranging from soft, ductile mandrels, but for large production runs and aluminum (which are the most metal is a better choice because the former common) to hard stainless steels. will be subject to greater wear. Typical products Speed The kitchen wok is a good example of an Production cycle times are higher than for item made by spinning—it is even possible press forming (see metal cutting, p.59), to see the evidence of its production but setup times are substantially shorter, in the concentric lines on the outside making metal spinning suitable for surface. Other products include bases and prototyping, one-offs, and short-to lampshades for lighting, cocktail shakers, medium-batch production. urns, and a whole mass of industrial Surface components. A spun surface may need to be polished in Similar methods order to eliminate the circular witness lines Spinning is often combined with other on the external surface of the part. techniques to produce more complex Types/complexity of shape products. For example, pressure-formed This is really only a technique for making parts are often spun to create necks, symmetrical shapes that start with a flanges, and flares. Although far less sheet of metal. Disks, cones, hemispheres, common than spinning, incremental sheet- cylinders, and rings are the typical shapes metal forming (p.257) is a new process made using this process. Undercuts and that allows a range of complex forms to be re-entrant angles are achieved by a split created from sheet metal using a single tool. mandrel, which comes apart like the Sustainability issues segments of an orange in order for the Metal spinning is one of the most energy- part to be released. Closed shapes such as intensive processes available as the hollow spheres are made by joining two part needs to be constantly rotated at halves together. a high speed for a long length of time. Scale However, with the formed metal’s high Spun-metal products can be produced strength, parts have excellent durability 3 at less than /8 inch in diameter, and, at which ensures a prolonged life cycle. the other end of the scale, Acme Metal Additionally, at the end of the product’s Spinning in the US has produced a shape lifespan the metal can be melted down that measures almost 11½ feet across. and reused. Further information www.centurymetalspinning.com www.acmemetalspinning.com www.metalforming.com www.metal-spinners.co.uk

LK016_P0036EDmakingIt2us.indd 57 16/09/2011 14:06 58 Sheet: Metal Spinning

external shape of this mandrel. Several operations can be performed in one setup, and work pieces may have pushing tool re-entrant profiles (undercuts). The design profile in relation to the center line is therefore virtually unrestricted, though it will be symmetrical. Sheer and flow forming are advanced forms of spinning that can be used to deliberately alter the wall thickness of metal parts by anything up to 75 percent. It is ideal for concave, conical, and convex hollow parts. metal sheet mandrel

A flat metal sheet is clamped against a mandrel and both are rotated at high speed. The metal is pushed with a tool until it conforms exactly to the mandrel’s shape.

1 Preparation of the 2 The metal is pushed against 3 The metal component taking shape over wooden mandrel. the mandrel as both metal the mandrel. and mandrel are spinning.

– Spinning is a very flexible form – Some materials of mass-production, which can will harden in the also lend itself to small-batch spinning process. production. – Spinning often – Low tooling costs. requires post finishing. – Can generate complex shapes without additional material – The process offers removal (cutting) or joining limited control processes. over wall thickness because of the way the metal is slightly stretched over the mold.

LK016_P0036EDmakingIt2us.indd 58 16/09/2011 14:06 Sheet: Metal Cutting 59 Metal Cutting including press forming, , blanking, punching, bending, perforating, nibbling, and stamping

In the metal industry the term “cutting” is hardly ever used, because technically it is such a broad term it has almost no meaning. Cutting processes can be divided into two main categories: chip-forming and non- chip-forming. Press forming, shearing, blanking, punching, bending, perforating, nibbling, and stamping are all terms that in one way or another describe non-chip-forming of metal sheet. Methods such as milling (see machining, p.18) and turning on a lathe (see p.26), on the other hand, are chip- forming techniques. Punching and blanking are very similar in the sense that they both involve the removal of part of a sheet to form a hole. The processes differ in that punching is used to make sheets with shapes cut out of them, while Product beverage can pull tab Materials aluminum blanking is a process for making Manufacturer Rexam separate shapes, similar to using a Country UK cookie cutter to make many cookies Date 1989

from rolled-out dough. The metal disk, This is an everyday product that has to be super which is the starting point for the cost-effective, yet must work all the time and must beverage can tops (pictured), would absolutely never cut your lip when you drink from it. Press forming and shearing are just two of the have been made using blanking. methods used to make this ubiquitous product. Nibbling is used to cut a sheet in successive bites from a small punch that pulses up and down in a process similar to that of a -machine. Shearing involves a punch and a die with a tight control over the gap between the two (unlike punching, which doesn’t have a die). The terms “perforating” and “bending” should be fairly self-explanatory.

LK016_P0036EDmakingIt2us.indd 59 16/09/2011 14:06 60 Sheet: Metal Cutting

Metal stamping is a cold forming performed either in a sequence or in process that is used to produce one action. A single die is needed for shallow components from metal sheet. each operation, but the component can Although it is a fairly straightforward be removed and placed in another die method of cutting and forming sheet, for additional forming. Progressive it includes several variations, all of dies (like a series of dies) are used in which combine a punching process more complex procedures to form together with a forming process, multiple actions.

Volumes of production Relevant materials The process can be used for manual Restricted to sheet metal. production or for an automated CNC high- Typical products volume production. Cooling fan for electronics, Unit price vs. capital investment washers, keyholes, and watch Tooling costs can be reduced, or eliminated, components. by the use of existing punches or cutters, Similar methods allowing for high-volume production to Laser cutting (p.46) and water-jet cutting be achieved with low capital costs. (p.42) are two non-chip-forming methods Speed that can be set up to produce designs from Varies greatly, but typically 1,500 soda-can CNC programs, without tooling costs. pull tabs can be produced per minute. Sustainability issues Surface Each of the various cutting processes In terms of finishing, these cutting is based on the removal of material, techniques will generally need deburring. which results in a significant amount Types/complexity of shape of waste material. However, metals can Mostly used in the production of small be melted down to form new sheets components, and thickness is restricted that can reused in the process to reduce to available standard sheet. material consumption and the use of virgin Scale resources. Aluminum is one of the most Restricted by the standard sheet widely recycled materials. dimensions. Further information Tolerances www.pma.org High tolerances are achievable. www.nims-skills.org www.khake.com/page88.html

– Very versatile in terms of producing – Parts may be limited different shapes. to stock sizes of material. – Can be used for any solid metal. – Material utilization – High degree of accuracy. can be low due to wastage.

LK016_P0036EDmakingIt2us.indd 60 16/09/2011 14:06 Sheet: Industrial Origami® 61 Industrial Origami®

There is something fascinating and number of operations required to inspiring about watching a simple, shape the metal and the whole process flat sheet of paper being transformed can therefore be completed in much into a complex form through origami. less time and at a much lower cost. In much the same way, this patented The component is created from a net, process takes the principles of origami much like a flattened cardboard box. but applies them on a much more A stamping technique or a laser is industrial scale, using metal in place of used to cut the outline of the shape paper to create usable products. from a metal sheet and to produce This folding innovation has a series of lines and smile-shaped many benefits over traditional metal- curved cuts along the edges to be forming methods such as stamping folded. A set of straps pulls at the smile and press breaking, as it reduces the shapes from either side of the sheet,

Product Jack-stand made with Industrial Origami® Materials 12-gauge cold-rolled steel Manufacturer Industrial Origami Country USA Date 2004

A typical component showing the cutlines and construction method of Industrial Origami®. This jack-stand demonstrates the structural strength that can be obtained using the method.

LK016_P0036EDmakingIt2us.indd 61 16/09/2011 14:06 62 Sheet: Industrial Origami®

to create contact between two of the a single piece, and removes the need sides. This leverage causes the sheet for welding and joining as it uses a to bend along the fold lines with only number of folding clips to secure the a relatively small amount of force. It folds, which significantly reduces is the small smile-shaped cuts that material consumption. The process control and determine the folds as they enables the rapid creation and fold-up direct the stresses during folding to of prototypes, which allows designers make everything align perfectly. to experiment with and test prototype The process allows for the configurations quickly, and make any integration of several parts into necessary changes.

LK016_P0036EDmakingIt2us.indd 62 16/09/2011 14:06 Sheet: Industrial Origami® 63

Volumes of production to any number of materials, including From one piece to millions of pieces. plastics and composites. Unit price vs. capital investment Typical products Investment costs of designing prototype Currently the main applications are productions and for manufacture are high. for engendering components such However, savings on materials, storage, as automotive chassis systems, solar and transportation, and the elimination mounting systems, packaging, cooktops, of secondary fixing processes make the and built-in ovens. process cheaper overall. Similar methods Speed Superforming aluminum (p.70), press Origami features are dependent on the forming (p.59). available punch, laser, or stamping speeds. Sustainability issues Folding is complete in seconds. The sheets are stamped in flat pieces Surface so can be transported flat-packed and Not applicable. folded on arrival. This reduces the space Types/complexity of shape needed during transportation, which Suitable for a range of thicknesses from could potentially allow for greater 1 /100 inch to the limit of any cutting effectiveness of energy use. Additionally, equipment. there is a significant reduction in materials Tolerances consumption as many joints and fixtures Alternative methods of forming in metal are incorporated into the fold design. can produce stack-up errors related to As with any sheet-cutting process there is maintaining dimensional tolerance. a high degree of waste materials; however Industrial Origami maintains the level of these can potentially be recycled. accuracy of the machine that originally Further information applied the lancing. www.industrialorigami.com Relevant materials The process has been predominantly used with sheet metals but it could be applied

– Reduced joining, fixing, and – A great deal of processing. planning is required to make a design – Integrating multiple parts into suitable for the a single sheet means material process. consumption is significantly reduced. – Fast construction and assembly relative to alternative methods of construction. – Allows for effective prototype testing. – Lower labor costs.

LK016_P0036EDmakingIt2us.indd 63 16/09/2011 14:06 64 Sheet: Thermoforming Thermoforming including vacuum, pressure, drape, and plug-assisted forming

Thermoforming is one of the most made of wood, aluminum, or other common methods of producing inexpensive materials. The former is plastic components and any art the exact shape of the part required undergraduate will have used a and is placed at the center of a table, vacuum-forming machine. Vacuum which can be raised and dropped. The forming is one of the few plastic- rigid plastic sheet is heated under a forming methods that is as accessible series of convection bars similar to a to school and college students as it is domestic oven, until the plastic is soft, to large-scale industrial production. pliable, and saggy. At this point, the It is also one the easiest methods of former is raised on its bed, pushing production to comprehend, and if into the soft sheet, and a vacuum is you have ever seen the process in applied. This sucks the air out from operation you will understand why. below and pulls the plastic onto the The basic materials needed for former. Once the plastic has “hugged” this process are a sheet the former and cooled slightly, it can be and a former. Because the pressures removed for post finishing. employed are low, the former can be

Product chocolate-box tray Materials Plantic biodegradable polymer Date 2005

There are few better examples of thermoforming than a chocolate-box tray. The individual shapes of the chocolates are evidence of the shape of the mold that is used to form the trays.

LK016_P0036EDmakingIt2us.indd 64 16/09/2011 14:06 Sheet: Thermoforming 65

Other types of thermoforming it is mechanically stretched, allowing include pressure forming, which the sheet to remain close to its original works in the opposite way to vacuum thickness. Plug-assisted forming uses forming by forcing the material into plugs to prestretch the plastic before the mold. Drape forming, as the name the vacuum is introduced. Again, this suggests, consists of draping a sheet of allows for greater control over the heated plastic over a male mold, where material thickness.

Volumes of production Tolerances Suitable for model-makers’ prototype Varies, depending on size of the formed work and one-offs, but also for large-scale piece. As a guide, a forming of less than 1 production. 6 inches will hold a tolerance of /70 inch. Unit price vs. capital investment Relevant materials Formers can be made from a range of Most thermoplastics that are supplied materials, depending on the number of as sheets. Typical examples include components that is required. The ease of , ABS (acrylonitrile butadiene machining and its wear resistance makes styrene), acrylics, and . aluminum suitable for large production Typical products runs. Epoxy resins are used as a cheap Canoes, bathtubs, packaging, furniture, alternative to aluminum, but anything can interior car trim, and shower pans. be used, including MDF, plaster, wood, and Similar methods even modeling clay, which is excellent for Superforming aluminum (p.70) and vacuum-forming shapes with undercuts, inflating metal (p.76). because you can pick it out afterward. Sustainability issues Speed The low pressure and moderate Bathtubs can be made at a rate of one every temperatures employed during processing, five minutes. Beyond this, speed is difficult to along with fast cycle times, ensure that estimate, because multi-mold formers can energy consumption is low. However, rapidly speed up the process, and, besides additional processing is required to trim this, the thickness of the material affects the excess material and this produces the time it takes to heat up sufficiently. a significant amount of waste plastic. Surface Further heat is needed for these scraps to picks up surface details be melted down and recycled. The nature very well, so the surface finish of the mold of the shapes that are thermoformed is reflected in the surface finish on the part. means components can be nested during Types/complexity of shape transportation, saving on bulk. You will need angles, because Further information undercuts are impossible to achieve www.formech.com with standard tooling. www.thermoformingdivision.com Scale www.bpf.co.uk A 6½ by 6½-foot aperture is standard, www.rpc-group.com but it can be even bigger.

LK016_P0036EDmakingIt2us.indd 65 16/09/2011 14:06 66 Sheet: Thermoforming

1 The former (in this case 2 Once the bed has been 3 The heater is lowered 4 A vacuum is applied to a simple wooden shape lowered, the plastic sheet onto the plastic sheet. form the shape. for a college project) is is placed on top, ready to placed on the bed. be clamped by the metal frame.

Vacuum forming heat thermoplastic clamp sheet sealed chamber

vacuum bed former

1 The former is placed 2 Here, it is covered by 3 The plastic sheet is 4 Once the plastic has onto a bed and lowered the thermoplastic sheet, heated from above until “hugged” the former into a chamber. which is clamped into a it becomes flexible. and cooled slightly, it is metal frame, creating a The former is then removed for finishing. sealed chamber. raised and a pump is activated, resulting in air being drawn from the chamber and the sheet being sucked over the mold.

– Equally suitable for small or large – Requires a secondary production runs. process to trim the sheet. – Low pressure, so tooling can be fairly cheap. – No vertical sides on the finished part; draft – Suitable for in-mold decoration. angles are a must. – Multiple parts can be made using – Can have undercuts, a single multi-former. but these need special tooling.

LK016_P0036EDmakingIt2us.indd 66 16/09/2011 14:06 Sheet: Explosive Forming 67 Explosive Forming AKA High-Energy-Rate Forming

Can you imagine the fun in demonstrates the lateral thinking used discovering this process? In a way it by engineers to pursue new methods reminds me of the British TV-show of making things. character Mr. Bean, who decided to The first use of explosive forming paint his living can of paint. However was documented in 1888, when it unlikely, explosive forming is actually was employed in the forming of plate an established method of forming . The First and Second metal sheet or tube. It is also another World Wars provided an intense great example of a process that period of development, as a result

Product Desert Storm architectural panels Materials coil-coated aluminum Manufacturer 3D– Metal Forming BV Country The Netherlands Date 1998

These architectural panels show the scale of panels and the complex patterns that can be achieved with explosive forming.

LK016_P0036EDmakingIt2us.indd 67 16/09/2011 14:06 68 Sheet: Explosive Forming

of which explosive forming became In simple terms, the sheet or tube is a major process for manufacturing placed in a vacuum-sealed die cavity, missile nose cones in the 1950s. Today, which is in turn placed under water explosive forming exists in two forms (unless it is the open-air method). —“standoff,” in which the explosive is A charge is placed over the sheet positioned at a distance from the metal, and detonated, sending shockwaves either in the open air or submersed in through the water and rapidly forcing water or oil, and “contact forming,” in the material into the die cavity. which the explosive is in direct contact with the metal.

Although this image does not show the close-up workings of the process, it does give some indication of the scale and the sealed, pressurized environment in which the explosive forming takes place.

– It is possible to achieve precise – Limited number of tolerances. manufacturers. – Cost-effective tooling compared – Must adhere to strict to alternatives. safety regulations. – Can reduce the number of operations in the manufacturing process, including welding, due to its ability to form complex parts.

LK016_P0036EDmakingIt2us.indd 68 16/09/2011 14:06 Sheet: Explosive Forming 69

Volumes of production Scale Explosive forming can be used for one- Specific manufacturers can form sheets off art projects such as and of nickel up to an incredible thickness of installations, but it is equally suitable for ½ inch, with lengths of up to 30 feet. mass-production of industrial components. Larger sheets are only achievable by In former East Germany it was used to welding sheets together. make hundreds of thousands of cardan Tolerances axles for heavy trucks. Able to maintain precise tolerances. Unit price vs. capital investment Relevant materials If conventional pressing or spinning can be The process is not restricted to soft metals used, they would usually be cheaper, but such as aluminum, but embraces all relatively low tooling costs and the ability metals, including titanium, iron, and to manufacture complex shapes can make nickel alloys. explosive forming the best option available. Typical products Speed Large architectural components and Varies enormously depending on the size panels, and parts for the aerospace and and complexity of the shape. Sometimes automotive industries. it is possible to manufacture twenty Similar methods small parts in one explosion, while larger, Superforming aluminum (p.70) and more intricate shapes can require up to inflating metal (p.76). six explosions over three days. Even a Sustainability issues single explosion is quite time-consuming, Relatively slow cycle times coupled with however, due to the lengthy setup time intensive energy consumption hinder (amounting to over an hour per explosion). the use of this process for sustainable Surface manufacture. In fact, some larger forms Surface quality is generally extremely good. can require several explosions to deform It is possible to form grade 2G (chemically fully, which further increases energy use. polished) stainless steel without damaging Harmful substances are used to create the even the protective foil, producing parts explosive chemical reaction and need to with a perfect mirror finish. be cleaned before disposal. Types/complexity of shape Further information Ideal for forming complex shapes with www.3dmetalforming.com seamless cavities.

LK016_P0036EDmakingIt2us.indd 69 16/09/2011 14:06 70 Sheet: Superforming Aluminum Superforming Aluminum including cavity, bubble, back-pressure, and diaphragm forming

The process of heating a sheet of when it comes to both materials and plastic, draping it over a mold, and processes. Superforming involves such sucking the air out has been in use an overlap, since it brings traditional for some time (see thermoforming, vacuum forming with plastic to p.64). However, as the speed of aluminum alloys. The process is the development of new materials achieved through four main methods: increases, more technologies overlap cavity forming, bubble forming, back- pressure forming, and diaphragm forming, each suited to specific Product MN01 bike applications. The common element Designer Marc Newson in all these methods is the heating Frame builder Toby Louis-Jensen Materials aluminum of an aluminum sheet to 840–930°F Manufacturer Superform in a pressurized forming oven, and Country UK then forcing it over, or into, a single Date 1999 surface tool to create a complex three- This bike is a good example of the transfer of dimensional shape. industrial manufacturing processes into consumer products by experimental projects. The text embossed onto the frame also illustrates the detail that is achievable.

LK016_P0036EDmakingIt2us.indd 70 16/09/2011 14:06 Sheet: Superforming Aluminum 71

In the cavity method, air pressure bubble. A mold is then pushed up forces the sheet up into the tool in into the bubble and air pressure is a process that can be described as applied from the top, which forces “reverse vacuum forming.” According the material to conform to the to the manufacturers, this process is shape of the mold. Bubble forming ideal for forming large, complex parts is suitable for deep and relatively such as automotive body panels. complex moldings that are difficult In bubble forming, the air to achieve with the other super- pressure forces the material into a .

Cavity forming Bubble forming

mold air pressure aluminum sheet

aluminum sheet

mold air pressure Air pressure blows the sheet into a bubble. A mold is then pushed up into the bubble and In the cavity method, air pressure forces the sheet air pressure is applied from the top, forcing the up into the tool. material to conform to the shape of the mold.

Back-pressure forming Diaphragm forming

air pressure non-superelastic alloy mold mold superelastic alloy aluminum aluminum sheet sheet

air pressure air pressure

In back-pressure forming, pressure is Air pressure forces the heated superelastic employed from both the top and bottom aluminum onto a heated non-superelastic alloy surfaces of the mold. which is then formed over the mold.

– Complex forms can be created – Limited to aluminum within a single component. alloys. – A range of sheet thicknesses can be used. – Can create subtle details and forms, without spring-back issues.

LK016_P0036EDmakingIt2us.indd 71 16/09/2011 14:06 72 Sheet: Superforming Aluminum

Back-pressure forming uses allows for “non-superelastic” alloys pressure from both the top and bottom to be formed. The non-superelastic surfaces of the mold to maintain material is “hugged” over the mold the integrity of the sheet and allow using a combination of a sheet of for the forming of difficult alloys. heated “superelastic” aluminum Diaphragm forming is a process that and air pressure.

Volumes of production Relevant materials At present, production runs of about This process is specifically designed for 1,000 parts are considered large, but mass- use with what are known as “superelastic” production is a possibility, with some types of aluminum. However, the automobile manufacturers starting to diaphragm-forming method enables the use the process on a larger scale. processing of non-superelastic materials. Unit price vs. capital investment Typical products High capital investment, mainly in tooling A large market for this process is in the and material. aerospace and automotive industries. Speed Designers such as Ron Arad and Marc Depends on the material—some alloys can Newson have applied it to diverse be formed in three to four minutes, while furniture and bicycles. On the London the structural alloys used in aircraft, for Underground, architect Norman Foster example, may need up to an hour to form. used superforming to produce tunnel- Surface cladding panels for Southwark station. Excellent surface quality. Similar methods Types/complexity of shape For plastic, vacuum forming (p.64), for This depends on the specific method you glass, slumping (p.52), and for metal, use. Bubble forming allows the greatest look at the inflated stainless steel by degree of complexity in shape, but with all Stephen Newby (p.76). methods the basic principle is about creating Sustainability issues three-dimensional shapes from a flat sheet. The process requires several stages of Draft angles need to be considered in order production, each of which uses significant for parts to be removed from the mold. amounts of energy through high heat and Undercuts are not recommended. pressures. A significant amount of excess Scale material is produced after trimming but can Each method is suited to different scales be recycled back into the process or used and thicknesses of material, for example, elsewhere. Additionally, when the formed using back-pressure forming, parts can product reaches the end of its lifespan be made up to approximately 48 square it can be recycled into new products to feet. Cavity forming can only process reduce the use of raw materials. The nature smaller sheet sizes, although these can of the shapes that are thermoformed 3 be up to /8 inch thick. means components can be nested during Tolerances transportation, saving on bulk. 1 Typically ± /25 inch for larger parts. Further information www.superform-aluminium.com

LK016_P0036EDmakingIt2us.indd 72 16/09/2011 14:06 Sheet: Free Internal Pressure-Formed Steel 73 Free Internal Pressure- Formed Steel

Product Plopp Stool Designer Oskar Zieta Materials stainless steel Manufacturer Oskar Zieta Country Switzerland Date First exhibited 2009

The visual language of these stools refers to the soft forms typical of inflated latex, masking the fact that they are made from stainless steel.

LK016_P0036EDmakingIt2us.indd 73 16/09/2011 14:06 74 Sheet: Free Internal Pressure-Formed Steel

This whimsical and playful process place of plastic to create objects that is a buoyant example of a traditional are incredibly solid and strong. Oskar technique used in an unconventional Zieta, the designer behind the process, way to produce creative and surprising calls it “FIDU,” which stands for free results. It works like inflatable pool inner-pressure deformation (the letters toys or armbands, but uses steel in correlate in his native German). Two sheets of steel are laser cut to produce two pieces that are identical in shape. These pieces are then welded together along the edges by a robot to provide a water- and airtight seal. As the air enters, the sheets begin to deform and expand into a 3-D shape. The result is a light construction, which can be easily mass-customized at low production costs with well-established techniques. This process, with Oskar’s many other sheet-metal-forming techniques, opens up new possibilities for lightweight structures and products that are incredibly strong and stable.

LK016_P0036EDmakingIt2us.indd 74 16/09/2011 14:06 Sheet: Free Internal Pressure-Formed Steel 75

Volumes of production 10 x 100 feet. One of Oskar’s projects for This is limited to batch production from London’s Victoria and Albert Museum was a single company. Oskar Zieta’s creative 100 feet long. process involves a hands-on approach Tolerances where a great amount of experimentation The tolerance is dependent on the and prototyping is carried out with different complexity and the geometry of the shape. shapes to test the behavior and possibilities Relevant materials of the steel. Therefore this is a process Sheet steel and plastics. that is suited to one-off or large-scale Typical products batch production. The process had predominantly been Unit price vs. capital investment used to produce furniture, including Laser technology is still expensive but the stools, chairs, and benches. However, this difference between price of the material innovative technique has now found its per pound and laser generator has changed way into the development of wind turbine dramatically in the past five years. Cheaper rotor fins, structural forms such as bridges, lasers will mean that this technology will exhibition pieces, and even bike frames. be used more frequently in future. The Similar methods numerous prototyping and product test Superforming aluminum (p.70), impact steps require a lot of setup time to develop extrusion (p.146), press forming (p.59). a design, so both lead times and costs are Sustainability increased; however, in many cases tooling Material consumption is low as the steel is kept to a minimum. structures are hollow yet stable and Speed strong. Apart from the sealing of the It takes 21 minutes to make one of metal edges no heat is required. the stools. Further information Surface www.zieta.pl All of the common surface treatments— www.nadente.com polishing, powder-coating, lacquering, www.blech.arch.ethz.ch enamel-coating, gumming—can be used to treat the surface. Scale Steel-sheet coils are up to 2½ miles long, the largest nonstandard sheets are

– Produces comparatively – There are several lightweight structures from a rigid, stages of production thin material (laser cutting, welding, forming), – Products are highly customizable. which increases lead times.

LK016_P0036EDmakingIt2us.indd 75 16/09/2011 14:06 76 Sheet: Inflating Metal Inflating Metal

From its extraction when creating hard quality of the steel. The process vacuums to its sudden introduction literally involves inflating two sheets into a pre-form to create plastic bottles, of metal that have been sandwiched air is often a key material in production together and sealed at the edges, methods. In terms of blow forming, without using molds. Each inflated it is thousands of years old, and its piece, therefore, responds in a earliest use was in the forming of different way, producing a unique glass. British designer Stephen Newby, piece. In terms of size, the pieces are however, has recently introduced a only limited by the original sheet way of inflating stainless steel sheet size. A variety of textured and colored to create new possibilities in visual stainless steels can be used—these are language for this hard metal. not damaged in the process because The soft appearance of the inflated the metal is formed from the inside. shapes contrasts with the tough,

Product inflated stainless steel pillows Designer Stephen Newby Materials stainless steel Manufacturer Full Blown Metals Country UK Date 2002

The indentations in these pillow shapes are the natural result of the metal creasing when it is inflated from the two sheets of steel that are sandwiched together.

LK016_P0036EDmakingIt2us.indd 76 16/09/2011 14:06 Sheet: Inflating Metal 77

Volumes of production Relevant materials Best suited to batch production. Most metals including stainless steel, Unit price vs. capital investment mild steel, aluminum, brass, and copper. No tooling, but some designs require Typical products prototyping. Architectural cladding and screens, Speed large-scale public art, outdoor Blow forming (of which inflating metal design, including water features, and is just one example) is instantaneous. contemporary interior products. The process is semiautomated and runs Similar methods at different times according to size. For Glass blowing by hand (p.116) and example, an inflated 4-inch metal square superforming aluminum (p.70). can be produced at the rate of 30 squares Sustainability Issues per hour. Although very hard and rigid, only very Surface thin sheets of steel are used to make these Full range of high-quality factory-applied steel structures, which reduces material finishes, including mirror finishes, colors, consumption without compromising , textures, and embossed finishes. strength. However, the extreme Types/complexity of shape temperatures required for the metal Any shape that can be produced from flat welding, along with the high pressures two-dimensional templates, including required to pump in the air, consume a fair organic forms, figurative lettering, soft, amount of energy. cushion-like creased forms, and smooth, Further information uncreased forms. www.fullblownmetals.com Scale From 2 inches up to the maximum single sheet size, typically 10 by 6½ feet. Tolerances

1 /5 inch per 40 inches in overall dimensions.

– Ability to form unique shapes in – Offered only by a metal. single manufacturer. – High strength-to-weight ratio. – The process can be used to form high-tensile strength materials. – Factory-applied finishes are preserved in the forming process. – Specific dimensions are easily achieved without the need for molds or jigs.

LK016_P0036EDmakingIt2us.indd 77 16/09/2011 14:06 78 Sheet: Pulp Paper Pulp Paper

Paper can be a wonderfully low-tech manufacturing processes to create material and it’s so common, everyday, some exciting new outcomes. This is and often banally dull, that we often a high-tech approach to a low-tech forget its contribution to life simply material for creating semidurable because of its sheer number papier mâché products. The process is of manifestations. based on various methods; in one the Evolved from Swedish press forms layers of paper together company Sodra who produce wood- that have been impregnated with based materials, Pulp Labs are (PLA), a biodegradable creating a whole range of pulp-based material made from corn starch materials and experimenting with or sugar cane. Heat and pressure combine to melt the PLA and bind all the layers of paper together to produce remarkably strong parts. Depending on the geometry of the part, 1 compressed pulp just /12 inch thick is able to support the weight of a person. Due to the fibres being encapsulated by the PLA the material is also unaffected by humidity and heat, and its durability is almost comparable to that of steel, wood, or plastic.

Product Parupu Designer Claesson Koivisto Rune Materials paper pulp Manufacturer Sodra Pulp Labs Country Sweden Date 2009

The Parupu chair combines strong geometry with advanced use of an archaic material. The mold of the chair is dipped into a paper-based slurry, heated in an oven, and then pressed to activate the DuraPulp.

LK016_P0036EDmakingIt2us.indd 78 16/09/2011 14:06 Sheet: Pulp Paper 79

Volumes of production Relevant materials At the time of writing the process is more DuraPulp is made from paper pulp mixed a laboratory project than one for mass- with PLA. production. However, Sodra will work Typical products with designers to help realize products. Products currently being tested are in Unit price vs. capital investment the area of furnishings, such as chairs The cost of a press-forming tool is in the and lighting. region of 50,000 US dollars. Similar methods Speed Molding paper pulp (p.149), paper-based The components have to be left in the rapid prototyping (p.242). press for approximately seven minutes Sustainability issues and a fair amount of handwork is required DuraPulp is made using paper pulp and to finish them. organic plastic both of which are non- Surface toxic and renewable. At the end of its As expected, the surface looks and feels like lifespan the material will biodegrade ultra-stiff cardboard. Colors, approved for without harming the soil, avoiding landfill use in children’s products, are impregnated disposal. However, the process involves within the paper before the forming several manufacturing stages and is quite takes place. heat intensive, so has high energy use. Types/complexity of shape Further information Shapes are based on a standard male and www.sodrapulplabs.com female configuration, so undercuts are not feasible. Scale At the time of writing the maximum size of the press tool is 20 x 40 inches. Tolerances Thickness dimensions are in the range of 1 3 3 /12 inch to /8 inch (although /8 inch has yet to be tested).

– An alternative to plywood. – Process is not yet fully commercialized. – Economical material usage.

LK016_P0036EDmakingIt2us.indd 79 16/09/2011 14:06 80 Sheet: Bending Plywood Bending Plywood

The conversion of a tree into a simple-looking piece of bent plywood furniture involves at least 35 steps. The technique of cross-laminating veneers to produce stable, stiff engineered materials was first understood by the ancient Egyptians, who used the process for making items such as their iconic sarcophagi. The development of modern bent plywood is the result of a range of technological advancements, including the ability to cut the veneers accurately, the presses to laminate them, and the glues to construct them. The processing of most natural materials tends to be concentrated in the locations where the materials originate, and plywood production takes place mainly in northern Europe, North America, Southeast Asia, and Japan. Starting from the point where the veneers have been sliced or rotary- cut from the logs, these large strips are cut into individual sheets, which Product AP Stool are subsequently dried by being Designer Shin Azumi Materials plywood passed through a long chamber, Manufacturer Lapalma srl at the end of which they are stacked Country Italy according to quality. Date 2010 The veneers are fed into rollers This elegant, stackable stool is formed from a single that distribute an even layer of glue sheet of plywood, with the seat and the body of the over each sheet, with the quantity of stool merging seamlessly. The wide spread of the base helps to disperse pressure. glue being determined by the porosity of the wood. The various sheets are then stacked, with the grain running in alternate directions, to form an odd number of layers. The assembled sheets are placed over the female part of a mold, with the male part clamped on

LK016_P0080EDmakingIt2us.indd 80 16/09/2011 16:37 Sheet: Bending Plywood 81

top. The molds allow for an excess to come together from all sides, and a of veneers, which is trimmed to combination of heat and pressure cures form neat edges once the glue has the glue. The part stays in the mold dried. Depending on the shape, a for about 25 minutes, the exact time pressure of several tons is needed depending on the shape. In industrial to compact the sandwich together. production, a CNC (computer numerical The vertical pressure is aided by control) cutter is then used to trim the horizontal pressure, forcing the molds uneven layers to form a clean edge.

Volumes of production Tolerances Jigs can be made up for single profiles in Rather low because of the flexibility of a small workshop. Industrial production the material. setups can produce hundreds of Relevant materials thousands of units. Birch is used in the majority of mass- Unit price vs. capital investment produced furniture, but many other types Jigs for low-volume production can be of wood, including oak and maple, can be expensive due to the labor costs involved. used. Burly woods (the outgrowth of a tree, However, depending on the design, simple also known as the ), including pine, molds can be made that are still economical are not to be recommended, because it is for small production runs or even one-offs. difficult to produce plywood of consistent At the industrial end of the scale, as with quality from them. most other manufacturing processes, Typical products higher tooling costs are balanced by low Furniture, interiors, and architectural unit costs. cladding. Aircraft frames were made from Speed bent plywood during the two World Wars. Cycle times are fairly long because the Similar methods glued veneers have to dry inside the mold Inflating wood (p.184) and pressing before they can be taken out, and the parts plywood (p.86). need subsequent finishing, including edge Sustainability issues trimming, surface treatments, or painting. Wood is a natural resource that is Surface renewable when controlled by a Dependent on the type of wood. sustainable forestry. However, the Types/complexity of shape production of the plywood, and additional Restricted to simple bends in a single forming, is quite energy intensive as the direction. The inherent flexibility of the wood undergoes extensive processing. material can allow for slight undercuts At the end of its lifespan the plywood when removing pieces from the molds. can be recycled. Scale Further information The scale is generally suited to furniture and www.woodweb.com accessories (such as magazine racks). The www.woodforgood.com restriction on size is determined by the size of www.artek.fi the molds and the ability to exert the degree www.vitra.com of pressure needed to compact the layers. www.lapalma.it

LK016_P0036EDmakingIt2us.indd 81 16/09/2011 14:06 82 Sheet: Bending Plywood

male mold glued veneer

veneer

female mold

roller

1 The veneers are fed into rollers, which 2 The veneers are stacked and the distribute an even layer of glue to each sheet. assembled sheets are placed over a female mold and the male part clamped tightly on top. The molds allow for an excess of veneers, which will be trimmed once the male glue has dried. mold

female mold

CNC cutter

3 Pressure is applied to compact the sandwich 4 Once cured, the part is removed and together. The vertical pressure is aided trimmed to form a clean edge. by horizontal pressure, forcing the molds together from all sides.

– Can accommodate a range of – Involves many steps. thicknesses. – Restricted to bends in – Allows for strong, lightweight a single direction. components.

LK016_P0036EDmakingIt2us.indd 82 16/09/2011 14:06 Sheet: Deep Three-Dimensional Forming in Plywood 83 Deep Three-Dimensional Forming in Plywood

This book features a number of new lines, so deeply cut into the individual and radical ways to process plywood veneers that the wood itself almost into ever more complicated and curved falls apart. This gives the veneers forms. One of these is deep three- the elasticity to be bent in different dimensional forming in plywood, a directions without breaking, which is combination of a production method particularly important when bending and a material specifically developed them against the direction of the grain. for the purpose. Using an innovative The individual sheets of veneer are treatment in which the wood fibers glued together in a way that is similar are relaxed, it is now possible to bend to the bent wood process (see p.80), in plywood into wavy shapes that were order to achieve stiffness and strength. once unthinkable. The technology for preparing the plywood was developed by the German manufacturer Reholz®, and it enables the plywood to be molded into a deep, three-dimensional compound curve, which is capable of producing forms that resemble molded plastic rather than a piece of wood. The key to this process, and the first stage in achieving the complex curves, is a series of closely cut, parallel

Product Gubi chair Designer Komplot Materials Walnut veneer Manufacturer Gubi using Reholz® deep 3-D forming technology Country Germany (process) Denmark (chair) Date 2003

The apparently simple curves of the Gubi chair mask the sophistication of this completely new method of forming wood. The compound curves (the seat passes through an almost 90-degree angle) are a result of the ability of this treated ply to conform to far more complex shapes than, for example, the pressed plywood tray (see p.86).

LK016_P0036EDmakingIt2us.indd 83 16/09/2011 14:06 84 Sheet: Deep Three-Dimensional Forming in Plywood

Volumes of production Relevant materials Suitable for mass-production. Although many basic veneers can be used Unit price vs. capital investment for deep three-dimensional forming, it is The process is not cheap, but it is the only important that the veneer should have way to achieve this level of freedom in a straight grain direction and no knots. shaping plywood, which can go a long way High-quality ALPI-veneers are especially in justifying the investment in tooling for suitable (these, recommended by Reholz® large production runs. who developed the technology, are veneers Speed produced by the Italian company, ALPI). The Reholz® process involves several steps, Typical products including the pretreatment of the veneer, Chair seats, plywood bars, bent furniture pressing, and, finally, trimming. The real frames, or, on a larger scale, laminated difference, however, between standard wood structures for use in the construction bent plywood manufacturing (see p.80) and industry. Deep three-dimensional formed the deep three-dimensional forming process plywood can also be used to coat the is just one step—the cutting treatment to housings of medical devices, for example, which the basic veneers are subjected that paneling for MRI (magnetic resonance enables the plywood to be bent. imaging) scanning machines, and in Surface packaging to replace MDF (medium Comparable to any other type of close- density fiberboard), moldings for lights, grained wood surface, which can be stained, and parts of automobile interiors. painted, and coated in a number of ways. Similar methods Types/complexity of shape The manufacturer compares this process The key here is that deep three-dimensional to the deep- of metal sheets. forming allows layers of thin, prepared However, in terms of wood production the veneer to be built up into formed sheets closest method is bending plywood (p.80), of plywood capable of being bent into although this has the disadvantage of previously unachievable curves. Designs being formable in only a single direction. should allow for the component to be The inflated wood process (p.184) separated from male and female molds, developed by Malcolm Jordan allows so there can be no undercuts. similar three-dimensional forms to be Scale produced, but it requires both foam and The scale is limited by the size of the plywood. Pressing plywood (p.86), which veneers available and the molds used is used to make dinner trays and car to form the final shape. dashboards, achieves a similar three- Tolerances dimensional effect, but with much Because of natural variations in the grain shallower results. of the wood, no molding is exactly like any Sustainability issues other and it can be difficult to achieve very Wood is a natural resource that is high tolerances. This can, nevertheless, renewable when overseen by sustainable be dealt with in a number of ways, for forestry. However, production is quite instance by using flexible fixings. energy intensive as several processes are involved in treating and pressing the veneer. Further information www.reholz.de

LK016_P0036EDmakingIt2us.indd 84 16/09/2011 14:06 Sheet: Deep Three-Dimensional Forming in Plywood 85

1 The stack of prepared sheets of veneer 2 The stack of veneers before the male and assembled with the grain running in alternate female molds are brought together. directions.

3 The seat for the Gubi chair, post forming. 4 The seat is ready for the final shaping process, which involves the excess material around the seat being cut away.

– Permits new forms – There are some limitations with to be produced from regard to small radii and other plywood. sharp bends. – Allows wood to enter – Since this is a wood process, markets normally moldings will never be as reserved for metals accurate as, for example, and plastics. plastic components. – Enhances the – Available only from Reholz®, the structural strength originator of the technology. of plywood.

LK016_P0036EDmakingIt2us.indd 85 16/09/2011 14:06 86 Sheet: Pressing Plywood Pressing Plywood

The first noteworthy thing about arranged with the grain running in this production method is that the alternate directions and with sheets products it is used for are formed by of glue-impregnated paper in between a method that is more reminiscent of each sheet. A melamine-impregnated plastic forming than wood forming. sheet is added to the top and bottom By that I mean that they are formed of this stack, like the bread in a from a flat sheet of wood into a three- sandwich. The sandwiched packs are dimensional shape in a way that gives then placed in a press, in between results similar to shallow plastic male and female molds, where vacuum thermoforming (see p.64). pressure is applied for approximately The first stage of the process for four minutes at 275°F. It is important making the archetypal trays you find for the veneers to have a good degree in cafeterias around the world involves of moisture to prevent the wood from the raw material of veneers being cut splitting. Once removed from the and trimmed into square sheets. In press, the trays are stored on a flat most cases a single layer of veneer table and held down with weights will be made up of two narrow leaves to ensure that they do not warp. The which are “sewn” together with a final stage involves the edges being flat, crosshatched thread of glue. trimmed and sealed with a spray of The sheets are stacked together and a clear lacquer.

Product dinner tray Designer not applicable Materials lacquered birch Manufacturer Neville & Sons Country UK

This sequence of images shows the layers of veneers and glue-impregnated paper; a pressed, untrimmed plywood tray; and the trimmed, lacquer-sealed tray.

LK016_P0036EDmakingIt2us.indd 86 16/09/2011 14:06 Sheet: Pressing Plywood 87

The combination of heat, several years. Today, they are one pressure, and adhesive enables a of the few remaining UK-based range of laminated wood products to companies still producing wooden be produced, resulting in thin-section laminated trays. It is through the designs that can be extremely strong. action of heat and pressure that they Neville and Sons in the UK have been can make durable trays of only about 5 making an assortment of trays for /8 inch deep.

Volumes of production Tolerances As many as 600 wooden trays can be Not applicable. produced in a day. Minimum orders from Relevant materials Neville and Sons are 50 units. Most veneers are suitable. However, the Unit price vs. capital investment material used for trays is generally birch, An affordable ratio for small-scale production beech, or mahogany. makes this method of forming highly Typical products suitable for small- and large-scale runs. Given the shallowness of the depth Molds for trays are produced in aluminum achievable, this process is limited to covered in a stainless steel sheet, which products such as trays and automotive makes them cost-effective even for batch trim with the kind of walnut effect you production. Unit prices are very low. would expect to find in high-end brands. Speed Similar methods One tray can be produced every five minutes. A process that allows for much more depth Surface and possibilities with curving plywood is The surface color, and to a degree the deep 3-D-forming (p.83). Also relevant, but finish and pattern, are controlled by the using a completely different technology, melamine sheet that is used in the pressing is the inflated wood by Curvy Composites process. Decorative patterns, colors, and (p.184). nonslip surfaces are available. Sustainability issues Types/complexity of shape The crossdirectional grain structure of Embossed sheets with a fairly low- plywood minimizes material consumption draw impression, up to a maximum of while maintaining excellent strength. approximately 1 inch. Pressing the plywood in the form of the Scale tray featured here requires a number of Neville and Sons can produce products processes, including a fair amount of heat measuring up to 23½ by 17½ inches. to melt and bond the glues and veneers. Further information www.nevilleuk.com

– Extremely durable: heat-resistant – Difficult to produce and dishwasher-safe. deep impressions. – Excellent chemical resistance. – Printable surface.

LK016_P0036EDmakingIt2us.indd 87 16/09/2011 14:06 3: Contin

90 Calendering 92 Blown Film 94 Exjection® 96 Extrusion 99 Pultrusion 102 PulshapingTM 104 Roll Forming 106 Rotary Swaging 108 Pre-Crimp Weaving 112 Veneer Cutting

LK016_P0088EDmakingIt2us.indd 88 16/09/2011 14:20 nuous

Components that are made from continuous lengths of a material

This chapter looks at components that are made according to the same principles that are used to make sausages, or, in other words, components that are the result of material being fed through a shape to produce long lengths of the same profile. It also looks at continuous strips of wood and plastic, woven lengths of metal, and continuous lengths of bent steel. It celebrates a rich assortment of processes that use a range of dies to form materials that can be produced in infinitely long length but which, with one exception, have the same cross-sectional shape along the whole length. Many of these processes are extremely cost-effective because they can produce identical multiples, cut from the same strip or section.

LK016_P0088EDmakingIt2us.indd 89 16/09/2011 14:20 90 Continuous: Calendering Calendering

Calendering has traditionally been volumes of PVC sheet at a fast rate. used as a finishing process applied In the realm of plastic production it to textiles and paper, using heat and competes with extrusion (see p.96) pressure to give a smooth, shiny surface. in the production of both rigid and In the nineteenth century, however, it flexible plastic sheet. was developed so that multiple rollers When it is used in this sort of could produce rubber sheet. It is a plastic production, the setup usually large-scale process, both in terms of the includes at least four heated rollers, volumes it can produce and the sheer rotating at different speeds. Before size of the machine that is used to this, however, hot granules of the form the sheet material itself (or to add plastic are fed into a kneader where texture to existing sheet materials). they reach a gelling stage. They are Imagine a machine that has at its then fed, via a conveyor belt, through heart a series of steel rollers resembling the first of the heated rollers. The a clothes mangle, that press materials rollers are carefully controlled to into continuous lengths of thin sheet. produce the correct thickness and Although still used for finishing paper, finish. Embossing rollers can be used some forms of textiles, and various to add texture and the sheet material types of elastics, calendering is the then passes through cooling rollers preferred method for forming high prior to being wound onto a giant roll.

The essence of calendering is captured in this image, which shows a ribbon of plastic being passed over polished steel rollers to form a continuous length of plastic sheet.

LK016_P0088EDmakingIt2us.indd 90 16/09/2011 14:20 Continuous: Calendering 91

Volumes of production Relevant materials Because of the setup costs and running Calendering can be used for a range of times involved, tooling is expensive, making materials, including textiles, composites, calendering exclusively a very high-volume plastics (mainly PVC), or paper, where it production process. The minimum length is used to smooth the surface. for production varies between 6,500 and Typical products 16,400 feet, depending on the gauge Paper, used for newsprint, and large-scale of the sheet. plastic sheet or film. It can also be used Unit price vs. capital investment as a finishing process for other Calendered sheets are often further and textiles. converted in order to be turned into Similar methods products, but the price of the sheet before In terms of plastic production, extrusion it is converted is highly cost-effective if (p.96) is the closest comparable method large enough orders are fulfilled. Capital for producing continuous sheet material. investment is extremely high. There is also blown film (p.92). Speed Sustainability issues Once the process is running at optimum Calendering is a largely automated speed—which can take several hours to process that requires continuous heat and achieve—it is superfast. rotation and so relies on large amounts Surface of power. However, the machines operate The rollers can be ultrasmooth to give a at incredibly high speeds to reduce cycle shiny surface, or embossed with patterns times which maximizes this energy use. that are transferred onto the final sheet. Excess material is minimal. Types/complexity of shape Further information Flat, thin sheet. www.vinyl.org Scale www.ecvm.org The thickness of a PVC sheet is generally www.ipaper.com 1 1 between /425 and /20 inch. The width of the www.coruba.co.uk rolls is up to 60 inches. Tolerances Not applicable.

– Produces long, continuous rolls – Suited to very large- without joins. scale production only. – Excellent method for producing large quantities of flat sheets.

LK016_P0091EDmakingIt2us.indd 91 16/09/2011 16:42 92 Continuous: Blown Film Blown Film

The best way to summarize the blown- which are heated (1) and fed film process is to think of blowing vertically by a stream of air through bubblegum, but on a giant industrial a horizontally placed cylindrical die scale. Producing plastic that is on the (2), to form a thin-walled tube that is physical scale of a building involves blown to form a huge plastic bubble a massive tubular bubble of inflated (3). This bubble is fed vertically by plastic being blown upward into a a stream of air in the top of the die to vertical scaffolding structure. form a tower of plastic (4). Varying the The technique takes its name volume of air in the bubble controls from the action of the plastic granules, the thickness and width of the film,

(6)

(5)

(4)

(3)

(2)

(1)

(7)

LK016_P0088EDmakingIt2us.indd 92 16/09/2011 14:20 Continuous: Blown Film 93

which gradually cools as it rises, onto a giant roll, ready for despatch (7). tapers, and, several feet up, eventually The edges of this sheet material can be subsides completely into a flattened trimmed off to produce sheets, or it can tube (5). This flat tube passes through be left as a tube to be used for plastic a series of rollers on its way back down shopping bags and garbage bags. to ground level (6), where it is wound

Volumes of production Relevant materials This is a high-volume method with a The most common materials are high- capacity to convert 550 pounds of plastic and low-density polyethylene, but other per hour. materials, such as polypropylene and Unit price vs. capital investment , can also be used. High capital costs, but extremely cost- Typical products effective for large production runs. Most products—garbage bags, Speed shopping bags, sheeting, , Up to 430 feet per minute. laminating film, and just about any other Surface type of film you care to mention. Controlled by various factors, including Similar methods the material and machinery setup. Extrusion (p.96) and calendering (p.90) Types/complexity of shape are both used to produce thin flat sheets. Flat sheets or tubes only. Sustainability issues Scale The blown-film process is capable of Blown films range from 20 inches producing incredibly high volumes of to 16 feet in diameter, and can be up to plastic film at a very fast rate for minimal several hundreds of feet in length. Films cycle times and therefore minimal energy are available in thicknesses of from 10 or 20 consumption. However, energy use is still microns up to 250 microns. substantial due to the high temperatures Tolerances involved and the constant high pressures This process can achieve high tolerances, that are required for working. Excess but you should be aware that some waste material is minimal. manufacturers offer two grades of blown Further information film—with and without thickness control. www.plasticbag.com www.flexpack.org www.reifenhauser.com

– Allows for the – Blown film is not always ideal production of a —for example, the process of material with casting film can be a better option uniform properties for applications that require high across the whole optical clarity. length and width.

LK016_P0088EDmakingIt2us.indd 93 16/09/2011 14:20 94 Continuous: Exjection® Exjection®

Injection molding and extrusion are mold it begins to fill the hollow space. both vital manufacturing methods As this space begins to fill, the end of for numerous plastic and metal the cavity starts to move horizontally products. However, there are certain along the full length of the mold at limitations to the types of product each the same speed at which the plastic is can be used to produce. For instance, being injected. As the cavity moves, extrusion allows for long, thin parts more of the mold is exposed for the to be created but the entire length of molten plastic to flow into. With the the strip must have a single profile cavity moving and the plastic being shape, which means variations along forced in at the same speed, a high the piece cannot be produced. In pressure is maintained which enables contrast, complex shaped pieces such the consistent flow of the plastic as ledges or closures can be created without shrinkage. It might help to with injection molding, but only in imagine filling a syringe. As you pull short lengths as the resin will not flow the back of the plunger, the pressure throughout long stretches without pulls the liquid into the container, evidence of in the final and the more you pull back, the more component. Exjection® brings together area there is for the liquid to fill. The the benefits of both processes in absence of air creates a vacuum which components that are not only long but is under high pressure. have variations and detailing along the When the mold is completely length of the part. full, the molten plastic is left to cool The process relies on much and set before it is removed and the the same principles as conventional cavity set back to its starting position injection molding where molten for the next cycle. Material type and plastic is forced into a mold. However, wall thicknesses have an impact on the the addition of a movable cavity makes speed of production as they affect how the process a little more interesting. As quickly the cavity can move. the molten plastic is injected into the

Product An Exjection® sample Materials POM (although Exjection® can be applied to a range of plastics) Manufacturer Exjection® Country Germany Date Exjection® was first presented in 2007

Sample of an Exjection® molding that shows the small supports that cut cross the length. Conventional extrusion does not allow for this type of detail over a continuous shape.

LK016_P0088EDmakingIt2us.indd 94 16/09/2011 14:20 Continuous: Exjection® 95

Volumes of production Relevant materials Comparable to injection molding. A wide range of commodity and Unit price vs. capital investment engineering thermoplastics have been The per unit cost of Exjection® molding is successfully processed. The over-molding comparable to that of a traditional injection of metal and wood is also a possibility. molding. However, the initial investment Typical products costs are higher her because of the The process is ideally suited to producing movable cavity. long, thin-walled parts, such as LED Speed lighting strips, lamp covers, and cable The type of material and the wall thickness ducts with integrated moldings such as of the part define the speed of the cavity’s closures and caps. movement and thus the cycle time. Similar methods Surface Exjection® is a proprietary process and Comparable to the high surface finish that there are no comparable methods. is available from conventional injection Sustainability molding. Exjection® allows for several processes to Types/complexity of shape be combined in one single cycle, which Exjection® allows for multicavity eliminates the need to transport parts components, which means combined between manufacturers, and so decreases components can be manufactured in one emissions in addition to reducing lead time cycle. It also allows for over-molding. and therefore energy use. Scale Further information Can vary widely. www.exjection.com Tolerances

1 ± /250 inch.

– Allows continuous profiles to be – Limited to a produced on an injection-molding small number of machine. manufacturers. – Can cost less than comparable alternatives.

LK016_P0088EDmakingIt2us.indd 95 16/09/2011 14:20 96 Continuous: Extrusion Extrusion

Extrusion occurs in a variety of The project follows the simple premise forms, from the low-tech squeeze of how can you make a seat, legs, of a toothpaste tube and the making and back rest from a single shape in of foods such as long-stranded pasta, a single materials and eliminate any to aluminum window frames and the connectors or additional components. continuous lengths of hard-boiled egg Heatherwick sought the largest that McDonald’s slices into its salads. extrusion machine in the world in In the simplest terms, extrusion is order produce his vision. The piece about squeezing a material through a also required a lot of polishing in order hole in a die and producing continuous to transform the dull aluminum into lengths of material at whatever profile a mirror-bright surface. that hole has. The piece captures the essence This bench, or chair depending of the continuous nature of the on the length you cut it, designed by production process, showing the Thomas Heatherwick shows a very unfinished tail that twists into space. large-scale example of extrusion.

Close-up of extrusion die. Detail from extrusion emerging from die.

LK016_P0088EDmakingIt2us.indd 96 16/09/2011 14:20 Continuous: Extrusion 97

Product Designer Thomas Heatherwick Materials aluminum Manufacturer Haunch of Venison Country UK Date 2009

Apart from the large scale of this piece, the most wonderful aspect is the reminder of the extrusion process in the tail. It illustrates an aspect of extrusion that is always cleaned up and never seen.

LK016_P0088EDmakingIt2us.indd 97 16/09/2011 14:20 98 Continuous: Extrusion

Volumes of production Typical products Different manufacturers have different Everything from architectural and furniture minimum lengths, but extrusion can be a components, lighting, and accessories, cost-effective process for both batch and to pasta, and sticks of English rock candy large-scale runs. It is definitely not for one- with place names written through them. offs—unless your one-off is 150 feet long. Similar methods Unit price vs. capital investment Pultrusion (p.99), calendering (p.90), Conventional extrusion requires a low coextrusion (multiple layers of extruded investment in tooling when compared with material in the same component), injection molding (see p.196), for example. laminating (two, or more, materials Speed bonded together), roll forming (p.104), Up to 65 feet per hour. and impact extrusion (p.146). Surface Sustainability issues Excellent. There are multiple forms of extrusion, but Types/complexity of shape both hot and cold extrusion require either No problems in making complex shapes with high temperatures or pressure, which can varying wall thicknesses, just as long as the be energy intensive. Extrusions can crack shape is the same along the whole length. internally during forming when too much Flat sheet can also be produced. heat or pressure is applied, so parts must Scale be monitored closely to prevent waste of Depends on the type of extrusion. Most materials. The nature of the long lengths manufacturers have an average maximum of extrusions also means parts need size of 10 inches in cross-section. The post-cutting in order to convert them length is limited by the size of the factory. into usable shapes. Tolerances Further information Difficult to maintain high tolerances due www.heatherwick.com to a wearing of the die. www.aec.org Relevant materials Extrusion is a versatile process and can be used for materials including wood-based plastic composites, aluminum (shown in this example), , copper, and a wide variety of plastics and ceramics.

– The best way to make long – Parts often need strips with the same profile. to be cut to length, assembled, or drilled. – Can be used for a range of materials. – Extensive production base.

LK016_P0098EDmakingIt2us.indd 98 09/11/2011 13:34 Continuous: Pultrusion 99 Pultrusion

Pultrusion is much less common as a plastic-processing method than its more familiar relative, extrusion (see p.96). The processes are similar in that they allow continuous lengths of a set and an unchanging profile to be formed, but one of the main differences between them is that extrusion can be used for aluminums, wood-based composites, and thermoplastics, while pultrusion is used in the forming of composites that use long strands of fiber as reinforcement. As the name suggests, the process is based on pulling the blended materials of the composite through a heated die. This differs from extrusion, which is based on pushing the material. The continuous lengths of reinforcing fibers, which can be made from glass or carbon, are saturated with a liquid resin mixture as they are pulled through the die, which, Product sample of pultruded besides shaping the component, also composite profile acts to cure the resin as it is heated. Materials glass fiber and resin Sometimes, pre-impregnated (“pre- composite Manufacturer Exel Composites preg”) fibers are used, removing the Country UK need for a resin bath. Manufacturers of plastics have, These profiles illustrate two of the key properties of pultrusion: first, its ability to produce shapes in in recent years, experimented with plastic having similar properties to metal profiles; many applications that traditionally secondly, its capacity to have molded-in colors. used metals, and pultrusion is a typical example of the benefits such experimentation can bring. Pultruded plastics display an increased range advantages of low weight and of physical properties that can corrosion-resistance. benefit both engineering and design are incredibly dense, hard, and rigid applications, because they offer sections—they even “clank” like the toughness of metals with the pieces of metal when you knock them!

LK016_P0088EDmakingIt2us.indd 99 16/09/2011 14:20 100 Continuous: Pultrusion

Volumes of production Relevant materials Depends on the size and complexity of Any thermoset polymer matrix that can the shape—around 1,500 feet is a typical be used with glass and carbon fiber. minimum run. Typical products Unit price vs. capital investment Applications for pultrusions are varied The cost is lower than that for some and include permanent and temporary molding processes, injection (see p.196) structural components for industrial plants, and compression molding (see p.174), vandal-resistant indoor and outdoor public for example, but higher than for, say, hand furniture, and fairground and exhibition lay-up molding (see p.152). stands. Smaller-scale applications include Speed electrically insulated ladders, ski poles, Depends on size, but, as a rule of thumb, it racket handles, fishing rods, and bicycle is possible to achieve 20 inches per minute frames. Perhaps surprisingly, pultruded for a profile measuring 2 by 2 inches, plastics have a resonance similar to 4 inches per minute for chunky shapes and certain woods, which has led to them 40 inches per minute for narrower sections. being used as replacements for hardwood Surface frames for xylophones. The surface finish can be controlled to a Similar methods degree, depending on the reinforcement Extrusion (p.96) and PulshapingTM (p.102). and polymer. Sustainability issues Types/complexity of shape Parts can be produced with thin wall There are no problems with undercuts in thicknesses as a result of the fiber pultrusion. Virtually any type of shape that reinforcement, which minimizes material can be squeezed through the die can be use without compromising strength. made, bearing in mind that the shape must However, as the process is entirely have a constant thickness. automated and heat intensive, energy use Scale can be quite high in relation to the fairly The maximum size for profiles is typically slow cycle speed. The combination of 47 inches wide, although there are materials makes the composites specialist machines that make larger nonrecyclable. components. Minimum wall thickness Further information 1 is approximately /10 inch. The size of the www.exelcomposites.com manufacturing plant dictates the limit to www.acmanet.org/pic the length of the pultrusion. www.pultruders.com Tolerances Vary depending on the profile, but on a standard box-section, with a wall thickness 1 1 of /5 inch, the tolerance is ± /75 inch.

LK016_P0088EDmakingIt2us.indd 100 16/09/2011 14:20 Continuous: Pultrusion 101

1 Individual strands of fiber are fed into a die where they will 2 A finished tube emerges through the cutter, be soaked in resin and formed into their final profile. ready to be cut to length.

Continuous lengths of “pre-preg” fibers are pre-preg pulled through a die. This action shapes the fibers component, and also acts to cure the resin carding as it is heated. plate end heater product die puller cutter

– Offers a 75 to 80 percent weight – A drawback with reduction on steel and 30 percent pultrusion is that the on aluminum. design is restricted to profiles with – Greater dimensional stability than a constant cross- its metal counterparts. section. – Can be colored without the problem of chipping because the color is added to the polymer itself. – Surface decorations can be applied to mimic grain and other textures. – Nonconductive and noncorrosive.

LK016_P0088EDmakingIt2us.indd 101 16/09/2011 14:20 102 Continuous: PulshapingTM PulshapingTM

PulshapingTM is one of the newest continuous processing of components additions to the manufacturing world in fiber-reinforced plastics. For example, and the processing of composites. a round profile can be a constant cross- Developed by US-based Pultrusion section along the majority of its length, Dynamics, Inc., it addresses one of and can then be transformed to a square the biggest problems—the constant, at one end and an oval at the other, unvarying cross-section along the using appropriate tooling. A particular whole length—in the pultrusion advantage of this process is that it process (see p.99). PulshapingTM allows can, for example, allow tube ends to designers to modify a cross-sectional be shaped with threaded fasteners or shape in three dimensions during expansion–reduction couplings joints.

compression mold

pultrusion die

1 A standard pultrusion die is used to form 2 A two-part compression mold is used a cylindrical cross-section. to apply pressure and thereby squash the cylindrical walls.

3 The pressure forms the tube into the desired 4 The finished part has been “morphed” from cross-section. the cylindrical to the new cross-section.

LK016_P0088EDmakingIt2us.indd 102 16/09/2011 14:20 Continuous: PulshapingTM 103

Volumes of production Scale Still in its developmental stage, Ideally suited to long products, more than PulshapingTM , like conventional pultrusion 6 feet. (see p.99), is potentially a high-volume Tolerances production process. Very fine tolerances. Unit price vs. capital investment Relevant materials PulshapingTM is a fairly costly process and Thermosetting resins with glass, carbon, is not suited to small production runs. or aramid fiber. Economic quantities are in excess of Typical products 6,500 linear feet. Components such as handles for large Speed tools, which typically require the main Typically 1½–3 feet per minute for the body to be straight, with end features to continuous pultrusion part of the process, be produced in separate processes, can plus an additional 1–3 minutes for be made in one go with PulshapingTM. reshaping cycles. Similar methods Surface There is nothing really similar to this As in pultrusion, the surface finish can be process in the sense that similar methods, controlled to a slight degree of variation, such as extrusion (p.96) and pultrusion depending on the reinforcement and (p.99), do not allow for manipulation of the polymer. Due to the ability of the process to cross-section. allow manipulation of form along the cross- Sustainability issues section surface, features such as dimples As with pultrusion, parts can be produced and projections can be designed into the with thin wall-thicknesses as a result product in the reshaped segment. of fiber reinforcement, to minimize Types/complexity of shape material use while optimizing strength. This process is highly versatile because The combination of materials makes the of its ability to produce a variety of cross- composite nonrecyclable. sectional shapes. Further information www.pultrusiondynamics.com

– Shares the many advantages listed – Although the for pultrusion (see p.99). geometry can be altered along – The added advantage is that the length of the the geometry can be changed component, this is at selected locations along the restricted to a repeat continuous length of a component. pattern. A continuous curved shape or continuous taper cannot be executed with this method.

LK016_P0088EDmakingIt2us.indd 103 16/09/2011 14:20 104 Continuous: Roll Forming Roll Forming

Roll forming can be used to produce shaped rollers. Feeding the sheet in continuous lengths of anything from a straight line between the rollers simple shapes in a single operation to forces the material to bend into the quite complex profiles that require a required profile. The bending occurs number of passes through different progressively over the series of rollers, rollers, from square sections to round in a process that may require up to shapes and from folded flanges to about 25 different rollers, depending box sections. on the complexity of the profile. Roll In simple terms, roll forming forming can be achieved either as a involves passing a continuous sheet cold forming process or with heat. of metal, plastic, or even glass, over In the case of glass, the sheet passes or through a series of at least two through the rollers as a molten ribbon.

1 A very crude setup, but this 2 As the distance between shows a flat strip of metal fed rollers is closed for this into rollers to be bent into a second pass through the fairly shallow radius. rollers, so a curve with a tighter radius is achieved.

Product Apple iMac aluminum stand Designer Apple Design Studio Materials aluminum Date 2004

The aluminum stand for this iMac illustrates, in a discreet way, Apple’s achievement in exercising extremely tight control over the manufacturing of their products. The achievement here is in being able to bend such a thick piece of aluminum without any tearing of the material at its widest radius, which would normally be associated with this thickness of material at this scale.

LK016_P0088EDmakingIt2us.indd 104 16/09/2011 14:20 Continuous: Roll Forming 105

Volumes of production Tolerances

1 1 High-volume mass-production. Vary between ± /500 and ± /25 inch, Unit price vs. capital investment depending on the thickness of the sheet. Setup and tooling costs are high, which Relevant materials is why the process is suited to mass- Roll forming is almost exclusively used production. It is, however, possible for for forming metals, but it is also a useful small prototypes to be produced in a small process for glass and plastics, albeit on workshop, depending on the complexity a much smaller scale. of the shape. Typical products Speed Automotive parts, architectural profiles, Production speeds are typically 1,000 to window and picture frames, and guides for 2,000 feet per hour for a medium-sized sliding doors and curtain rods. In the case manufacturer, depending on the complexity of glass, the process is employed to make of the profile and the gauge of the material. U-shaped glass profiles that are used Larger manufacturers can often go faster, in architectural glazing. but minimum quantities and lengths apply. Similar methods Surface For metalwork, similar methods include Other operations, such as punching and sheet-metal forming (p.50) and extrusion embossing, can be incorporated into the (p.96), both of which also provide long process to allow for surface details. lengths of a profiled shape. Types/complexity of shape Sustainability issues Long lengths of the same profile, which can Roll forming is a straightforward heatless be quite elaborate. process that produces little waste Scale material and has a fairly quick cycle rate For mass-produced components the standard that minimizes energy consumption. depth is approximately 4 inches, but it However, when using metals roll forming is possible to produce extremely large can in some cases cause microcracks and pieces, as demonstrated by the famous thinning, so sufficient testing should be monumental curved steel structures by carried out prior to production. the artist Richard Serra. In theory, the Further information only thing that dictates the length is the www.graphicmetal.com physical size of the manufacturing plant. www.crsauk.com www.pma.org www.britishmetalforming.com www.steelsections.co.uk www.corusgroup.com

– Flexible in terms of finished – Limited to an length. unvariable thickness of material.

LK016_P0088EDmakingIt2us.indd 105 16/09/2011 14:20 106 Continuous: Rotary Swaging Rotary Swaging AKA Radial Forming with stationary-spindle and flat swaging

To explain this process in very simple dies perform a hammering action at a terms, rotary swaging is used to alter rate of up to approximately 1,000 hits the diameter of a range of metal tubing, per minute, basically battering the rods, and wires. The process involves work piece into shape. the original material being fed through Other forms of rotary swaging a series of rotating steel dies, which include stationary-spindle swaging, form the material to the required which is used to form nonround parts. profile (which is always symmetrical Flat swaging is used to reduce the and round). As they are rotating, the overall thickness of sheet metal.

(1) (2) (3)

The original-diameter material is fed into a rotating steel die (1). This the material into shape with a series of backers (2), which hit the rollers as the piece rotates. The hammering takes place when the backers pass over a series of rollers (3). Simple centrifugal forces allow the backers to recede from the die before once again being pushed forward as they pass over the rollers.

LK016_P0088EDmakingIt2us.indd 106 16/09/2011 14:20 Continuous: Rotary Swaging 107

Volumes of production Tolerances Medium to high levels of mass-production. Good control of both the inside or outside Unit price vs. capital investment diameter, depending on how the dies Although the process sounds complicated, are set up. it is actually based around a very simple Relevant materials principle that involves minimal tooling and Ductile metals are the most commonly fast setup times. This makes it unusual in used. Ferrous metals with high carbon that it is a high-volume process that is also contents can be problematic. cost-effective for short runs. Typical products Speed Golf clubs, exhaust pipes, screwdriver Simple shapes can be produced at a rate shanks, furniture legs, and rifle barrels. of 500 units per hour. Similar methods Surface Machining (p.18), impact extrusion (p.146), Rotary swaging gives an excellent, shiny and deep metal drawing (used to stretch a surface as a result of the hammering, which metal sheet into a variety of hollow shapes, acts to buff the surface. The finish is better such as cylinders, hemispheres, and cups). than stock tubing that has not been swaged. Sustainability issues Types/complexity of shape Rotary swaging is most commonly cold- Because of the action of the rotating tool, worked so does not require heat, which options are limited to symmetrical and means energy use can be significantly round shapes. All shapes of tubing, rod, and reduced. Additionally, there is no loss of wire can be converted into round profiles material during manufacture and parts using this process, but stationary-spindle have increased strength after being swaging needs to be used to obtain non- worked, which improves durability and round sections. product life-expectancy. Scale Further information Depending on the type of machinery www.torrington-machinery.com available at the manufacturer, dimensions www.felss.de 1 can vary from /50 up to 13¾ inches. www.elmill.co.uk

– A large range of symmetrical – Rotary swaging is profiles can be formed. limited to forming round, symmetrical – Because no metal is removed, shapes (stationary- the process is economical in its spindle swaging, use of material. however, can achieve – It is possible to achieve a fine nonround shapes, degree of dimensional control including squares of both the inside and outside and triangles). surfaces. – Reduction of diameter – Working the material hardens it, tends to be easier at thus increasing its strength. the ends than at the middle of the tubing.

LK016_P0088EDmakingIt2us.indd 107 16/09/2011 14:20 108 Continuous: Pre-Crimp Weaving Pre-Crimp Weaving

Pre-crimp weaving is a great case study in how unexpected materials can be woven and used decoratively. In the same way that soft fabrics are woven for decoration, rigid lengths of wire can be woven to dress and adorn our urban landscapes. Industrial weaving takes many forms, from the chain mail of industrial fencing and fabrics to architectural cladding. Although not recognized as a major industrial process, pre-crimp weaving Product architectural mesh can be utilized as a way to design Materials stainless steel and brass Manufacturer Potter & Soar large-scale decorative metal screens. Country UK Date 2005

Architectural mesh can be produced to a wide range of specifications, to increase or decrease density, texture, and transparency. Different optical effects can therefore be created and, in addition, it is self- supporting so it can be used for ceilings and cladding, as well as ornamental balustrading and furniture.

LK016_P0088EDmakingIt2us.indd 108 16/09/2011 14:20 Continuous: Pre-Crimp Weaving 109

LK016_P0088EDmakingIt2us.indd 109 16/09/2011 14:20 110 Continuous: Pre-Crimp Weaving

It is a two-step process. The first In the second step, the long strands of involves lengths of wire being crimped crimped wire are gathered and fed into at specific points. This simple process an industrial heavy-duty loom, where is based on the wire being fed between they are cross-layered with another two rollers, with teeth biting a kink set of pre-crimped wires and woven into the wire at specific distances. into sheets.

1 The lengths of wire are fed into the crimping 2 These toothed cogs show the simple way machine. in which crimping is achieved.

3 Weaving commences on a giant weaving 4 The lengths of woven architectural mesh machine. begin to take shape.

LK016_P0088EDmakingIt2us.indd 110 16/09/2011 14:20 Continuous: Pre-Crimp Weaving 111

Volumes of production Typical products From a minimum of 10 square feet, which Balustrades, external facades, staircase may be expensive, to an unlimited number cladding, sunscreens, and ceilings that of sheets. allow for lighting and sprinkler systems Unit price vs. capital investment to be fitted above. Because of the simple wheels used in the Similar methods crimping, the process does not usually Perforating expanded metal (which uses require tooling. The crimping wheels a single sheet of metal that is then pulled themselves can be cost-effective compared open to create a series of slots, and which with other types of industrial tooling. can sometimes be seen on the median strip Speed on divided highways) and cable mesh— Varies, depending on the type of weave. chain-link fencing that uses wire formed Surface into a spiral, used typically in industrial Good finish, which can also be electro- security fencing. polished (a process that removes microscopic Sustainability issues amounts of material from the metal). Although entirely automated, pre-crimp Types/complexity of shape weaving makes economical use of energy Flat-sheet post forming can result in by crimping the wire in a separate stage infinite possibilities. prior to weaving, to ensure that the wires Scale can be woven evenly and consistently The maximum width is 6½ feet. The when fed into the machine. Additionally, length is restricted by the size of the no heat is required during working, which manufacturer’s site. significantly reduces energy use, while Tolerances the woven form increases the strength and Not applicable. rigidity of the metal to ensure a prolonged Relevant materials product lifespan. Typically uses stainless steel 316L, Further information galvanized steel, or any weavable alloy. www.wiremesh.co.uk

– Adaptable, flexible production – Can form only fixed- quantities. length panels, as opposed to rolls. – Produces a self-supporting rigid screen that can be formed and hold its shape.

LK016_P0088EDmakingIt2us.indd 111 16/09/2011 14:20 112 Continuous: Veneer Cutting Veneer Cutting including rotary cutting and slicing

uses for a tree and it unravels the life of the tree in the process, clearly displaying the evidence of its nutrition and lifespan. There are two main methods for forming veneers: slicing (which involves slicing the tree—or more likely the log—along its length) and rotary cutting (which involves peeling the log in a continuous strip right into its center until nothing is left). Rotary cutting is by far the most common form. Harvested logs are sorted according to quality to be used for veneers, pulp, or conversion to plywood. Depending on the region in which the logs are gathered, they may need to be scanned for metal content. This can often be the result of bullets lodged in the trees during conflicts. Product Leonardo lampshade Once the logs reach the sawmill, Designer Antoni Arola Materials treated wood they are cut down to the required Manufacturer Santa & Cole lengths. These depend on the regional Country Spain standards and whether a log will be Date 2003 used for veneers, or stuck together to This simple, looped lampshade uses veneers in make plywood sheets. The logs are an unusual, decorative way that draws attention then softened by being soaked in hot to the surprising translucency of the wood. water for an average of 24 hours. This loosens the bark and relaxes the fibers in the grain, which makes the peeling It is too obvious to say that trees are process easier. one of the richest sources of materials, Once the bark is removed, the food, and shelter, but, for me, the logs can be slowly dried before, in production of veneers demonstrates rotary cutting, they are set into a the ingenuity and resourcefulness of machine that rotates them while a humans in converting an object into a cutter is introduced to slowly produce variety of usable forms. Peeling a tree a continuous length of veneer. This in continuous strips to create veneers length, and those produced by slicing, has to be one of the most economical can be guillotined into shorter lengths.

LK016_P0088EDmakingIt2us.indd 112 16/09/2011 14:20 Continuous: Veneer Cutting 113

Volumes of production Tolerances Not applicable. Since this is a “commodity,” Not applicable. it is just produced all the time. Relevant materials Unit price vs. capital investment Most tree species. Not applicable. Again, veneers are Typical products produced all the time, so you only pay for The obvious use of veneers is in the tools and machinery indirectly. production of various forms of plywood Speed or veneers for laminating to board for Once loaded into the cutter, a typical furniture makers. However, there are also birch log (with a 12-inch diameter) can be companies that laminate veneers with an completely “peeled” in a continuous sheet adhesive and sell them as wall coverings. in less than two minutes. Similar methods Surface This is a unique method of processing Considering that the process involves a wood. The veneers, however, can be piece of wood that in essence has been cut used to make plywood, which can be with a , the surface is fairly smooth. formed in a number of ways, including Finer finishing can, obviously, be achieved by bending (p.80). by sanding. Sustainability issues Types/complexity of shape Rotary cutting makes the most effective Thin sheet material. use of wood by continuously trimming Scale the log in a full circle using all the wood, The on the cutter can be set to cut whereas the slicing process requires the a varying thickness of veneer from log to be cut into a rectangular piece of 1 1 approximately /25 to /12 inch. The size lumber prior to slicing, which creates of the sheet is determined by the width waste. However, wood is a natural and of the log and at which point the veneer renewable resource so constant regrowth is cut into smaller sheets. A typical log will provide a consistent supply and 12 inches in diameter will produce prevent depletion. up to 50 feet of veneer. Further information www.ttf.co.uk www.hpva.org www.nordictimber.org www.veneerselector.com

– Economical use of the material. – Limited to producing sheets or strips. – Although this is an industrial production method, it has a degree of flexibility, allowing control of the thickness of the veneer and the length and width of the final sheets.

LK016_P0088EDmakingIt2us.indd 113 16/09/2011 14:20 4: Thin & Hollow

LK016_P0114EDmakingIt2us.indd 114 16/09/2011 16:44 116 Glass Blowing by Hand 118 Lampworking Glass Tube 120 Glass Blow and Blow Molding 124 Glass Press and Blow Molding 127 Plastic Blow Molding 129 Injection Blow Molding 132 Extrusion Blow Molding 134 Dip Molding 137 Rotational Molding 140 Slip Casting 143 Hydroforming Metal 146 Backward Impact Extrusion 149 Molding Paper Pulp 152 Contact Molding 154 Vacuum Infusion Process (VIP) 156 Autoclave Molding 158 Filament Winding 161 Centrifugal Casting & 163 Electroforming w

Hollow components with a thin wall section

The longest chapter in the book, this embraces all sorts of processes for forming hollow and, generally, thin-walled shapes. It discusses the many variations of blow molding, a process that has been used for several thousand years to produce priceless handblown glassware. The blow-molding principle has been successfully employed in industrial mass-production, especially by the , which spews out millions of disposable bottles for the soft drinks industry. Other forms of casting and molding are included, from the very common rotational molding, a form of which is used to produce chocolate Easter eggs, to the less common centrifugal casting that hurls metal or glass around a rotating drum forcing the material to attach itself to the walls, to make anything from small pieces of jewelry to huge industrial pipes.

LK016_P0114EDmakingIt2us.indd 115 16/09/2011 16:44 116 Thin & Hollow: Glass Blowing by Hand Glass Blowing by Hand

For at least two thousand years, this technique has been used to make anything from tableware to craft pieces. It involves blowing air through a metal tube to inflate a ball of gathered glass at the end of the tube. Before glass blowing, glass objects were produced by dipping a sand core in molten glass prior to it against a flat surface to control the shape. Once cooled, the sand could be removed, leaving a hollow container. With the introduction of the blowing technique came a whole new set of

1 A mass of molten glass is gathered onto the end of a steel tube, ready to be blown.

Product Air Switch lamp Designer Mathmos Design Studio Materials acid-etched glass Date 2004

Although this light was handblown, the straight sides and symmetrical shape were achieved by blowing into a mold. Usually, the shape of a handblown piece is controlled only by a series of hand tools (as illustrated in the photographs, right).

2 Various hand tools are used to shape the hot glass, in this case a stack of wet fabric.

LK016_P0114EDmakingIt2us.indd 116 16/09/2011 14:37 Thin & Hollow: Glass Blowing by Hand 117

possibilities, not only in terms of shape from lighting to wine glasses. Hand- but also in terms of widening the blown glass constitutes a valuable availability of this material. bridge between mass-produced Today, hand-blowing is still used glassware, which requires expensive industrially to produce a whole range tooling and very high volumes, and of products that are blown into molds, individual one-off pieces.

Volumes of production Relevant materials One-offs and batch production. Any type of glass. Unit price vs. capital investment Typical products The biggest cost is the glass-blower’s Anything from tableware to sculptures. labor. Assuming you want to produce a Similar methods batch of identical shapes, molds can be Lampworking (p.118) and machine-blown used. Depending on exact quantities, glass made using blow and blow (p.120) these will be made from materials offering or press and blow (p.124) molding. varying degrees of longevity, including Sustainability issues wood, plaster, or graphite. As with all glass working, energy Speed consumption is high due to the intense Completely dependent on the scale and heat required over long stretches of time. complexity of the piece, and whether or But because products are shaped by hand not the glass is being blown into a mold. no additional machinery is necessary, Surface which helps to balance energy use. Any Excellent. faulty moldings or broken glass can be Types/complexity of shape melted down and recycled back into For free-blown glass, virtually any shape the process on site to reduce material is possible. consumption. Scale Further information As big as the lungs of the glass-blower will www.nazeing-glass.com allow, bearing in mind that the blower also www.kostaboda.se needs to wrestle with the weight of the www.glassblowers.org/ glass at the end of the tube. www.handmade-glass.com Tolerances Difficult to be precise, because it is a handmade process.

– Flexible enough to produce – Units can be different shapes. expensive due to labor costs. – Can be used for one-off, batch, or medium-volume production.

LK016_P0114EDmakingIt2us.indd 117 16/09/2011 14:37 118 Thin & Hollow: Lampworking Glass Tube Lampworking Glass Tube

There are hundreds of ways of hand- working glass, employing both hot and cold (cutting, for example) processes for making objects without the need for tooling. Lampworking involves the localized heating of a piece of glass to allow it to be pushed, pulled, and generally shaped by a skilled craftsman. The process can be seen as providing a third alternative for shaping glass somewhere between expensive hand forming and mass- production that requires tooling. It is a process that is ideally suited to short production runs. The process starts with a hollow tube of glass, which is set into a slowly rotating lathe. Heat from a blowlamp is applied to specific areas, which are then pushed with a wooden former. Lampworking involves soft, malleable glass being pushed into shape. Depending on whether closed or open forms are required, ends can be left open or rolled round and sealed off.

Product thin-walled vases Designer Olgoj Chorchoj Materials borosilicate glass Country Czech Republic Date 2001

These elegant vases illustrate the complexity of components that can be formed using this method. The internal opaque white form and the transparent A tube of glass being locally heated while external tube were made separately and joined rotating on the lathe, before the wooden together later on a lathe. former is introduced.

LK016_P0114EDmakingIt2us.indd 118 16/09/2011 14:37 Thin & Hollow: Lampworking Glass Tube 119

Volumes of production Tolerances One of the best things about this type of Because this is a handworked process, semimanual process is that there is no tolerances are not very high. limit to the number of units that can be Relevant materials produced—it can be used for anything from Mainly restricted to borosilicate glass. one-offs to runs of several thousand. If you Typical products want to produce more than 1,000 units, then Anything from special laboratory apparatus it might be worth considering using a semi- and packaging, to oil and vinegar containers automated setup. (the kind you find in gourmet food stores, Unit price vs. capital investment where the vinegar bottle is trapped inside Unit price is relatively low for a product that the oil bottle), thermometers, and lighting. can be tailored and easily adapted. Capital Similar methods investment is nonexistent because there Glass blowing by hand (p.116). are no tools. Sustainability issues Speed Although glass is a natural and renewable Varies, depending on the complexity of material, its production and manufacture the shape. is less eco-friendly because of the Surface extreme heat required. However, during Excellent. lampworking the glass is shaped by Types/complexity of shape hand which, although time consuming, Limits to the shape are based on symmetry requires no machinery and therefore because of the fact that the glass tube rotates helps to balance this high use of energy. around a single axis. However, post working Additionally any glass wasted through of the glass once it is taken off the lathe breakage or error can be recycled back can allow for design details to be added. into the process to reduce material Laboratory glassware is made using this consumption and save raw materials. method, which may give you an idea of its Further information complexity. Wall sections are generally thin. www.asgs-glass.org Scale www.bssg.co.uk The scale of products is limited by the type of lathe and the skill of the craftsman.

– Highly versatile process. – Not cost-effective for large production – Shapes can be varied even within runs. the same batch. – Cost-effective for experiments and prototypes. – Complex shapes can be formed. – This type of process for making glassware is generally used to make batch-produced products without requiring any investment in tooling.

LK016_P0114EDmakingIt2us.indd 119 16/09/2011 14:37 120 Thin & Hollow: Glass Blow and Blow Molding Glass Blow and Blow Molding

There are a number of different ways in which blowing air into, or out of, a material can be used to manufacture products, many of which are described in this book. Although varieties of blow molding can be used for plastic (see, for example, injection blow molding, p.129) and even—on a limited scale—metal (see inflating metal, p.76, and superforming aluminum, p.70), it remains one of the major industrial mass-production methods for making blown glass objects. The industrial blow molding of glass today consists of two main methods: blow and blow, and press and blow (see p.124). The blow and blow method discussed here is used to make bottles with narrow necks, such as wine bottles. The term “blown glass” can, of course, also be

Product Kikkoman bottle Designer Kenji Ekuan Materials soda-lime glass Manufacturer Kikkoman Corporation Country Japan Date 1961

The proportions and narrow neck of this classic soy sauce bottle are typical of the blow and blow process for glass forming. The parting lines, which are just visible, show the point where the two halves of the mold have separated. The red plastic cap is injection molded.

LK016_P0114EDmakingIt2us.indd 120 16/09/2011 14:37 Thin & Hollow: Glass Blow and Blow Molding 121

applied to one-off handmade pieces sodium carbonate, and calcium (see glass blowing by hand, p.116), but carbonate is carried to the top level we are talking here about the sort of of the factory, where it is heated to large-scale process that is capable of 2,820°F in a furnace that can be as producing hundreds of thousands of large as a small living room. The units per day. molten glass is released in a series of To form a product using blow fat sausage shapes, known as “gobs,” and blow molding, a mixture of sand, which are drawn down by gravity into

Volumes of production Scale Range from several thousand to hundreds Because of the nature of the applications of thousands per 24-hour period. The for blow-molded products (mainly minimum production run to achieve an for domestic glass vessels), most economical price is approximately 50,000 manufacturing is set up for a maximum units. The weight of the glass, however, of 12-inch-high containers. is one of the main determinants of speed, Relevant materials and rates of 170,000 units per day are Almost any type of glass. not uncommon. Typical products Unit price vs. capital investment Narrow-necked wine and spirit bottles, This is a process for high-volume mass- and oil, vinegar, and champagne bottles. production. Tooling costs are high, and Similar methods production runs for glass need to last for While this method is suited to making days, on a continuous 24-hour cycle, for narrow-necked glass containers, press the products to be cost-effective. and blow molding can make open-necked Speed glass containers (p.124). For plastics, Depending on the bottle size, machines see injection blow molding (p.129) and can be set up to hold several molds at the extrusion blow molding (p.132). same time on a single machine. This can Sustainability issues result in very high production rates, with Although this process has an incredibly some approaching 15,000 pieces an hour. high production rate that helps to make Surface effective use of energy, the extreme heats Excellent finish—look at any wine bottle. required throughout the various stages Types/complexity of shape of production make it incredibly energy Restricted to fairly simple forms. In large- intensive. On the positive side, glass is a scale glass production, the forms need to natural and renewable material so has a be carefully designed to allow for the easy low environmental impact while it can also opening of molds—for instance, they be widely recycled. cannot have sharp corners, undercuts, or Further information large, flat areas. The blow and blow method www.vetreriebruni.com is, in fact, very inflexible, and you should www.saint-gobain-emballage.fr consult a manufacturer for specific designs. www.packaging-gateway.com Do not look at expensive perfume bottles www.glassassociation.org.uk for inspiration, because that is a different www.glasspac.com game altogether. www.beatsonclark.co.uk

LK016_P0114EDmakingIt2us.indd 121 16/09/2011 14:37 122 Thin & Hollow: Glass Blow and Blow Molding

chimney

molten glass

conveyor belt

glass “gob”

mold furnace mixed raw material 1 A mixture of sand, sodium carbonate, and calcium carbonate is fed, via a conveyor belt, into a furnace at the top of the factory. Here, it is heated to make molten glass. This molten glass is released through a series of slides, and, through gravity, falls into a fat sausage shape, called a gob. blank

air

air

mold

2 Blown down into the mold, 3 Air is injected into the neck to 4 The blank is rotated 180° and the gob is the starting point for make a partially formed blank, transferred to a second mold. the bottle. including the neck.

air air

5 More air is injected. 6 Air is injected until the glass 7 The glass bottle is lifted out is blown to form the final shape, of the mold. with the glass walls at the correct thickness.

LK016_P0114EDmakingIt2us.indd 122 16/09/2011 14:37 Thin & Hollow: Glass Blow and Blow Molding 123

the forming machines. At this stage, injected into the mold to form the final air is injected into the gob to partially shape. The various parts of the mold form the bottle, including the neck. then open and the bottle is lifted onto This semiformed glass is then removed, a conveyor belt, which carries it to rotated 180 degrees, and clamped into an annealing oven to eliminate any a further mold. At this stage, air is tension in the glass.

1 Gobs of heated glass are dropped from an 2 The glass gobs are cut to length before being elevated furnace. dropped into the mold.

3 Hot bottles leaving the mold. 4 A series of eight molding machines feed bottles onto the production line, ready for annealing.

– Very low unit price. – Versatility is very low in this high- volume method of production. – Able to make narrow- necked containers. – Very high tooling costs. – Exceptionally fast – Demands very high volumes. rates of production. – Limited to fairly simple hollow forms. – Adding color to glass can be expensive as it involves “running through” colors at the end of production to ensure that there is no bleeding between colors.

LK016_P0114EDmakingIt2us.indd 123 16/09/2011 14:37 124 Thin & Hollow: Glass Press and Blow Molding Glass Press and Blow Molding

A form of industrial glass blow production line pushes them into an molding, the technique known as annealing furnace where, over the “press and blow” is used to make period of an hour, the objects are slowly wide-mouthed containers such as jam cooled to room temperature, thus jars, rather than the narrow-necked eliminating any tension in the glass. items such as wine bottles, that are Inside the factories, machines made with the blow and blow process shoot out glowing, molten gobs of (see p.120). The main difference glass that look like shafts of light between the techniques occurs during falling into the cavities of the empty the molding process. Instead of being molds. This process has none of the blown, to create wide-mouthed vessels theater and craftsmanship of hand- the “gob” of glass is pressed onto a blown glass: the automated, greasy, male former inside the mold cavity. noisy, steaming machines can turn This can speed up production cycles out hundreds of thousands of bottles and allows greater control in the per day with just a handful of men distribution of the glass, so that a watching over this vast production. thinner wall can be achieved. After Compared with the blow and the objects have been formed, the blow process, which can produce more

Product storage jar Materials soda lime glass with thermoplastic elastomer (TPE) seal Manufacturer Vetrerie Bruni Country Italy

The open-necked shape of this jar is a typical example of a product for which you would have to consider press and blow molding in preference to blow and blow molding (see p.120).

LK016_P0124EDmakingIt2us.indd 124 09/11/2011 13:34 Thin & Hollow: Glass Press and Blow Molding 125

than 350,000 narrow-necked units per say, small pharmaceutical bottles per day, this process can churn out 400,000 day, running on a continuous 24-hour units the size of, for example, jam jars. cycle. Uninterrupted production runs When it comes to small “press and for some food packaging can last up to blow” bottles, however, the machines ten months, just producing the same can pump out up to 900,000 units of, objects over and over again.

Volumes of production of which would make releasing them from Range from several thousand to hundreds the mold difficult. Compared with blow of thousands per day. This level of high- and blow molding, press and blow allows a volume production is usually determined greater degree of control over the thickness by time, rather than by numbers of units of the glass. produced per hour. It may take up to eight Scale hours for production to be in full swing, so As with blow and blow, manufacturing a minimum production cycle is likely to be is set up for a maximum of 12-inch- around three days, with machines running high containers. without interruption. Relevant materials Unit price vs. capital investment Almost any type of glass. As with the similar process of blow and Typical products blow molding (see p.120), this is a process Open-necked jam jars and spirit bottles, only for high volume mass-production. open-necked pharmaceutical and other Tooling is prohibitively expensive unless containers, and food packaging. you have production runs of several tens Similar methods of thousands of units. For glass, blow and blow molding (p.120), Speed lampworking (p.118), and glass blowing The press and blow method is generally by hand (p.116). For plastics, plastic slightly faster than blow and blow glass blow molding (p.127) and extrusion blow production, though they have in common molding (p.132). the fact that the weight of the glass is a Sustainability issues determining factor for speed. Rates of Similar to blow and blow molding, the 250,000 units per day for a typical large extreme heats used throughout various cooking-sauce jar are fairly standard. stages of production amount to an Surface exceedingly high energy consumption. Just look at a jam jar and you can see the Yet, the exceptionally high production rate excellent finish. However, just as with blow and fast cycle times are optimized to make and blow bottles, the witness lines will economical use of this energy, while the need to be taken into account if labels are recycling of glass back into the process to be added. helps to reduce the use of raw materials. Types/complexity of shape Further information Restricted to fairly simple forms with wide, www.vetreriebruni.com open necks. In large-scale glass production www.britglass.org.uk these forms cannot have sharp corners, www.saint-gobain-conditionnement.com undercuts, or large, flat areas, all www.beatsonclark.co.uk

LK016_P0114EDmakingIt2us.indd 125 16/09/2011 14:37 126 Thin & Hollow: Glass Press and Blow Molding

“gob” of glass

mold

male mold

1 Machines shoot out molten 2 The male part of the mold 3 The soft glass is pressed “gobs” of glass, each falling begins to shape the glass as it falls. right down into the mold above an empty mold. to form a blank.

second blank mold

air

4 The blank is rotated 180 5 The blank is transferred into 6 Air is used to blow the glass degrees. a second mold. right into the mold to form the final shape.

– Very low unit price. – Very high tooling costs. – Suited to making – Limited to fairly simple hollow thin-walled, open- forms. necked vessels. – Adding color to glass can be – Exceptionally fast expensive, as can running through rates of production. colors at the end of production to clean out the machines. – Exceptionally fast cycle times. – Demands high volumes in order to be economical.

LK016_P0114EDmakingIt2us.indd 126 16/09/2011 14:37 Thin & Hollow: Plastic Blow Molding 127 Plastic Blow Molding

Blow molding is an umbrella term molding (see p.132). All have differing that describes one of the major potential to create shapes, but, in industrial mass-production methods simple terms, all of them involve a for producing a whole host of hollow process that is like blowing a balloon products. In one sense it is unusual, into a mold to form a shape. The because it is a process that can be used process starts with a pre-form being for molding plastic containers as well fed into a two-part mold. The closing as glass bottles (see glass blow and of the mold snips the material to an blow [p.120] and glass press and blow appropriate length, forming a seal at [p.124] molding). one end of the plastic. This pipelike There are several forms of form is fed into a second mold where blow molding suitable for plastics, air is blown into it, forcing the plastic including injection blow molding and to expand against the mold cavity to injection stretch molding (see p.129), form the final shape, after which the and extrusion and co-extrusion blow mold opens and the part is released.

two-part mold

air

pre-form

1 A pipelike “pre-form” 2 The mold closes, 3 Air is blown into the 4 The mold opens and is fed into a two-part snipping the material to pre-form, forcing the the part is released. mold. an appropriate length plastic to expand against and forming a seal at the mold cavity to form one end of the plastic. the final shape.

LK016_P0114EDmakingIt2us.indd 127 16/09/2011 14:37 128 Thin & Hollow: Plastic Blow Molding

Volumes of production Relevant materials Depending on the size and the material, The typically waxy, high-density blow molding can be an extremely rapid polyethylene (HDPE) is one of the most form of production, with an output of from common materials used for this process. approximately 500 units per hour to more Other materials include polypropylene, than a million units per 24-hour cycle. To polyethylene, polyethylene terephthalate get the most out of the process, in terms of (PET), and (PVC). cost savings, production should run into the Typical products hundreds of thousands. The chances are that in the average Unit price vs. capital investment household you will have at least one large Unit prices for most standard blow- cabinet full of different plastic containers molded parts are very low, which is best that are blow molded. Basically, blow- comprehended by looking at the volume molded items include everything from of cheap products and packaging that is plastic milk cartons and shampoo bottles produced with this process. This economy to toys, toothpaste tubes, detergent of scale is counterbalanced, of course, bottles, watering cans, and—outside the by the extremely high tooling costs. home—car fuel tanks. Speed Similar methods Small containers can be produced in Stretch molding, extrusion blow molding multicavity molds to yield approximately (p.132), injection blow molding, and 60,000 small (less than, say, 23 fluid ounces) co-extrusion blow molding (p.132). polyethylene terephthalate (PET) bottles Sustainability Issues per hour. A highly automated process that as a Surface result of very fast cycle times maximizes Excellent finish, but parting lines remain the use of heat and electrical energy down the length. to produce a very precise quantity of Types/complexity of shape material and optimized use of energy. Depending on the specific process, blow- PET, which is one of the main materials for molded shapes are generally simple blow molding, is among the most widely and rounded. Although products can recycled plastics. be produced with no draft angles, Further information manufacturers prefer a small draft. www.rpc-group.com Scale www.bpf.co.uk From small cosmetics bottles to parts that weigh more than 55 pounds.

– Very low unit price. – High tooling costs. – Exceptionally fast rates of – Demands high production. volumes in order to be cost-effective. – Details, such as threads, can be molded in. – Limited to fairly simple hollow forms.

LK016_P0128EDmakingIt2us.indd 128 16/09/2011 16:46 Thin & Hollow: Injection Blow Molding 129 Injection Blow Molding with injection stretch molding

Injection blow molding is most easily placed into the mold cavity where it described as being a subdivision of is blown with air, forcing the plastic plastic blow molding (see p.127), against the mold cavity. the process that works on the same Using an injection-molded principle as blowing up a balloon, but pre-form means that this method into a mold that forms the shape. offers a greater degree of stability and As the name implies, this is a control over the shape than extrusion two-step molding process that offers blow molding (see p.132), although the a number of advantages over other choice of suitable materials is forms of blow molding because it is more limited. possible to create far more complex Injection stretch molding shapes around the neck of the molded is a method used for high-end part. A hollow pre-form is made using products (such as bottles) made from injection molding (see p.196), which polyethylene terephthalate (PET) allows for the molding of a complex which uses a rod to stretch a pre-form thread at the neck. The pre-form is into the mold before blowing.

air

pre-form

1 An injection-molded pre-form 2 Compressed air is injected, 3 The mold opens and the part is placed in the mold. blowing the pre-form into is released. the mold cavity to form the final shape.

LK016_P0114EDmakingIt2us.indd 129 16/09/2011 14:37 130 Thin & Hollow: Injection Blow Molding

Product injection-molded pre-form (left) and blow-molded bottle (right) Materials polyethylene terephthalate (PET) Country Germany

This pre-form and the resulting blown bottle show, in very simple terms, how straightforward the process is that forms the billions of plastic bottles that litter our urban landscape. The advantage of using injection molding is demonstrated by the detailed thread that has been formed around the neck of the pre-form.

Product Sparkling Chair Designer Marcel Wanders Materials polyethylene terephthalate (PET) Manufacturer Magis Country Italy Date 2010

The Sparkling Chair is a great illustration of how a material and production method can be translated from packaging into a completely new area of furniture.

LK016_P0114EDmakingIt2us.indd 130 16/09/2011 14:37 Thin & Hollow: Injection Blow Molding 131

Volumes of production Relevant materials Injection blow molding is ideally suited to Compared with extrusion blow molding high-volume production, which often runs (see p.132), this method is suited to more into millions of units. rigid materials such as (PC) Unit price vs. capital investment and polyethylene terephthalate (PET). Costly tooling, for both the injecting and It is, however, often used for nonrigid blowing parts of the process, as well as materials, such as polyethylene (PE). substantial setup charges. However, unit Typical products prices can be extremely low because of the Small shampoo, detergent, and volumes produced, and this justifies the other bottles. high initial costs. Similar methods Speed Extrusion blow molding (p.132) for The various forms of blow molding are plastic, and press and blow molding difficult to pin down in terms of speed of (p.124) for glass. production due to variables such as part Sustainability issues size and the number of mold cavities in As opposed to other forms of plastic blow operation. A typical 5-fluid-ounce bottle, molding, the pre-form is heated twice: first however, can be produced by injection blow during production of the pre-form and then molding in an eight-cavity mold at the rate when it is blown into the final product, of 2,400 units per hour. thus doubling on energy use. Virtually no Surface waste is created during injection blow Excellent finish. molding and cycle times are very fast with Types/complexity of shape optimized use of material and energy. The Injection blow molding is suited to fairly process is often used to produce disposable simple shapes, which have a large radius PET packaging; as one of the most widely and consistent wall thicknesses over the recycled plastics PET can be reprocessed whole product. to avoid landfill. Scale Further information Typically used for containers of less than www.rpc-group.com 8 fluid ounces. www.bpf.co.uk

– Very low unit price. – Higher tooling costs than in extrusion – Exceptionally fast rates of blow molding production. (see p.132). – Suited to small containers. – Demands high – Allows greater control over neck volumes. design, weight, and wall thickness – Limited to fairly than other blow-molding methods. simple hollow forms.

LK016_P0114EDmakingIt2us.indd 131 16/09/2011 14:37 132 Thin & Hollow: Extrusion Blow Molding Extrusion Blow Molding with co-extrusion blow molding

Extrusion blow molding is part of to form the final shape. The process the plastic blow molding group of leaves excess “pinched” material processes (see p.127). In this particular (a “tail”), which must be removed— method, the plastic is extruded (see though evidence of it can be seen in the extrusion, p.96) into a sausage shape finished product, on the underside of known as a “lug” and pinched into any shampoo bottle, for example. short lengths as it drops into the mold In co-extrusion blow molding cavity. Here, it is blown with air, forcing different materials are combined to the plastic against the mold cavity form a multilayered product.

raw material heater element

molten plastic

die electric screw motor hot knife 1 Raw pellets are fed from a hopper into a heated cylinder, where a screw pushes the now molten plastic through a die, forming a lug “lug” (similar to toothpaste coming out of the tube). This lug is snipped to an appropriate mold length as it drops into the mold.

air hose

next mold

2 The mold is moved away from the die 3 On cooling, the component is ejected from and air is injected, inflating the material and the mold. It may now require finishing to pushing it against the walls of the mold. remove the “tail.”

LK016_P0114EDmakingIt2us.indd 132 16/09/2011 14:37 Thin & Hollow: Extrusion Blow Molding 133

Volumes of production for small runs and can be used to make Unlike injection blow molding (see p.129), products at the larger end of the blow- which offers the possibility of production molding scale, typically more than about runs extending into the millions, extrusion 20 fluid ounces. blow molding can be used on much shorter Relevant materials runs, sometimes as low as 20,000. Polypropelene (PP), polyethylene (PE), Unit price vs. capital investment polyethylene terephthalate (PET), and Although lower in cost than injection blow polyvinyl chloride (PVC). molding (by about a third), it is still an Typical products expensive setup. Extrusion blow molding is best suited Speed to larger products, which might typically As with other, similar methods, the include toys, oil drums and car fuel tanks, production rate is determined by the weight and large detergent bottles. of the part: a typical gallon container can be Similar methods produced at a rate of 1,000 per hour (using Injection blow molding (p.129) and a single machine, with four molds running rotational molding (p.137). concurrently). Blow-molded milk bottles of Sustainability issues the sort found in supermarkets can be made A small amount of excess plastic produced at a rate of around 2,000 units per hour. from runners where the molten plastic Surface was fed in is trimmed from each mold. This Excellent finish. waste can be heated into a molten state Types/complexity of shape again and recycled back into the process Extrusion blow molding is suited to the to reduce material consumption and production of larger and more complex prevent waste. Additionally, at the shapes than injection blow molding, end of the product’s lifespan the plastic notably the integrated handles on plastic can be recycled to reduce the use of raw milk containers, or on the large fuel and non-renewable materials. containers you can find at gas stations. Further information Scale www.rpc-group.com Although it is capable of producing www.bpf.co.uk products such as shampoo bottles, www.weltonhurst.co.uk extrusion blow molding is also suitable

– Very low unit price. – Demands high volumes. – Fast rates of production. – Suited to large containers of more than 20 fluid ounces. – Compared with injection blow molding (see p.129), extrusion blow molding is capable of producing more complex shapes. – Lower tooling costs than for injection blow molding.

LK016_P0133EDmakingIt2us.indd 133 16/09/2011 16:46 134 Thin & Hollow: Dip Molding Dip Molding

Dipping a shape into a material that has been melted (or is in an otherwise liquid state) is possibly one of the oldest methods of forming shapes. It is also one of the simplest techniques to understand, and, in terms of tools and molds, it is one of the cheapest methods of producing plastic products. To be presented with a ceramic former, such as the one illustrated here, is to be given a gem from the usually hidden world of manufacturing. Artists (particularly Rachel Whiteread in her award-winning 1993 concrete House) have often explored the negative spaces within our environments. In a similar way, these little gems give us a unique view into the world of production from an angle that is rarely seen. The bulbous shape triggers a small flash of recognition,

Product balloon former (far left) and balloon (left) Designer Michael Faraday created the first rubber balloon in 1824 Materials ceramic former; latex balloon Manufacturer Wade Ceramics Limited (balloon former)

The simple ceramic former perfectly illustrates the principle behind dip molding, showing how hollow products—such as this party balloon—are made.

LK016_P0114EDmakingIt2us.indd 134 16/09/2011 14:37 Thin & Hollow: Dip Molding 135

but you cannot quite put your finger a former into a liquid polymer bath, on what it is until someone tells you let it cure, and peel it off. In reality, it that the shapes are ceramic formers is a little bit more complex than that, for making balloons. because dip molding is a process In principle, the process of dip that can be adapted to many different molding is incredibly straightforward. materials and setups, although the As the name suggests, you simply dip basic idea stays the same.

An automated production line showing the dipping of A vat of sky-blue latex being used to produce ceramic formers to make rubber gloves. party balloons.

– Highly cost-effective for short – Limited to simple production runs. shapes. – A prototype former and sample moldings can be produced in a matter of days.

LK016_P0114EDmakingIt2us.indd 135 16/09/2011 14:37 136 Thin & Hollow: Dip Molding

Volumes of production Tolerances From batch production to high-volume Dip molding does not achieve a high mass-production. level of accuracy, apart from on the Unit price vs. capital investment internal dimensions. One of the least expensive ways of mass- Relevant materials producing plastic components, with Because of the nature of the process, which reasonably cheap tooling and easy-to- involves the former being “undressed” produce samples, while still allowing for as the part is removed, it is limited to soft cost-effective unit parts. materials and parts that can be stretched Speed over the molds, including PVC, latex, This process involves many steps, including polyurethanes, elastomers, and silicones. preheating of the former, dipping, curing, Typical products and finally peeling the finished molding A whole range of flexible and semirigid from the former, which makes for a slow products, from kitchen and surgical gloves process if performed manually. Complex to balloons and those soft, waxy plastic moldings may take up to 45 minutes to handlebar grips for children’s bikes. complete, while the production of very Similar methods simple shapes, such as end caps (for An economical alternative to plastic blow example, simple bicycle-handlebar grips) molding (p.127) and rotational molding can be fully automated and may take only (p.137). 30 seconds. Sustainability issues Surface Heat is required to keep the polymer The exterior of the component is determined bath in its molten state throughout by the natural state of the material, and processing so dip molding is energy may have a small nipple as evidence of the intensive. Furthermore, some plastics polymer dripping from the mold. such as latex and silicone are often not Types/complexity of shape widely recyclable. On a brighter note, latex Soft, rubbery, flexible, though simple, forms. products such as balloons can, in fact, Products must be shaped in such a way be composted, which prevents the that they can be unpeeled from the mold. material entering the waste stream. Scale Further information The scale of dip moldings is theoretically www.wjc.co.uk only limited by the size of the bath www.uptechnology.com containing the polymer, but generally www.wade.co.uk 1 moldings range from /25-inch-diameter end www.qualatex.com caps to 24-inch industrial pipe covers.

LK016_P0136EDmakingIt2us.indd 136 16/09/2011 16:47 Thin & Hollow: Rotational Molding 137 Rotational Molding AKA Roto Molding and Rotational Casting

Rotational molding is all about making things that are hollow. If you have ever wanted to know how chocolate Easter eggs are made, then the answer lies in this method of production. One of the interesting things about rotational molding is that the soft and rounded products that are typical of this method very much take their aesthetic from the limitations of the process. This is quite unlike injection molding (see p.196), which uses pressure to inject material into the mold, producing sharp edges and fine detail. Roto molding, as it is sometimes known, uses only heat and the rotation of a mold to form parts and thus lacks the fineness of pressure-formed parts. In a sense, rotational molding is based on a similar idea to ceramic slip casting (see p.140). In both methods, a liquid material is built up on the internal cavity of a mold, allowing the manufacture of hollow parts. It is a simple, four-stage process, which begins with adding powdered polymer Product Rotationalmoldedshoe to a cold die. The amount of powder Designer Marloes ten Bhömer in relation to the size of the die Materials rubber and stainless steel determines the wall thickness of the Manufacturer Marloes ten Bhömer final component. The second stage Country UK involves the die being uniformly heated Date 2009 inside an oven, while simultaneously The shoes demonstrate a production process being transferred into a completely new type of product. The image above shows how the two parts are separated (not actually with a knife) and rejoined to make the shoe.

LK016_P0114EDmakingIt2us.indd 137 16/09/2011 14:37 138 Thin & Hollow: Rotational Molding

being slowly rotated around two axes. This allows the polymer (which is now liquid) to tumble around the inside of the die, where it builds up on the walls and creates a hollow form. Finally, while the die is still rotating, it is cooled using air or water before the component is removed.

– Ideal for hollow shapes. – Suitable for low- volume production. – Simple process. – Allows for cost- effective production of large components.

– Not suitable for making small, precise components. These images show (top) close-up of half of the rotational molding tool; (middle and above) tabletop rotational molding.

LK016_P0114EDmakingIt2us.indd 138 16/09/2011 14:37 Thin & Hollow: Rotational Molding 139

Volumes of production Tolerances From batch production to high-volume Compared with other plastic molding mass-production. methods, tolerances are low due to Unit price vs. capital investment shrinkage, cooling rates, and the wall Less expensive to set up and operate than thickness, which varies slightly across injection molding (see p.196). Because the molding. there is no pressure involved, molds are Relevant materials simpler and cheaper. Unit costs are still Polyethylene, which has that Edam- very low. cheesy feel, is a common material for Speed rotational molding. Other resins can This is affected by the size of the component also be used, including acrylonitrile and the wall thickness, both of which affect butadiene styrene (ABS), polycarbonate, the cooling-cycle time. Some components, nylon, polypropylene, and polystyrene. such as plastic drums for storing liquids, Reinforcement fibers can also be may require entry and exit holes for the introduced to increase strength in liquid to be cut by hand. the final component. Surface Typical products The internal surface may reveal the swirls Chocolate eggs, plastic road-traffic cones, of the plastic as it was being formed, similar portable toilets, tool cases, large toys that to the swirls of chocolate you can see on take up half your living room, as well as the inside of an Easter egg. The surface many other hollow products. that is in contact with the mold is of much Similar methods higher quality. While it may not be possible Centrifugal casting (p.161) is a similar to achieve a super-glossy finish, matte process for plastics, but it is not widely finishes can be built into the mold to hide available and can only produce small small defects. Inserts with graphics on can parts. Also blow molding in all its forms also be molded into parts. (pp.120–33), and dip molding (p.134). Types/complexity of shape Sustainability issues Adaptable to a range of shapes. Even As with most plastic processing, high undercuts are possible. Wall thickness temperatures are needed to melt the should be kept uniform, between plastic, which makes the process quite 1 5 approximately /12 and /8 inch. Unlike with energy intensive. However, this is a other processes, there can be a buildup of pressureless process. It is difficult to material in corners which makes them the control the precise wall thickness and strongest part of the component. therefore the amount of material that is Scale needed. Any faulty moldings produced Starting with chocolate eggs, it is possible can be melted down and reused in the to manufacture hollow products up to 23 process too. feet long by 13 feet wide, such as panels for Further information construction workers’ temporary huts. www.bpf.co.uk www.rotomolding.org

LK016_P0114EDmakingIt2us.indd 139 16/09/2011 14:37 140 Thin & Hollow: Slip Casting Slip Casting

This is a manufacturing process Product Wedgwood ® teapot, that is just as likely to be used in before finishing a college art and design program Materials bone china Manufacturer Wedgwood as in the industrial workshops of Country UK Wedgwood® or Royal Doulton. In slip casting, ceramic particles are first It is often the unfinished article that best reveals the production process, rather than the finished suspended in water to form “slip,” product. This image was taken while the clay was which is something like the color still wet, before the excess material at the top was and consistency of melted chocolate. trimmed off. The parting lines, where the two halves of the mold met, are still visible on the sides of This slip is tipped into a plaster mold. the teapot. Because the dry plaster mold is porous, the liquid is absorbed from the outer layers of the slip, leaving a coating of leathery and hard ceramic

LK016_P0114EDmakingIt2us.indd 140 16/09/2011 14:37 Thin & Hollow: Slip Casting 141

on the inner surface of the mold. When clean edge before the mold is opened a sufficient thickness has built up, the and the molding, now in its “green” mold is turned upside down and the state, is removed, ready for firing. remaining muddy liquid is poured out. Pressure-assisted slip casting The excess ceramic around the opening (see p.234) is a process that is of the mold is trimmed to produce a employed for larger components.

Volumes of production also a need for a kiln that is large enough Versatile production volumes—anything to fire the finished product. Products such from small-scale craft batch production to as tableware represent the average size. factory production. Tolerances Unit price vs. capital investment It is hard to achieve high tolerances Slip casting is economical for small because the parts shrink considerably quantities because inexpensive molds during firing and, even before that, inside can be made in small workshops while the mold as the water is being drawn maintaining fairly low unit prices. However, out of the slip. in industrial production the plaster molds Relevant materials have a limited life and need to be replaced All types of ceramic. after approximately 100 . Typical products Speed Slip casting is used to make any type of Slip casting can be summarized by saying hollow product, from one-off pieces of that “time equals thickness.” Because of tableware such as teapots, vases, and the number of operations and drying times figurines to high volumes of sanitary ware. involved, even as an industrial process slip Similar methods casting still has one foot in the craft tradition, Pressure-assisted slip casting (p.234) and with a fair degree of labor involved. tape casting (a process used for making Surface multilayered for the electronics Slip casting is a great process for achieving industry, involving laying down thin sheets surface patterns on objects (such as raised of ceramic-loaded polymers that flower patterns). As with all ceramic are laminated with other materials). products, glazing is required. Sustainability issues Types/complexity of shape The excess slip collected during molding Shapes can range from small and simple to and after trimming is recycled back large and complex, and can include parts into the process to reduce material with undercuts. Anything from bathroom consumption and minimize the use of products to art objects and dinnerware can raw resources. The process is largely be made with this process. labor-assisted, which reduces the Scale use of power and helps to balance out Large molds can become very heavy and, high energy consumption during given the massive amount of slip that the firing stage. would be needed to fill the void, slip casting Further information may not be suited to large shapes. There is www.ceramfed.co.uk www.cerameunie.net

LK016_P0114EDmakingIt2us.indd 141 16/09/2011 14:37 142 Thin & Hollow: Slip Casting

slip plaster mold

1 Slip is poured into 2 The slip is allowed to 3 The mold is turned 4 The excess ceramic a plaster mold, which sit in the mold until a upside down and any around the opening of absorbs the water, sufficient thickness has remaining muddy liquid the mold is trimmed leaving a layer of hard, built up. is poured out. to produce a clean edge leathery ceramic. before the product is released for firing.

1 Empty plaster molds. 2 Molds filled with slip.

– Ideal for producing hollow ware. – Labor-intensive. – Complex forms can easily be – Limited control over achieved. tolerances. – Efficient use of material. – Slow production rate. – Lends itself well to low-production – Large-scale runs. production requires many molds, which themselves require storage.

LK016_P0114EDmakingIt2us.indd 142 16/09/2011 14:37 Thin & Hollow: Hydroforming Metal 143 Hydroforming Metal AKA Fluid Forming

Hydroforming is a fairly new process for exists for forming pillow shapes from forming steel and other metals. It works two panels sealed together. by forcing a water and oil solution into A number of benefits have a cylinder, or other closed shape, that resulted from this process, including is confined by a die. In essence, the parts with reduced weight and faster process makes it possible to “inflate” production times than with similar metal tubes and form metal sheets methods, such as superforming into elaborate shapes by forcing them aluminum (see p.70) and inflating against a die. The water pressure of metal (see p.76). In order for the up to 15,000 psi expands the material, full potential of hydroforming to be forcing it to conform to the shape of the exploited, designers need to think die to form the required component. of it as a way of reducing costs by Tubes and cylinders are the making something from a single most common starting points for material rather than having to produce hydroforming, although panel a multitude of parts that need to be hydroforming at high pressures also joined together.

Product T-section of a concept for a handrail system Designers Amelie Bunte, Anette Ströh, André Saloga, and Robert Franzheld, students at the Bauhaus University in Weimar; engineering by Kristof Zientz and Karsten Naunheim, students at Darmstadt University of Technology Materials hydroformed powder-coated steel; stainless steel tubes Manufacturer college project Country Germany Date 2005

This deceptively simple, white-powder-coated steel junction from a student project for handrail systems illustrates the ability of hydroforming to create a complex form that changes from one diameter to another through a complex curve. This could otherwise only be made using conventional forming techniques that would then need to be welded together.

LK016_P0114EDmakingIt2us.indd 143 16/09/2011 14:37 144 Thin & Hollow: Hydroforming Metal

1 An example of the tooling and the die cavity 2 Semifinished hydroformed components. into which the metal is placed.

die water and oil

metal tube

plug

1 In tube forming, the metal tube is 2 A water and oil solution is used to fill the tube and inserted into a two-part die and sealed a pressure of up to 15,000 psi is applied by inserting at either end, with only one opening that plugs at either end of the tube, forcing the water to allows the liquid to be fed in. “fill out” the tube until it conforms to the die cavity.

3 The solution is emptied from the filled- 4 The final, hollow part is removed. out tube.

LK016_P0114EDmakingIt2us.indd 144 16/09/2011 14:37 Thin & Hollow: Hydroforming Metal 145

Volumes of production difficult to manage pieces that were much High production volumes. larger than this. Unit price vs. capital investment Tolerances Considerable investment in tooling Because of the die, the process allows the required, but being able to produce part to be controlled during forming to components as single parts, rather than as prevent wrinkling or tearing. multiple parts joined together, should help Relevant materials to reduce the price per unit. Any metal with reasonably elastic Speed properties that can take the high levels In a highly automated factory setting, it is of tension involved, including high-grade possible to achieve production cycle times steel and heat-treatable aluminum. of 20–30 seconds for a small part, even in a Typical products workflow setup where parts are positioned Bicycle frames, bellows, T-sections, and and connected inside the die. a variety of structural automobile Surface components, including floor pans, In general, hydroforming does not have van body sides, and roof panels. much of an effect on the surfaces of Similar methods materials. It does, however, leave small Inflating metal (p.76) and superforming scratches and marks at the ends of a work aluminum (p.70). piece from the clamps that seal the ends, Sustainability issues but these are normally trimmed off. The hydroforming technique can allow Types/complexity of shape for thinner-walled parts and eliminate Tubular materials can be made to bulge the need for complex joins, which can into quite elaborate forms. Examples of this substantially reduce material consumption include T-sections, which would otherwise and weight without compromising need to be made by joining multiple strength and rigidity. As the metal flows components. instead of stretching during forming, Scale it is less likely to work-harden, which The bigger the part, the more pressure is eliminates the need for further processing needed for forming, which in turn requires such as annealing, which would require a heavier mold to contain the powerful additional resources and energy. forces involved in this process. Some large Further information car parts, including hoods, can be made www.hydroforming.net with hydroforming, although it would be http://salzgitter.westsachsen.de

– Strong, often complex, single – High tooling components due to the elimination investment needed. of joints. – Limited number of – Potential for parts with lower companies offering weight but with high strength. the process. – Ability to reduce multiple components and joins into one complex part.

LK016_P0145EDmakingIt2us.indd 145 16/09/2011 16:49 146 Thin & Hollow: Backward Impact Extrusion Backward Impact Extrusion AKA Indirect Extrusion

Impact extrusion is a cold process for forming metals that marries forging (see p.187) with extrusion (see p.96). In a nutshell, backward impact extrusion is a method of forming hollow metal parts by striking a metal billet (or disk), which is confined within a cylindrical or square die, so hard that the metal is forced upward into the space between the “” (or punch) and the die. The gap between the punch and the inside of the die determines the wall thickness of the final component. There are in fact two types of impact extrusion, forward extrusion and backward extrusion. Backward (or indirect) extrusion is used to make hollow shapes, because the punch is solid and thrusts the material around itself into the space between itself and the die.

Product Sigg drinks bottle Materials aluminum Manufacturer Sigg Country Switzerland Date range brought to market 1998

This cutaway of the famous Sigg container shows the thin walls and the typical shapes that are a feature of impact extrusion.

LK016_P0114EDmakingIt2us.indd 146 16/09/2011 14:37 Thin & Hollow: Backward Impact Extrusion 147

The other sort of impact single operation, where the repeated extrusion, forward (or direct) extrusion, action of the punch pushes material can only produce solid sections. In this both upward (in order to form a hollow instance the space between the punch top) and downward (to make a solid, and the die is too small to allow metal to shaped base). wrap itself around the punch. Instead, Designs that require outward the metal is hammered downward tapering may need some post forming into a die forming a straightforward after extrusion, and any threaded solid shape. Nevertheless, these sections, such as the bottle neck, are processes can also be combined in a also added after forming.

1 The aluminum billet, 2 The cylinder created by 3 Tapering is added by a 4 With the threading at which is placed on the die. the action of the punch secondary process. the neck added, this is using backward extrusion. now recognizable as a Sigg bottle.

– Produces cost- – The final component is limited in effective shells in length to the length of the punch a variety of square needed to strike the billet. and cylindrical cross- sectional shapes. – Only suited to parts where the length of the part is greater than – Removes the issue of four times the diameter. joints by producing components with a – Post forming is required to add uniform, seamless tapers or threads. wall. – Subject to the limitations of the die. – Inexpensive tooling compared with other high-volume processes.

LK016_P0114EDmakingIt2us.indd 147 16/09/2011 14:37 148 Thin & Hollow: Backward Impact Extrusion

punch

die 1 An aluminum billet is 2 The die is punched placed in the die. with the impact forcing the material upward into aluminum the space between the billet “hammer” and the cylinder.

Volumes of production Tolerances Impact extrusion is a high-volume High degrees of tolerance achievable by production method. Depending on the size backward impact extrusion. (Obviously, of the component, minimum quantities forward impact extrusion offers greater range from 3,000 upward. tolerances because the final object is solid.) Unit price vs. capital investment Relevant materials Surprisingly, tooling is not as expensive as Aluminum, magnesium, zinc, lead, copper, you might expect for a process that is used and low-alloy steels. for high volumes, but the speed with which Typical products it turns out products means that it requires Backward extrusion is a popular method a large minimum order. Unit costs are for forming drinks and food cans, aerosol very low. cans, and similar containers. Forward and Speed backward extrusion are used together to The famous 1-liter (34 oz) Sigg bottles make such items as ratchet heads. (pictured) are made at a rate of 28 per minute. Similar methods Surface Forging (p.187) and extrusion (p.96). Offers a reasonably high degree of surface Sustainability issues finish. Backward impact extrusion gives the Types/complexity of shape metal improved strength and rigidity It is possible to produce thin- or thick- after forming, to allow for thinner wall walled containers using backward impact thicknesses which can help to minimize extrusion, either cylindrical or square, that material use. It is a cold-working process are closed at one end. (The forward process that requires only one single impact produces solid sections from solid rods of to form the metal into shape so energy different shapes and sizes.) Both methods consumption is fairly low for a process with are best suited to symmetrical shapes. There such a fast cycle rate. In terms of material are also certain guidelines regarding the use, it is worth noting that aluminum is ideal proportion of length and width, but widely recycled. you should consult your manufacturer, as Further information these will depend on the material being used. www.mpma.org.uk Scale www.sigg.ch Suitable for parts weighing from a fraction www.aluminium.org of an ounce up to approximately 2 pounds.

LK016_P0114EDmakingIt2us.indd 148 16/09/2011 14:37 Thin & Hollow: Molding Paper Pulp 149 Molding Paper Pulp including rough pulp molding and thermoforming

Paper is one of the most efficiently The manufacture of molded collected and recycled materials of the paper products is based on two methods: modern age. Much of what is collected the conventional rough (or industrial) is converted into pulp to make new pulp process and a thermoforming products for a variety of industries, process. Both methods begin by though these are usually simple soaking the collected paper in water sheets or packaging. However, it is the molding of paper pulp using highly unusual mass-production technology that makes it particularly noteworthy.

Product disposable urine bottle Materials paper pulp Manufacturer Vernacare

The mesh texture, which is subtly visible on this image, is a testament to how the water was squeezed out through a wire mesh to compact the paper pulp into a finished product. The parting lines on the mold are also visible, and the text on the product shows how the process can achieve a decent standard of surface embossing.

LK016_P0114EDmakingIt2us.indd 149 16/09/2011 14:37 150 Thin & Hollow: Molding Paper Pulp

in a giant tank, with the proportions impression that you can see on, for of paper and water based on the level example, a standard egg box. A male of consistency needed to achieve the mold is then used to compress the particular end product (typically, the pulp, and a vacuum draws the water amount of paper can be as low as 1 out of the mold, sucking the fibers percent). The resulting gray mixture firmly into the mold. At this point the is churned with a blade to produce the whole thing is dried, thus forming the molding compound of “paper mush.” final product. Unlike most other material As well as using heat, as its name molding methods, which involve the suggests, the thermoforming process mold being stationary, the aluminum involves the use of transfers and or plastic female molds used in presses. After molding, the component molding paper pulp (which have is picked up by a transfer, which is the draining holes all over them) are negative shape of the component, and submerged in tanks of liquid paper carried to a heated press that forms the pulp. The molds are covered with final shape. It offers several advantages, mesh or gauze, which allows the water including better quality surface finish to drain out, hence the typical mesh but is more costly to set up.

– Uses recycled and recyclable – Requires large material. production volumes. – Produces lightweight parts. – Only suitable for use with a limited range of materials.

LK016_P0114EDmakingIt2us.indd 150 16/09/2011 14:37 Thin & Hollow: Molding Paper Pulp 151

Volumes of production Tolerances Due to the high cost of tooling and the Tolerances vary depending on the specific 1 1 speed at which parts can be made, both process. Tolerances of ± /50– /25 inch are rough pulp molding and thermoforming achievable using the thermoforming require high volumes of production. method. For the rough pulp process, 1 1 Minimum runs of two days (about 50,000 ± /12– /8 inch is achievable. pieces) are generally required. Relevant materials Unit price vs. capital investment The raw materials come from two main Tooling costs and setup times are high. sources: newsprint and cardboard. The The two methods have different tooling choice of material depends on the final requirements; the thermoforming method product and the strength that is required. costs approximately twice as much as the For strong packaging that needs to satisfy raw method. drop-test requirements (used, for example, Speed for cell phones, PDAs, and cameras), the Thickness, and the amount of paper that long fibers found in cardboard provide the needs to be dried, determine the speed. best solution. As a guide, the molded inserts for four Typical products cell-phone boxes take about a minute Conventional rough pulp is used to make to produce. This is based on a multiple wine packs and industrial packaging. The impression, meaning four components thermoforming process is used to produce are molded at the same time. These four more sophisticated products such as cell- different molds can therefore produce phone packaging. 960 units per hour. Similar methods Surface None. Just think of a paper egg carton to get a Sustainability issues sense of that uniquely soft, warm, cookie- Pulp is made from recycled paper products like surface. The rough pulp process so the process helps to reduce waste produces one rough side, picking up an and the use of raw materials in the first impression from the wire mesh, and a instance, while the pulp is recyclable smooth surface created by the polished at the end of its use. The conventional aluminum, or plastic, face of the mold. rough forming of the material requires Types/complexity of shape little energy whereas the thermoforming Some fairly complex patterns can be process involves heat, which significantly molded, but large draw angles need to increases energy consumption. The main be allowed for; forget any complex three- drawback is the amount of water the dimensional detailing. processes require. Scale Further information Standard production allows for up to www.huhtamaki.com 60 by 16-inch areas—however, some www.mouldedpaper.com manufacturers can sustain sizes up to www.paperpulpsolutions.co.uk 8 feet long. www.vaccari.co.uk www.vernacare.co.uk

LK016_P0151EDmakingIt2us.indd 151 16/09/2011 16:50 152 Thin & Hollow: Contact Molding Contact Molding including hand lay-up and spray lay-up molding, vacuum-bag and pressure-bag forming

Contact molding is a method of by spraying, before rollers are used to forming composites by taking plastic squash and to distribute the mixture reinforcement fibers, layering them, evenly in the mold. The spray-up then applying liquid resin over the top method is used when larger areas are to create a hard shell. In its simplest involved, using short, chopped fibers form—the traditional hand lay-up that are incorporated into the resin method—the reinforcements are laid before spraying. In both cases, the over a mold before the liquid resin thickness of the part is controlled by is brushed or sprayed into it. If you the number of layers that are applied. have ever repaired a dent or hole in Vacuum-bag and pressure-bag an old car or boat you will probably forming are variations of the hand have used a simple version of this lay-up and spray lay-up methods for process. In industry, it is a process for forming composites, but they give producing large-scale moldings in the molding finer detail and greater composite materials, and it is one of the strength. The procedure is similar most frequent methods of combining for both variants: in the pressure- various types of reinforcement fiber bag method, once the materials have with thermoset resins. been laid over the mold, a flexible bag The open-form molds used made of rubber is placed over them in hand lay-up can be made from and subjected to pressure by clamping any material, but wood, plastic, or it, which compacts the materials, cement are the most common. The squeezing the resin and reinforcement reinforcement fibers are generally together; with the vacuum-bag method, glass or carbon, but other materials, the part is cured inside a bag from including natural fibers, can be used. which the air has been sucked out, A resin is then applied with a brush or forcing the materials together.

– The use of reinforcing fibers – Quite a labor-intensive results in high strength. process. – Other performance – Requires good ventilation additives, such as flame- due to the resins. retardants, can easily be incorporated. – Other composite-forming methods (such as filament – Versatile in terms of shape winding, see p.140) offer and size. much higher density and strength-to-weight ratios. – Allows thick sections to be produced.

LK016_P0114EDmakingIt2us.indd 152 16/09/2011 14:37 Thin & Hollow: Contact Molding 153

With vacuum-bag forming it is lay-up methods, both vacuum-bag and possible to achieve similar results to pressure-bag forming result in higher those that you find with autoclave fiber content and density because of molding (see p.156) but without the use of a vacuum or pressure, which the need for a pressure chamber. also limits the amount of potentially Compared with the hand and spray harmful vapor to a minimum.

Volumes of production Relevant materials The process in all these methods is always Reinforcement materials include advanced slow due to the labor involved. However, fibers such as carbon, aramid, and glass, the nature of the spray-up method makes it and natural materials such as jute and faster than the hand lay-up process. cotton. Polyester is the most widely Unit price vs. capital investment used thermosetting resin; others include Tooling can be inexpensive but the time epoxy, phenolic resin, and silicone. taken to form parts makes them expensive Thermoplastics are far less cost-effective. to mass-produce as a high-volume process. Typical products Speed General glass-reinforced plastic (GRP) Depends on the type of hand lay-up items such as boat hulls, car panels, technique and the size of the molding. furniture, bathtubs, shower pans, and Spray lay-up is faster, but larger areas mean cheap seats on the decks of small the unit speed is not always quicker. Greek ferries. Surface Similar methods The reverse of moldings will have the Transfer molding (p.176) can achieve a fibrous texture of the reinforcement. similar strength. Gas-assisted injection Gel coats can be applied to the mold to molding (p.201) and reaction injection enhance the components’ surface finish. molding (p.199) can be used to create large Other thermoformed skins can be applied parts, but without the strength. Other in a secondary process for a superior alternatives include vacuum infusion surface. Vacuum-bag and pressure-bag (VIP) (p.154), filament winding (p.158), methods allow much greater surface detail. and autoclave molding (p.156). Types/complexity of shape Sustainability issues All methods are limited to open shapes All the processes are largely labor assisted with fairly thin cross-sections. Only slight and use a fairly low amount of energy. undercuts are possible, depending on how Use of natural fibers minimizes the use of far the component can be flexed when nonrenewable materials. Composites are removing it from the mold. difficult to recycle at the end of their life. Scale Yet their excellent strength and rigidity As big as you want. Hand lay-up allows ensures a prolonged lifespan. a much thicker wall thickness to be built Further information up than spray lay-up, which reaches its www.compositetek.com 5 maximum at about /8 inch. The scale of www.netcomposites.com components using the bag methods is www.compositesone.com limited only by the size of the bags. www.composites-by-design.com Tolerances www.fiberset.com Due to shrinkage, tolerances are hard to control for all methods.

LK016_P0114EDmakingIt2us.indd 153 16/09/2011 14:37 154 Thin & Hollow: Vacuum Infusion Process (VIP) Vacuum Infusion Process (VIP)

The vacuum infusion process (VIP) is reinforcing fibers are laid over a mold a method of forming composites that before the liquid resin is brushed or achieves density and strength in the sprayed into it. In the VIP process, end product by sucking the resin and the dry parts of the material are reinforcement fibers together into a stacked up over a mold. This is then dense, solid mass. In essence, it is an covered with a flexible sheet and a advanced form of contact molding seal is formed between the sheet and (see p.152) and, compared with similar the mold. The air is pumped out from techniques for forming composites, inside, forming a vacuum, and the it is a clean and highly effective liquid polymer resin is then fed into process through which the two main the fibers. The action of the vacuum ingredients can be combined in a means that the resin thoroughly single step. impregnates the dry material, which In traditional hand lay-up gives the final component its density methods in contact molding, the and strength.

1 A boat hull being covered in a 2 The sheet is inspected to make 3 The vacuum pumps that suck flexible plastic sheet, ready to be sure it is completely sealed. the air from between the sheet sealed prior to the application of and the hull. a vacuum.

LK016_P0114EDmakingIt2us.indd 154 16/09/2011 14:37 Thin & Hollow: Vacuum Infusion Process (VIP) 155

Volumes of production Typical products This is a slow production method that relies Propellers, marine components, and on the luxury of a fairly long setup time to equipment such as a stretcher used in build the part. rescue operations, which features an Unit price vs. capital investment aluminum frame over-molded with a VIP can be used in a small workshop with vacuum-infused composite. basic equipment, which can be purchased Similar methods from various suppliers. However, it requires Contact molding (p.152), transfer molding a lot of trial and error, and you may suffer a (p.176), and autoclave molding (p.156). high failure rate. Sustainability issues Speed This process is often carried out on a large Slow. scale, and its high error and failure rate Surface results in increased waste, most of which Gel coats can be applied to provide the cannot be reused. However, the fibers parts with a high surface finish. and resin are laid by hand which helps to Types/complexity of shape balance out the high amount of energy A common application for VIP is in required to heat the resin and power the the manufacture of boat hulls, which vacuum. Furthermore, the vacuum ensures should give you an idea of the level of its that only the minimum amount of resin complexity and its scale. is introduced to the fibers; any excess Scale is sucked out, which reduces material The process is suited to large parts. It is consumption and increases the strength difficult to make anything smaller than of the product. around 12 by 12 inches, because the fiber Further information needs to be draped over or inside the mold. www.resininfusion.com Tolerances www.reichhold.com Not the kind of process for high tolerances. www.epoxi.com Relevant materials As in any plastic composite method, typical resins used are polyester, vinyl ester, and epoxy, combined with reinforcements such as fiberglass, aramids, and graphite.

– Economical use of resin due to the – Complicated setup. efficient ratio of fiber to resin. – High degree of trial – Clean. and error. – Eliminates air pockets. – High failure rate. – Higher strength-to-weight ratios than contact molding (see p.152).

LK016_P0114EDmakingIt2us.indd 155 16/09/2011 14:37 156 Thin & Hollow: Autoclave Molding Autoclave Molding

Advanced composite materials applied pressure, it is one of the methods have applications across a range of of forming advanced composite industries, from premium branded components with particularly high sports products to engineering density. The process begins with components. These materials offer the application of reinforcing fibers superior strength in a lightweight and resin onto a mold, which can be molding. However, the combination of achieved through a variety of methods, the two distinctly different ingredients such as hand or spray lay-up techniques (various fibers and polymer resins) (see contact molding, p.152). A flexible in advanced composites provides bag is then placed, a little bit like a manufacturers with a challenge. They quilt, over the surface and the whole must find new ways to bring these raw thing is placed in an autoclave (a materials together in a cost-effective sealed chamber), where heat and manner that is suited to industrial between 50 and 200 psi of pressure production. The use of heat and are applied, forcing the bag to squeeze pressure is a very common element itself into, or around, the mold, within manufacturing. In autoclave compressing the resin and fibers molding the combination is used to together. This forces out any potential compact the raw materials together air gaps and allows for a relatively to offer the highest level of strength. fast curing time, compared with hand Autoclave molding is a modified or spray lay-up. It is the squeezing form of pressure-bag forming (see together of materials under pressure, contact molding p.152)—the composite with the application of heat, that is formed in what is essentially a gives the final component a very pressure cooker. As a result of the high density.

LK016_P0114EDmakingIt2us.indd 156 16/09/2011 14:37 Thin & Hollow: Autoclave Molding 157

Volumes of production Typical products Batch production to medium-level Widely used in the aerospace industry to production. fabricate high strength-to-weight ratio Unit price vs. capital investment parts for aircraft, spacecraft, and missile Molds can be manufactured from a range of nose cones. materials, including modeling clay, which Similar methods allows reasonably cheap tooling to be All forms of contact molding (p.152), produced for short-batch production. the vacuum infusion process (VIP) (p.154), Speed and filament winding (p.158). Although the laying together of the resin Sustainability issues and reinforcement can be automated, the The combination of intense heat and process requires manual labor and the pressure applied over several hours during material must pass through a number of autoclave molding results in high energy stages. The time the material spends in use and increased emissions. However, the autoclave can be up to 15 hours. the use of heat improves the performance Surface and surface quality of the material, which Gel coats are sometimes used on the may prolong the life of the product and surface of the mold to provide a higher prevent it entering the waste stream. quality surface finish. Without this gel, the Unfortunately, composites are difficult to surface would have a fibrous texture. recycle as it is very hard to separate the Types/complexity of shape combined materials. Although the process is versatile in terms Further information of being adaptable to different shaped www.netcomposites.com molds, it is nevertheless limited to fairly simple shapes. Scale Part sizes are only limited by the size of the autoclave. Tolerances Shrinkage does occur, so tolerances are hard to control. Relevant materials Suited to various advanced fibers, such as carbon fiber, and thermoset polymers.

– Increased density, faster cure times, – Suitable only for and void-free moldings compared making hollow parts with molding methods that use that have thick, neither heat nor pressure. dense walls. – Potential for molded-in color.

LK016_P0114EDmakingIt2us.indd 157 16/09/2011 14:37 158 Thin & Hollow: Filament Winding Filament Winding

Imagine impregnating the thread on The sticky fiber is wound over a pre- a cotton reel with resin and then being formed mandrel in a process that is able to pull the wound thread off its reel allowed to continue until the required to form a rigid plastic cylindrical part: thickness of material is built up. The this is the essence of filament winding. shape of the mandrel determines the In filament winding, a internal dimensions of the finished reinforcement fiber combined with a product. If the end product is likely polymer resin is used to form strong, to be used in pressurized conditions, hollow composites. It involves a the mandrel may be left inside the continuous length of tape or roving winding to add strength. (in other words, fiber) that is pulled There are various forms of through a polymer resin bath. filament winding that differ only in the configuration of the winding. These include circumferencial winding, where the threads are wound in parallel like the cotton thread on a spool; helical winding, where the threads are wound at an angle to the spool (which gives a woven surface pattern that is instantly recognizable); and polar winding, where the threads are run almost horizontally to the axis of the spool.

Product spun carbon chair Designer Mathias Bengtsson Materials carbon fiber and polymer resin Country UK Date 2003

This chair is made using a helical winding technique, though the desired effect is more gappy than is usual for components made from filament winding. This highly decorative spun structure firmly establishes filament winding—a process most often associated with engineering composites—as a design application.

LK016_P0114EDmakingIt2us.indd 158 16/09/2011 14:37 Thin & Hollow: Filament Winding 159

1 Three composite tubes being 2 The yellow control arm feeds the 3 The helical winding pattern of formed on a three-spindle filament- resin-impregnated fibers onto the the fibers is clearly visible. winding machine. tube-shaped mandrel. (The resin bath is out of frame.)

1 Fibers are unwound from several reels at a time.

2 The fibers are pulled through a polymer bath, where a drum coats them polymer in resin.

carriage mandrel

tows 3 The impregnated threads, “tows,” are wound at an angle (this is helical winding) onto the pre-formed mandrel by a carriage that moves along the length of the part.

4 The resin acts like glue to hold the threads in shape. Once the resin has cured, the part can be removed.

LK016_P0114EDmakingIt2us.indd 159 16/09/2011 14:37 160 Thin & Hollow: Filament Winding

Volumes of production Tolerances Equally suited to one-off and high-volume Tolerance is controlled by the internal production. Economical mass-production diameter, which is determined by the size starts at approximately 5,000 units and can of the mandrel. range up to hundreds of thousands of units. Relevant materials Unit price vs. capital investment Generally used to reinforce thermosetting Foam tooling can be used for small runs plastic with glass or carbon fiber. or one-off production, as can existing Typical products aluminum bar stock, so costs can This is a process that is often used be kept down. for closed-pressure vessels such as Speed aeronautical components, tanks, and The speed is dependent on the shape rocket-motor housings. Because of the and desired wall-thickness of the final high strength-to-weight ratio of these component. However, by using a “pre-preg” parts, they are used as “stealth” materials system, in which the fibers are precoated in to replace metals in military hardware. resin, the process eliminates the need for The process is also used for its more a resin bath. Speed is also affected by the decorative capabilities in expensive number of “tows” of fiber that are used, so “designer” pens made from composite that multiple tows result in a faster covering materials (as well as in the chair pictured). of the mandrel. Similar methods Surface Pultrusion (p.99) and hand or spray lay-up The internal surface depends on the finish (see contact molding, p.152). on the mandrel, while the external surface Sustainability issues can be finished in a number of ways, Filament winding is largely automated including with machining. so requires electrical energy to power Types/complexity of shape the motors. The high speeds at which Produces very strong, thin- or thick- the machines can operate help to make walled hollow components, including efficient use of this energy consumption asymmetrical shapes. through large volume production. The high Scale strength-to-weight ratio is also significant Machines can be built to produce filament and offers weight savings. windings to a massive scale. An all- Further information plastic, 1,300-foot-long motor case for a www.ctgltd.co.uk NASA rocket with a 174-foot diameter was www.vetrotexeurope.com produced in the 1960s. www.composites-proc-assoc.co.uk www.acmanet.org

– Produces – Filament-wound components components with a will always have a woven surface very high strength- pattern unless they are post- to-weight ratio. finished.

LK016_P0114EDmakingIt2us.indd 160 16/09/2011 14:37 Thin & Hollow: Centrifugal Casting 161 Centrifugal Casting including true- and semicentrifugal casting, and centrifuging

Centrifugal casting is a process that one of the problems traditionally is based on a specific use of gravity. associated with metal, because the The same force that is at work when outer surface of the component is of lettuce leaves are spun in a salad such a fine grain that it is resistant spinner, or when people are rotated in to atmospheric corrosion (which is a a waltzer at a fairground, is employed common issue with pipes), while the to thrust a heated liquid material internal diameter is rougher, with horizontally against the inside of more impurities. a mold. Once the liquid has cooled, In semicentrifugal casting, either the finished part is taken out of the permanent or disposable molds are mold. In industrial manufacturing, employed for making symmetrical centrifugal casting is most often used shapes such as wheels and nozzles. to make large-scale metal cylinders It involves a vertical spindle around that require specific surface properties which the mold is held, like a spinning within the metal component. top. It also involves a slower rotation Centrifugal casting for metals than true centrifugal casting and parts can be broken down into three main can be “stacked”—in other words, variants: true centrifugal casting, semi- more than one part can be made at a centrifugal casting, and centrifuging. time because multiple molds can be As you may well have guessed, each attached to the spindle. Because the process uses a centrifugal force to material nearest the center (that throw molten metal against the inside is, nearest the spindle) rotates at a wall of a mold to produce a variety slower rate than the material farthest of shapes. away, small air pockets can occur in True centrifugal casting is used the component. to make pipes and tubes, and it involves Centrifuging is similar to semi- molten metal being poured into a centrifugal casting in as much as the rotating cylindrical mold. The mold spinning occurs around a vertical defines the outside surface of the final spindle, but it is used to produce small component, while the wall thickness multiple components. The metal is of the final tube or pipe is determined forced into the various mold cavities by the amount of material that is (which are only a short distance from poured in. This type of casting solves the spindle) to produce fine details.

LK016_P0114EDmakingIt2us.indd 161 16/09/2011 14:37 162 Thin & Hollow: Centrifugal Casting

Volumes of production Relevant materials From a relatively simple setup in Most materials that can be cast by other a jewelry workshop, to large-scale methods, including iron, carbon steels, industrial production, these are stainless steels, bronze, brasses, and alloys processes that can be used for batch- of aluminum, copper, and nickel. Two rather than mass-production. materials can be cast simultaneously Unit price vs. capital investment by introducing a second material during Depends on the specific type of production: the process. Glass and plastics can also low-cost graphite molds can be used for be used. small production runs (up to about 60 Typical products pieces), while more expensive permanent The casting of metals is based in heavy steel molds are used for larger runs of, industry, where it is used for hollow parts perhaps, several hundred. with large diameters. Typical parts made Speed by true centrifugal casting are pipes for Slow, but it varies depending on the the oil and chemical industries, and water- material that is used and the size, shape, supply components. The process is also and desired wall thickness of the part. used in the production of poles for lighting Surface and other street furniture. Semicentrifugal True centrifugal casting produces an outer casting produces axisymmetric parts, such surface of fine-grain quality. Due to the as storage containers for wine and milk, slower rotation speed of semicentrifugal boilers, pressure vessels, flywheels, and casting, the forces in the center of the cylinder liners. Jewelers use centrifuging casting are small, so gaps and porosity for more modestly sized metal and generally occur that need to be machined plastic parts. away after forming. Centrifuging enables Similar methods fine details to be produced. Rotational molding (p.137), although in Types/complexity of shape centrifugal casting the mold is rotated True centrifugal casting produces only at much higher speeds. tubular shapes. Semicentrifugal casting Sustainability issues produces parts that are axisymmetric Each of the centrifugal casting techniques (symmetrical around the vertical spindle) in relies upon continuous rotation throughout shape only. Centrifuging is more versatile, each cycle, which combined with the heat and can produce more complex shapes. required to melt the material is energy Scale intensive. However, no waste is produced True centrifugal casting can be used as the molten metal is added only until to form massive tubes up to 10 feet in the required thickness is reached, keeping diameter and 50 feet long. Wall thickness material consumption to a minimum. 1 can be between /8 and 5 inches. Semi- The fine finish of the outer surface attained centrifugal casting and centrifuging through casting also provides metals produce smaller parts. with several years of excellent wear- and Tolerances corrosion-resistance. 1 The tolerances can be as good as /50 inch Further information on the outer diameter when using www.sgva.com/fabrication_ metal molds. processes/rna_centrif.htm www.acipco.com www.jtprice.fsnet.co.uk

LK016_P0162EDmakingIt2us.indd 162 16/09/2011 16:51 Thin & Hollow: Centrifugal Casting 163

mold molten metal

1 Molten metal is poured into a sealed mold. 2 The mold is rotated around its axis at between 300 and 3,000 rpm.

3 The rotating action of the mold throws the metal 4 The finished component, removed from the mold. against the inside walls of the mold. The quantity of metal determines the wall thickness of the final component.

– Parts can be produced with good – Limited production mechanical properties in all base. directions, because the process results in nondirectional grain – Limited shapes orientation. achievable. – The strength of centrifugal castings is close to that of wrought metal. – With true centrifugal casting, the outer surface has a fine grain, which makes it more resistant to corrosion. – Can achieve economical production over short runs.

LK016_P0162EDmakingIt2us.indd 163 16/09/2011 16:51 164 Thin & Hollow: Electroforming Electroforming

This process has changed very little The “skin” ultimately becomes the since the early nineteenth century, final component once it is lifted off the when simple —a way of mold. Essentially, it is a step on from plating metals from their salts—was electroplating, in which the layer of developed out of the initial work of metal acts only as a coating for the British scientist Sir Humphry Davy on original shape. passing currents through electrolytes. Electroforming is based on Situated somewhere between a the electro-depositing of metal onto surface coating and a form-making molds. The shape that would, in technique, electroforming is a fairly simple electroplating, be coated (the unusual process. It is perhaps best cathode), in electroforming becomes a explained by way of comparing it mold onto which the metalizing source to growing a “skin” over a shape. (the anode) is grown, in a solution of electrolyte. An electrical current forces metal ions from the anode onto the cathode. Once a sufficient buildup mold (cathode) of metal has been achieved—and this is where it differs radically from electroplating—the component is anode separated from the mold. The mold does not necessarily have to be made from metals—it can be made from any nonconductive material, which can be electrolyte solution coated with a conductive outside layer before plating. The usefulness of electroforming 1 A negative mold of the part to be produced is placed in a bath of electrolyte lies in the fact that intricate flat and solution with the base metal. A current is three-dimensional patterns can be then applied, which forces ions from the easily reproduced without the need for base metal onto the mold to build up a layer of metal. expensive tooling, because the detail is created on the mold. The process is unique in that it creates a uniformly thin layer of material around the mold, component unlike press forming (see metal cutting p.59) and sheet-metal forming (see p.50), which stretches the metal and, in 2 When a sufficient buildup of metal so doing, leaves it an uneven thickness. has been achieved, the component is mold separated from the mold.

LK016_P0114EDmakingIt2us.indd 164 16/09/2011 14:37 Thin & Hollow: Electroforming 165

Volumes of production bent, a process that creates thick areas of Due to the length of time it takes to load material in corners. molds into the tank and produce the Relevant materials buildup of metal, this is not a process for Nickel, gold, copper, alloys such as nickel- high-volume or rapid production. cobalt, and other electroplateable alloys. Unit price vs. capital investment Typical products This is an economical way of reproducing A great deal of highly decorated, hollow designs that are intricately patterned Victorian silver tableware was produced without needing a large investment in using the technique. Today, it is still used tooling. The cost of electroforming is partly for highly detailed silverware, but it is also determined by the amount of metal used, used for technical laboratory apparatus so the final unit price will depend on the and in musical instruments—a French surface area of the mold and the thickness horn, for example. of the deposited metal. Similar methods Speed Simple electroplating, and as part of Slow, but depends on the amount of metal the micro-molding with electroforming to be deposited. process (see p.250). Surface Sustainability issues Due to the nature of this process (the fact One of the major concerns with that it uses a mold and parts are built electroforming lies in the use of toxic up gradually from tiny ions), the surface substances in the electrolyte solution. pattern can be highly intricate. However, systems have been introduced in Types/complexity of shape which a special cleaning process removes An ideal process for making multiple units of any chemicals and metals from the water, complex, highly decorative shapes. Making which enables it to be recycled back into the mold from materials such as wax, which the process to reduce waste. Despite this, can be melted out after electroforming, electroforming is still energy intensive means undercuts are possible. as it based upon the use of a continuous Scale electrical charge and so has relatively slow The only limitation is the size of the production rates. electrolyte bath that holds the mold. Further information Tolerances www.aesf.org Unlike other metal-forming techniques, www.drc.com electroforming can produce extremely high www.ajtuckco.com tolerances, where the buildup of material www.finishing.com is exactly the same anywhere on the part. www.precisionmicro.com This is unlike when a piece of metal is

– Excellent definition in detailing. – Fairly slow and thus expensive. – Generates a uniform thickness of metal. – Low tooling costs. – An easy way to replicate existing products. – High tolerance.

LK016_P0114EDmakingIt2us.indd 165 16/09/2011 14:37 5: Into Solid

168 Sintering 170 Hot Isostatic Pressing (HIP) 172 Cold Isostatic Pressing (CIP) 174 Compression Molding 176 Transfer Molding 178 Foam Molding 181 Foam Molding into Plywood Shell 184 Inflating Wood 187 Forging 190 Powder Forging 192 Precise-Cast Prototyping (pcPRO®)

LK016_P0166EDmakingIt2us.indd 166 16/09/2011 16:52 The transformation of a material into a solid state

This chapter deals principally with a group of processes that fall within the realm of “powder .” This term no longer adequately describes the advanced and wide-ranging technology that exists, nor the materials. The advanced materials that are used are not always in powder form, and they include ceramics and plastics as well as metals. Processes that in the simplest terms were based on compacting metal powders into shape and then sintering the “green” component to fuse the tiny particles together, can now be applied to many different (though mostly particulate) materials. The one exception to the powder metallurgy classification is forging, which involves transformation of an object from one solid state to another.

LK016_P0166EDmakingIt2us.indd 167 16/09/2011 16:52 168 Into Solid: Sintering Sintering including pressureless, pressure, and spark sintering, die-pressing and sintering

Sintering (a derivative of the word through the mold into the powder, “cinder”) was traditionally associated generating heat internally (in contrast with the manufacture of ceramic to the above methods, where heat is objects. The term is now, however, applied). Die-pressing and sintering also widely used in the much larger are used predominantly for ceramic manufacturing area of powder or metal powders. In this process, metallurgy. Essentially, sintering the powder is first die-pressed into involves heating a particulate material a “green” state of the required to just below its melting point until the form. This is then heated so that particles fuse together. the particles sinter, or, in other Various forms of sintering exist words, fuse together. in the metals, plastics, glass, and Sintering is used to achieve high ceramics industries. Pressureless density in parts made from materials sintering involves a powder being with high melting points, such as placed in a mold that is heated and tungsten and Teflon where low porosity vibrated, and then sintered. Pressure is needed. One of the characteristics sintering involves powder being of sintered parts, however, is that the placed in a mold, vibrated, and then porosity of the final component can heated, with pressure applied either be controlled, especially with certain mechanically or hydraulically. In spark materials. The porosity of some sintering, a pulsed current passes materials even after sintering can have

– Suited to components with varying – Requires a number wall thicknesses. of different stages. – Efficient use of materials. – Difficult to achieve high tolerances due – Capable of forming materials that to the decrease in are difficult to deal with in other overall volume in ways, especially very hard or brittle sintered parts. materials. – Parts have good nondirectional properties. – Can produce complex forms.

LK016_P0166EDmakingIt2us.indd 168 16/09/2011 14:43 Into Solid: Sintering 169

its advantages: bronze, for example, is There is also an advanced form, often used as a material for bearings, selective laser sintering (SLS) (see since its porosity allows lubricants to p.252), in which the application of heat flow through. An alternative method, is highly controlled. This method is which eliminates porosity, is hot used for rapid prototyping. isostatic pressing (HIP) (see p.170).

Volumes of production Tolerances Can be used for fairly low production Due to problems with shrinkage (there is volumes as well as for metal injection- a reduction in volume because of the molded parts (see p.216), which require increase of density as material flows into a minimum of 10,000 units. voids), high tolerances are generally hard Unit price vs. capital investment to obtain unless a part goes through a Tooling costs range from low to high, secondary pressing and compaction. depending on the specific process. The Relevant materials nature of the process also makes it highly A variety of ceramics, glass, metals, and efficient because there is no wasted material. plastic can be sintered. Speed Typical products This varies considerably depending on the One of the most interesting examples is material and the method used. For example, the production of bearings, where the once compacted into shape, in the pressure- natural porosity produced by the process less method parts are put onto a continuous- allows lubricants to flow through the actual belt furnace. Bronze typically needs 5 to 10 bearings. Other common examples include minutes at the center of the furnace to sinter, hand tools, surgical tools, orthodontic while steel needs a minimum of 30 minutes. brackets, and golf clubs. Surface Similar methods Although the finished parts can be porous, Hot isostatic pressing (HIP) (p.170) and visually there is no difference in finish cold isostatic pressing (CIP) (p.172). compared with, for example, a standard Sustainability issues high-pressure die-casting (see p.219) or Sintering involves several stages of metal-injection molding. There is also production, including intensive heating a range of finishes that can be used on as the materials used have high melting sintered parts, including electroplating, oil points. This significantly increases energy and chemical blackening, and varnishing. consumption. However, the process allows Types/complexity of shape for recovered waste materials such as Not suited to thin-walled sections. Shapes iron to be reprocessed with excellent must not have undercuts. end results. Scale Further information Scale is limited to the size of the www.mpif.org compacting press up to a maximum of 28 by www.cisp.psu.edu 23 by 15 inches. Larger presses can produce approximately 2,000 tons of pressure, with parts requiring 50 tons per square inch.

LK016_P0166EDmakingIt2us.indd 169 16/09/2011 14:43 170 Into Solid: Hot Isostatic Pressing (HIP) Hot Isostatic Pressing (HIP)

Product knife from the Kyotop range – Produces parts of high density with Designer Yoshiyuki Matsui Materials zirconia ceramic no porosity. Manufacturer – Because the process produces Country Japan a uniform pressure, the Date 2000 microstructure of the final The ceramic blade of this quality knife retains its components is uniform, without sharpness well, and has the added benefit that weak areas. ceramic does not impart any taste to food. The visible pattern, known as the “Sandgarden effect,” – Capable of producing larger parts is lasered onto the ceramic as a secondary process. than is possible with other powder- metallurgy processes. – Suitable for producing complex Hot isostatic pressing (HIP) is one of the shapes. main processes for forming materials – Provides an efficient use of material. that fall under the umbrella term – Improves toughness and cracking “powder metallurgy” (a term that now resistance in advanced ceramics. also refers to other particulate materials, including ceramics and plastics). Heat – Eliminates sintering (see p.168), which is a secondary process in and pressure, typically in the form other powder metallurgy-based of argon or nitrogen gas, are applied methods of production. to powder resulting in parts with no porosity and high density, without the need for sintering (see p.168). The word “isostatic” indicates that pressure is – Costly setup. applied equally from all sides. – Shrinkage can be problematic.

LK016_P0166EDmakingIt2us.indd 170 16/09/2011 14:43 Into Solid: Hot Isostatic Pressing (HIP) 171

Essentially, the process involves The process can be used either powdered materials being placed to form components from powder or inside a container which is subjected to consolidate existing components. to high temperature and vacuum In the latter case, there is no need for pressure to remove air and moisture a mold as the shape has already been from the powder. The resulting highly formed. HIP is often used for castings compacted component is uniformly that need to be made denser by and 100 percent dense. eliminating porosity.

Volumes of production Typical products HIP is generally suitable only for medium- The cost of the operation limits its use to scale production quantities, typically less high-spec components that require high than 10,000 pieces. physical and mechanical properties, such as Unit price vs. capital investment turbine-engine components and orthopaedic The process requires large setup costs with implants. In advanced ceramics, HIP is expensive components. used to form zirconia knife blades, silicon Speed nitride ball bearings, and oil-well drilling Slow. bits made from tungsten carbide. Surface Similar methods It is possible to achieve very high surface Cold isostatic pressing (CIP) (p.172). There quality with ceramics, but other materials is also a sort of injection molding that is may require subsequent machining suitable for ceramics. and polishing. Sustainability issues Types/complexity of shape Microshrinkage can occur during Simple to complex shapes are possible. solidification, which can weaken the part Scale internally and render it faulty, resulting HIP caters for a range of sizes, from in wastage. However, the defective parts components measured in fractions of an can be salvaged and recycled back into the inch to large-scale products up to several process to minimize material consumption feet in length. and the use of raw resources. Moreover, Tolerances the process causes the materials to Low. strengthen and densify, which means that Relevant materials wall thicknesses can be reduced further to Most materials can be used, including minimize material use. plastics, but the ones that are employed Further information most commonly are advanced ceramics www.mpif.org and metal powders such as titanium, www.ceramics.org various steels, and beryllium. www.aiphip.com www.bodycote.com http://hip.bodycote.com

LK016_P0166EDmakingIt2us.indd 171 16/09/2011 14:43 172 Into Solid: Cold Isostatic Pressing (CIP) Cold Isostatic Pressing (CIP)

The best way to sum up this process is to think of squeezing wet sand between your hands so that most of the water is forced out, leaving a fairly hard lump that resembles the inside of your hand. Although this sort of pressing can be done at elevated temperatures, cold isostatic pressing (CIP) is a method of forming ceramics or metal components at ambient temperatures from powders, and it involves the powder being placed in a flexible rubber bag, which squeezes around the mold when equal pressure is applied from all directions, compressing and compacting the Product spark plug powders into a uniform density. Materials alumina ceramic Manufacturer NGK The process provides a uniformity of compaction around the entire The spark plug is a common product but it is made component, unlike conventional forms using a little-known process. The white alumina is the part that has been made using CIP. of pressing, such as compression molding (see p.174), which require two-part molds. The process is broken down into two types: wet bag and dry bag. In Wet-bag method wet-bag pressing the rubber mold is placed inside a liquid, which, as you particulate would expect, transmits the pressure material from all directions. In dry-bag pressing, the pressure is exerted from fluid which is pumped through channels in the tooling.

isostatic rubber pressure bag

A particulate material is placed in a rubber bag. Pressure is then applied, compressing and compacting the powder into a uniform density.

LK016_P0166EDmakingIt2us.indd 172 16/09/2011 14:43 Into Solid: Cold Isostatic Pressing (CIP) 173

Volumes of production Relevant materials Dry-bag presses are typically automated Advanced ceramics and other refractory from the powder-filling to the part-removal materials, titanium alloys, and tool steels. stage, but this is a low-volume production Typical products method used to produce parts in their The process is suited to products that are thousands rather than tens of thousands. used in harsh, aggressive environments, Unit price vs. capital investment such as cutting tools, advanced ceramic Tooling can be expensive for large production components including carbides, and runs, although existing tooling can be refractory components. Other applications customized for short-batch production. for pressed ceramics and metals include Speed automotive cylinder-liners for aircraft and This depends on the particular process—for marine gas turbine components, corrosion- example, in the wet-bag method the rubber resistant components for petrochemical mold is removed from the liquid after each equipment and nuclear reactors, and cycle and refilled. The dry-bag method, medical implants. However, the most however, has the bag as an integral part of common product that is made by CIP the mold so it does not need to be removed, is the spark plug. but is reused to form multiple parts. Similar methods Surface Hot isostatic pressing (HIP) (p.170). It is Depends on the component. Simple forms also possible to use injection molding will not need any further finishing. for ceramics. Types/complexity of shape Sustainability issues The wet and dry methods are suited to Cold isostatic pressing consumes far less different complexities of shapes. The wet- energy than its hot-forming counterpart bag method is used for complex components because heat is not used in either the wet because of the flexible mold, which allows or the dry method. Its high productivity for easy removal of the component. It allows level is energy efficient and it requires complex shapes to be produced, including minimal maintenance and replacement undercuts and re-entrant angles such as parts. Pressure and decompression help to collars and threads. The dry-bag presses decrease the forming of internal stresses are suited to simple shapes that can be and cracks, thus minimizing wastage easily removed from the molds. through faulty parts. Scale Further information The wet-bag method is suited to large www.dynacer.com shapes, while the dry-bag presses are www.mpif.org suited to smaller components. Tolerances

1 ± /100 inch or 2 percent, whichever is greater.

– The main advantage of CIP over – Low production other powder metallurgy methods rates. lies in its ability to produce parts with a uniform density, with predictable shrinkage rates on a larger scale.

LK016_P0166EDmakingIt2us.indd 173 16/09/2011 14:43 174 Into Solid: Compression Molding Compression Molding

This process can be pressed into service for forming several different materials. On the one hand, it is used for producing ceramics, and on the other, it can be used to mold thermoset plastics (it was the original method for forming Bakelite), as well as fiber- based plastic composites. To understand the basic principle of compression molding, just think of children jamming their fists into lumps of dough to create imprints.

Product electrical plug Materials phenol-formaldehyde plastic, also known as phenolic or Bakelite

A ubiquitous product that is an invaluable part of everyday life, but the process that lies behind it is frequently undervalued.

male mold press raw material heat pin female mold

1 A two-part mold is heated 2 A press brings the lower 3 The molds are separated and and the granulated material (or and upper parts of the heated the formed component is ejected sometimes a pre-form) is placed mold together, compressing by pins. in the mold. the material into shape, the thickness of which is determined by the distance between the male and female parts.

LK016_P0166EDmakingIt2us.indd 174 16/09/2011 14:43 Into Solid: Compression Molding 175

The elaborated industrial process male and female molds can be used uses granules as a starting point to process anything from thick, solid rather than solid material, and heated shapes to thin-walled containers. molds to replace the fist. The two-part

Volumes of production Relevant materials Can be equally suitable for batch or high- Ceramics and thermoset plastics such volume production. as melamine and phenolics, and fiber Unit price vs. capital investment composites and cork. In relation to other plastic-molding Typical products methods (for example, injection molding, Melamine kitchenware (bowls, cups, see p.196), tooling costs are moderate while and similar products) is often made with still maintaining a low unit price. compression molding. Other applications Speed include electrical housings, , Speed is affected by how long the mold and handles. remains closed, which is determined by Similar methods part size and material. Hand and spray lay-up molding (p.152) and Surface transfer molding (p.176). And, although Good surface quality. more expensive, injection molding (p.196) Types/complexity of shape could also be considered. Compression molding is often used for Sustainability issues large plastic parts with thick wall sections, These depend upon the type of material which can be more economically produced used. As the process is often used for with this process than with injection thermoset plastics, recycling parts made molding. The nature of shaping objects with this group of plastics is not an option. with a two-part, male/female mold makes Wastage can be high because of the excess the process suitable for simple forms with of material required to hold the material no undercuts, but it also means that parts being formed firmly within the mold. can have variable wall thicknesses. Further information Scale www.bpf.co.uk Generally used for small parts of www.corkmasters.com approximately 12 inches in any direction. www.amorimsolutions.com Tolerances Fair.

– Ideal for forming thermoset – Limited in terms plastics. of complexity of shapes, but good – Ideal for producing parts that for producing flat require large, thick-walled, solid shapes such as sections. dinner plates. – Allows for variable sections and wall thicknesses.

LK016_P0166EDmakingIt2us.indd 175 16/09/2011 14:43 176 Into Solid: Transfer Molding Transfer Molding

An alternative to compression molding (see p.174) and with some of the benefits of injection molding (see p.196), transfer molding is typically used to make large moldings with varying wall thicknesses and fine surface detail. The process involves a polymer resin being heated and loaded into a charger, where a plunger compresses the material. The heated material is Product body panels for a London bus Materials glass-filled thermoset plastic then “transferred” to a closed mold cavity. The defining characteristics The exterior body panels on this type of bus have been made using transfer molding. The easy flow of transfer molding are this heating of of material through the mold cavity means that the material before it is transferred, large components can be made without sacrificing and the use of a closed mold. They control of the wall thickness. allow the easy flow of the material through the cavity, which results in a finer degree of control over thin- walled sections and the ability to achieve fine detail on parts. Composite pump polymer materials can be made by mixing resin air fibers with the resin, or by laying the reinforcing fibers in the mold itself.

catalyst material

mixing head air vents

plunger

mold fibers

A polymer resin is heated and loaded into a charger. Here a plunger compresses the material and “transfers” it into a closed mold cavity.

LK016_P0166EDmakingIt2us.indd 176 16/09/2011 14:43 Into Solid: Transfer Molding 177

Volumes of production Tolerances Although traditionally associated with low- Because the process involves the use of volume production, recent developments a closed mold, it achieves a greater have allowed transfer molding to evolve tolerance than is possible with, for example, into a full-scale industrial process. compression molding (see p.174). Unit price vs. capital investment Relevant materials Because of the reasonably fast cycle times, Most often used are thermoset plastics transfer molding suits high production and composites. runs, which confers the benefit of low unit Typical products costs but, as you would expect, entails high Toilet seats, propeller blades, and tooling costs. automotive components (such as the body Speed panels for the bus, illustrated) are often This varies very much depending on the made using transfer molding. size of the part and the fiber content. Small Similar methods parts can have cycle times as low as three Compression molding (p.174), although minutes, while up to two hours is normal it has several drawbacks compared with for large and complicated moldings. transfer molding, and injection molding Surface (p.196), which is not as well suited to A good surface finish is achievable similar forming composites. The vacuum infusion to that produced by injection molding process (VIP) (p.154) can also be used for (see p.196). forming composites. Types/complexity of shape Sustainability issues Similar to injection molding, but bear in Transfer molding is capable of producing mind that complex moldings can increase large-scale parts to provide a more production cycle times considerably. efficient alternative to small-scale molding Scale techniques; it eliminates the need to It is possible to achieve a much larger scale form several different parts, and can than with, for example, injection molding. therefore reduce material and energy use In one recent example, the Ford Motor in subsequent processing. In addition, the Company was able to swap the entire closed mold significantly reduces styrene 90-piece front end of the Ford Escort for emissions. a two-piece transfer-molded assembly. Further information www.hexcel.com www.raytheonaircraft.com

– Reasonably fast production rates. – Inefficient use of materials due to – Allows complex and intricate parts excess material left to be produced. in runners during the – Allows large components with molding process. varying, thin- and thick-walled – Expensive tooling. sections to be produced.

LK016_P0166EDmakingIt2us.indd 177 16/09/2011 14:43 178 Into Solid: Foam Molding Foam Molding

Unlike many other plastic-processing temperature and pressure inside them methods, the production of expanded to equalize. The beads are reheated plastic foam requires the material—in and steam is used to inject them into the case of the chair illustrated here, the mold and to fuse them together. (It expanded polypropylene (EPP)—to is also possible to perform the initial go through a pre-expansion process expansion of the beads within the final before it can be manufactured. It’s mold, rather than injecting the already a bit like preparing the ingredients fused beads into the mold.) The mold before you embark on a recipe. itself is similar to a mold that might The raw material consists of tiny be used in injection molding (see beads, which, before molding, are p.196), with a cavity to form the final expanded to 40 times their original component. This recipe for molding size using pentane gas and steam. This plastics produces materials that are up causes the beads to boil, after which to 98 percent air. they are allowed to cool and stabilize. Enzo Mari’s design for the A partial vacuum is formed inside Seggiolina POP child’s chair utilizes each bead, and the beads are then these properties in a way that celebrates stored for several hours in order for the the material itself. This is in contrast to

steam and pentane aluminum plastic mold beads

steam

1 The raw material of 2 Once cooled, a partial 3 The final stage 4 Once cooled, the tiny spherical plastic vacuum is formed involves the beads formed part is removed. beads is expanded inside the beads, being reheated with to about 40 times its which are then left for steam, inside an original size by the approximately 12 hours aluminum mold. combined use of steam to allow the pressure and pentane. to equalize with the external environment.

LK016_P0166EDmakingIt2us.indd 178 16/09/2011 14:43 Into Solid: Foam Molding 179

its more general applications, where it manufacturers have developed tends to be hidden away in a cardboard technology that enables expanded box or under upholstery. polypropylene to be molded directly As well as producing stand-alone into the casings of other components, components and products, various reducing assembly times and costs.

Product Seggiolina POP chair Designer Enzo Mari Materials expanded polypropylene (EPP) Manufacturer Magis Country Italy Date 2004

The bright colors of the Seggiolina chair helps translate a traditionally industrial material and process into an intelligent, fun, and lightweight product for children.

LK016_P0166EDmakingIt2us.indd 179 16/09/2011 14:43 180 Into Solid: Foam Molding

Volumes of production Relevant materials High-volume production process. Expanded polystyrene (EPS), expanded Unit price vs. capital investment polypropylene (EPP), and expanded Aluminum tooling can be very expensive polyethylene (EPE). but produces highly cost-effective unit parts. Typical products Speed Surfboards and bicycle helmets, The molding cycle times are typically packaging including fruit and vegetable 1 to 2 minutes, depending on the material. trays, insulation blocks, head-impact Surface protection in car headrests, bumper cores, The material can be colored and printed and steering-column fillers, as well as with surface patterns, and graphics can acoustic dampening. be molded into the surface. The surface Similar methods is dependent on the density of the foam Injection molding (p.196) and reaction that you require, but all moldings will have injection molding (RIM) (p.199). the textured foam finish that is typical of Sustainability issues this type of material. It is also possible to The expansive behavior of the plastic produce different color combinations within beads reduces material use as the the same components, giving a mottled, hollow foam structure is predominantly multicolored effect. air. However, the extensive material Types/complexity of shape preparation prior to molding is energy Similar to the level of complexity that intensive because of heat and pressure is possible with injection moldings (see requirements that are repeated during p.196), but with thicker and chunkier walls. shape forming. The lightness in weight Scale is beneficial during transportation of the Foam molding is a very versatile process part, but materials are not recyclable. that is capable of producing parts as small Further information as 20 cubic millimeters up to blocks with www.magisdesign.com a profile of around 3 by 6 feet. www.tuscarora.com Tolerances www.epsmolders.org Tolerances vary a little between materials, www.besto.nl but in general it is possible to work to an accuracy of about 2 percent of the overall dimensions, with slightly higher figures for wall thicknesses.

– Very versatile in terms of scale and – Expensive tooling. application. – Improved structural properties. – Reduced weight.

LK016_P0166EDmakingIt2us.indd 180 16/09/2011 14:43 Into Solid: Foam Molding into Plywood Shell 181 Foam Molding into Plywood Shell

The constructional advantages and Product chair from the Laleggera lightweight qualities of veneers were range Designer Riccardo Blumer recognized by the makers of early Materials polyurethane foam and aircraft, such as the Mosquito, and wood veneers the structural use of thin veneers is Manufacturer Alias Country Italy nothing new in the manufacture of Date 1996 furniture. However, our interest in this engineered wood has now shifted “Laleggera” can be literally translated as “the light one,” and this chair amply deserves this to more innovative applications in description. The new manufacturing technique furniture production. that made it provides an interesting marriage of The construction of one materials not commonly used together. such example, the Laleggera chair (pictured), reveals a reverse type of tailoring. Starting with the thin veneers, the chair is constructed in the same way that a child might assemble a model kit, with a set of net shapes that are glued together at the edges, leaving a hollow shell with no structural integrity. To provide structural integrity, the shell is then injected with a polyurethane foam that, when cured, becomes rigid. This is an adaptation of the more conventional type of foam molding (see p.178), in which foam is injected through steam into an aluminum mold where it expands to form its own skin, and can then be removed from the mold. The great feature of the Laleggera range of furniture and the process developed by Alias is that it takes two highly uncommon materials and methods and brings them together to produce a new functional and aesthetic feature for furniture that is disarmingly lightweight.

LK016_P0166EDmakingIt2us.indd 181 16/09/2011 14:43 182 Into Solid: Foam Molding into Plywood Shell

Volumes of production Relevant materials This is a unique form of production so there The chair uses a combination of plywood are no points of comparison, nevertheless for the exterior structure and an internal the manufacturers state that more than structure of polyurethane foam. 8,000 chairs were produced in 2005. Typical products Unit price vs. capital investment The unique nature of the process means This information was not made available, that the only products manufactured are though it is fair to assume that a certain chairs and a table. However, there is no degree of experimentation would have been reason why the principle could not be required in order that the process be set up. extended to include other objects that However, the materials (a combination of require strength and lightweight properties. cut sheet material and injected foam) could Similar methods be experimented with, in a very low-tech, This production method has been created cost-effective manner. by Alias in cooperation with the designer Speed Riccardo Blumer. The manufacturers claim Each chair requires four weeks to produce that there are no other production methods from start to finish. similar to this one. The nearest comparison Surface contained in this book, though it produces The surface finish available with this type a very different sort of product, is inflating of production is totally dependent on the wood (p.184). plywood rather than the foam core. The Sustainability issues surface of plywood varies depending on The production process is heavily based on which type of wood is selected. manual labor. The lightweight structure Types/complexity of shape uses minimal materials with its thin The shapes are determined by the ability veneer skin and air-filled foam. Any waste of the plywood to be cut and assembled into veneer can be recycled, while the injection a hollow shell. of the polyurethane foam to fill the hollow Scale structure creates no waste. The reduction The table, which is the largest piece in in weight results in notable reductions in this collection, measures 94½ by 47¼ by energy used during transportation. 28¾ inches. Further information Tolerances www.aliasdesign.it Information not available, but it can be assumed that the tolerances are governed by the plywood and its ability to respond to injected foam.

LK016_P0166EDmakingIt2us.indd 182 16/09/2011 14:43 Into Solid: Foam Molding into Plywood Shell 183

1 The frame for a table is formed from a two- 2 The formed components ready for assembly. part male and female press.

3 The structure of the table is made by gluing 4 Presses form the plywood around the the formed components together. table frame.

– The combination – Trial and error required to achieve of materials the full production setup. creates strong but lightweight – Limited production base. components.

LK016_P0166EDmakingIt2us.indd 183 16/09/2011 14:43 184 Into Solid: Inflating Wood Inflating Wood

Wood may have been one of the materials used earliest by humans to produce objects, but there are many new methods of forming and transforming various forms of this basic material into new states. Most wood is transformed by being attacked with blades, but the process discussed below is a much gentler way of forming wood that relies to a large extent on the individual pattern of the grain to control the final outcome. The process of cross-grain laminating veneers of wood was invented by the ancient Egyptians; the technique of bending plywood to introduce curves developed far more recently; and the new process of inflating wood marks the next level of sophistication in wood forming techniques. Forming wood into compound curves has always been a costly and time-consuming process, however, designer Malcolm Jordan has created a unique way of forming plywood into a series of undulating and controlled forms, though the secret of the process remains undisclosed. The process started life as one of the many inspiring projects that have Product door panel Designer Malcolm Jordan come out of the three-dimensional Materials wood veneer with foam core design program at Brighton University, Manufacturer Curvy Composites on the south coast of England. Malcolm Country UK Date 2005 Jordan says, “My background is in aviation. I am a licensed helicopter The undulating, compound, organic curves that are engineer and being surrounded by the result of this unique process allow thin wooden veneers to take on a visual quality that is perfectly lightweight composite structures suited to the natural tactile warmth of wood. might have informed the line of experimentation. I tried a series

LK016_P0166EDmakingIt2us.indd 184 16/09/2011 14:43 Into Solid: Inflating Wood 185

of experiments with various core foam is introduced, and the unretained materials between thin plywood surfaces move freely to form compound skins.” The final product is a curves. The sizes of these wavy forms composite structure, with plywood and the technique are not restricted skins sandwiching a foam core. Areas to linear and parallel boards, but are of the plywood surfaces are clamped based solely on the predetermined in a retaining jig. Expanding liquid plywood stock sheet sizes.

Volumes of production Tolerances Most suited to batch production, rather Working with a natural material under than high-volume mass-production. pressure to freely form “unnatural” Unit price vs. capital investment three-dimensional shapes is not an exact Low capital investment and moderate unit process. Initially, there was difficulty in cost when compared with similar methods predicting the outcome of the curves, and (see below). the results were sometimes unexpected. Speed However, when pressure points have been Dependent upon the shape or product positioned and temperature and foam required—for example, in the case of a quantities are constant, visually similar batch of wall panels, the skins and frames results have been achieved. can be preassembled. The foam injection is Relevant materials a quick process, although the assembly can Polyurethane expanding foam (there are remain clamped in its retaining jig for up to variations with fire-retardant additives and eight hours to cure the foam. Output would versions without free icocyanates). Birch- therefore be accelerated with the use of faced aero-ply ranging in thickness from 1 1 multiple retaining jigs. /30 to /8 inch. Types/complexity of shape Similar methods Panels can be made either flat on one side Deep three-dimensional forming in and undulating on the other, or with two plywood (p.83) and foam molding into undulating surfaces that mirror each other. plywood shells (p.181). Because the plywood skins can be bent Sustainability issues before the foam is injected, the process does Plywood is manufactured from very thin not need to be restricted to linear or parallel slices of natural wood, a renewable and boards. Solid inserts can be installed during sustainable source. The expansive nature production for “hard points,” for example to of foam, which creates hollow air-filled enable the attachment of legs or fittings, or beads, also means that a small amount to join sections together. of material is consumed in relation to its Scale overall size. The foam-injection phase The scale is restricted by predetermined limits waste as the flow is stopped when plywood stock sheet sizes. It has the the shell is filled to the desired shape and potential for use in furniture, but there is size. However, pressure buildup sometimes almost certainly the possibility of a myriad causes the plywood to explode, creating an of sculptural and spatial applications for excess of material that cannot be reworked architectural and interior design purposes. back into the process. Further information www.curvycomposites.co.uk

LK016_P0166EDmakingIt2us.indd 185 16/09/2011 14:43 186 Into Solid: Inflating Wood

1 A metal jig is set up that will hold the 2 Final preparation of the plywood before the plywood panel. introduction of the foam.

3 Finishing the molded panel. 4 A cross-section of a sample showing the foam core.

– The resulting – Controlling the foam pressure. At component combines present the quantity and pressure lightness with of the injected foam is regulated via strength, distributing inlet- and outlet-restricting devices, the load through the although experience has shown plywood skins. that the pressure created can be enough to rupture the plywood – High-impact (with a big bang). resistance, with thermal and acoustic – Curving plywood can highlight isolation potential. flaws in the wood, often caused by manufacturing tools when the – Removes the plywood’s veneers were cut. Careful need for complex selection of plywood or a veneer molding techniques, added to the plywood overcomes this. hand carving, or machining. – Only available through one manufacturer.

LK016_P0166EDmakingIt2us.indd 186 16/09/2011 14:43 Into Solid: Forging 187 Forging with open- and closed-die (drop), press, and upset forging

Forging is a major process in metal forming, sometimes utilizing architectural-scale machines for pounding metals into shape. It is not only a method of forming metal, it also produces a change in its physical properties, resulting in enhanced strength and . In its simplest manual form—open-die forging—it involves a chunk of metal being heated to just above its recrystallization temperature and then being formed into shape by repeated blows with a hammer, as performed by a traditional . Movement of the work piece is the key to this method. In its more industrial incarnation, it incorporates several variations, including hot and cold . Closed-die (or drop) forging involves a very similar process to that of the open-die method described above. In this instance, however, the shaped hammer is held in a machine

Product raw, semifinished spanner Materials steel Manufacturer original manufacturer undisclosed, but finished by King Dick Tools in the UK Country Germany and UK

This unfinished ring spanner is the result of the closed-die forging process and is seen here before it is finished by drilling with a pilot hole and broached with a serrated tool to obtain the twelve points.

LK016_P0166EDmakingIt2us.indd 187 16/09/2011 14:43 188 Into Solid: Forging

and repeatedly dropped onto the Press forging involves a heated metal, which sits in a shaped die. bar being slowly squeezed between The shape of the two parts determines two rollers, which form the metal as the formed shape. Drop forging can it is fed through. Upset forging is used be either hot or cold. The hot form for shaping the ends of the rods by involves the blank metal being heated, compressing them as they are held in and results in stronger components the die. Typical products produced by due to the realignment of the grain. upset forging are nails or bolts.

“hammer” metal blank

flash

1 In hot closed-die forging, 2 The male and female parts of 3 The part is removed from the a metal blank is heated and the mold compress the metal, by mold ready for the flash to be placed in a die cavity. means of a hammering action, machined away. into the die cavity.

– One of the main reasons for – Forged parts often choosing forging is for the control require machining it gives over the grain structure to remove the excess in the metal. It allows for the metal that is left grain flow to be aligned to specific when the two halves shapes, making the part stronger of the die are brought and more ductile. together. – No gaps or voids occur in the metal, as they can in (see p.219) and sand casting (see p.228). – Less waste than with runners and sprues.

LK016_P0166EDmakingIt2us.indd 188 16/09/2011 14:43 Into Solid: Forging 189

Volumes of production Typical products From simple hand forgings up to about Because of the increased strength of forged 10,000 units. components (compared with cast metals), Unit price vs. capital investment a large number are used in aircraft engines In hot open-die forging, done by hand, the and structures. Other applications include cost is based on the skilled manual labor. hand tools such as hammers, In automated methods, tooling costs can and spanners, and swords—notably be very high. Samurai swords. Speed Similar methods Quite slow, which is partly due to the fact Powder forging (p.190). Impact extrusion that 90 percent of all forging processes are (p.146) and rotary swaging (p.106) are hot processes, so that the work pieces need both forms of forging. to be heated before forming. Sustainability issues Surface The increased strength the material Forged parts will generally need to be acquires during forging can increase the machined in order to achieve a good, smooth durability and lifespan of the final product. surface and to remove flash, which is the However, the heated forging techniques result of metal being squeezed out into a consume high amounts of energy, which flat web around the outside of the part. increases emissions and subsequent Types/complexity of shape effects on the environment. In addition, The type of forging process will dictate a significant amount of excess metal is the complexity and type of shape that is produced, and secondary machining and possible. In drop forging, draft angles are further energy use is required to trim it. generally required, and parting lines need Fortunately this excess can be recycled. to be designed in order for complex shapes Further information to be formed. Draft angles vary and are www.forging.org dependent on the type of metal used. www.iiftec.co.uk Scale www.key-to-steel.com Forging can be used for parts that weigh www.kingdicktools.co.uk from just an ounce or so to those reaching www.britishmetalforming.com half a ton. Tolerances High tolerances are difficult to achieve, partly due to the wearing of the die. Different metals offer a range of tolerances. Relevant materials With hot forging, most metal and alloys can be formed. However, the ease with which they can be forged varies enormously.

LK016_P0166EDmakingIt2us.indd 189 16/09/2011 14:43 190 Into Solid: Powder Forging Powder Forging AKA Sinter Forging

Powder metal forging is a process component. The pre-form is sintered that sits within the realm of powder to obtain a solid component, which metallurgy. It combines sintering is removed from the furnace, coated (see p.168) and forging (see p.187) to with a lubricant such as graphite, and produce finished parts. As in other transferred to a forging press. Here, the forms of powder metallurgy, the final component is formed in a closed- process begins with the forming of the die , which forces the metal metal powder into a “green” state in particles to interlock and become a a die. At this stage, the component is solid, dense mass. The extra compaction known as a “pre-form,” and is slightly provided by this process gives a highly different in shape from the final dense, nonporous component.

die

heat

pre-form

1 Metal powder is compressed 2 The pre-form is sintered to 3 The final component is formed into a “green” state in a die to obtain a solid component, which in a closed-die forge, which obtain the pre-form. is removed from the furnace, forces the metal particles to coated with a lubricant such as interlock and become a solid, graphite, and transferred to a dense mass. forging press.

LK016_P0166EDmakingIt2us.indd 190 16/09/2011 14:43 Into Solid: Powder Forging 191

Volumes of production Relevant materials High volumes, typically more than Most ferrous and nonferrous metals. A 25,000 units. large number of powder forgings use iron Unit price vs. capital investment with small amounts of copper and carbon. This high-volume production process is Typical products expensive, partly because of the need for Engineering components for a range of two sets of dies. Large volumes are needed industries, including automotive parts, to produce economical components. connecting rods, cams, hand tools, and Speed transmission components. Depending on the setup and the component Similar methods size, extremely high speeds are possible. Drop forging and press forging (p.187) Surface and compression molding (p.174). Good surface, which does not need Sustainability issues secondary processing such as . Powder forging offers greater precision and Types/complexity of shape less excess material than conventional The process is capable of producing complex forging, so requires only minor secondary shapes. Powder forging can accommodate processing to make more efficient use of a high degree of varying wall thicknesses, energy. It still requires high temperatures 1 which can be as low as /25 inch. Undercuts to create material flow and this has a are not possible. large impact on energy consumption Scale and emissions. In addition, over several Similar to drop forging and press forging hundred runs the intense impact pressure (for both, see forging, p.187)—think of between the die and the substrate a spanner or a gear (around 8 inches in material can result in greater diameter) for reference. maintenance requirements. Tolerances Further information Part of the advantage of powder forging www.mpif.org is its ability to produce parts with higher www.gknsintermetals.com tolerances than other forging methods. www.ascosintering.com

– No gaps or voids in the metal, – Expensive tooling which can occur in, for example, that requires sand casting (see p.228). large volumes of production. – Compared with other powder metallurgy processes, powder forging provides parts with greater ductility and strength. – Efficient use of material, with less wastage than in other forms of forging (see p.187). – Requires far fewer post-forming operations than other forging methods.

LK016_P0191EDmakingIt2us.indd 191 16/09/2011 16:53 192 Into Solid: Precise-Cast Prototyping (pcPRO®) Precise-Cast Prototyping (pcPRO®)

The Fraunhofer Institute in Germany block using information from a CAD is one of the world’s biggest research file. This mold is filled with a polymer organizations concerned with materials resin. Once the resin has hardened, and manufacturing. One method of the same milling machine cuts it to a production that has recently been precise final shape. The essence of this developed by the institute is precise- process is that it allows for one side of cast prototyping. a product (the molded side) to be Precise-cast prototyping replicated exactly each time the mold (or pcPRO®) is a method for rapid is filled, but the top (milled) side may be prototyping that combines casting and adapted according to the information milling operations in a single machine. contained in the CAD file. It is a two-stage process, with the first A product prototype usually stage involving a milling machine (see requires numerous adjustments before p.20) cutting a mold into an aluminum it is optimized, forcing the modelmaker

Product sample components Materials polymer resin Manufacturer Fraunhofer Institute Country Germany Date 2004

These sample components, shown from both the top and underside surfaces, are an example of the machined CAD-cut details. The cutting lines on the surface are visible, as is the flat cast side.

CAD-driven polymer milling machine resin

aluminum block

1 Information is used 2 The mold is filled 3 Once the resin has 4 The finished part to generate a CAD file of with a polymer resin. hardened, it is cut to is removed. the shape to be formed, a precise final shape which is fed into a by the same milling milling machine, where machine. the mold is cut into an aluminum block.

LK016_P0166EDmakingIt2us.indd 192 16/09/2011 14:43 Into Solid: Precise-Cast Prototyping (pcPRO®) 193

to start from scratch each time. With various electrical products, which precise-cast prototyping, however, have one side where the shape needs changes are only ever made in the to be fine-tuned, multiples can be cast CAD data. The main advantage is that using the mold, with only one side for components such as housings for being altered with CAD files.

Volumes of production Tolerances This is a CAD-driven process so it is suited Depending on the machine’s accuracy, to both one-off and batch production, commonly some 10 microns. though, obviously, the molded side remains Relevant material constant, so “one-offs” only differ on their A two-component resin. milled side. Typical products Unit price vs. capital investment Complex shaped parts with high-tolerance The tooling (the mold, in this case) is made outer surfaces and low-tolerance inner using the same machine that makes the surfaces. The process is used for the rapid component, which means precise-cast prototyping of bodies of cell phones, prototyping is highly cost-effective. cameras, automobile parts, and electric Speed and computer accessories. Milling of the mold typically takes between Similar methods half an hour and two hours; casting and Conventional milling (p.20) and casting curing of the resin and milling of each part methods. Other prototyping techniques, takes a minimum of an hour, depending on including stereolithography (SLA) (p.246). the part’s complexity. Sustainability issues Surface Molding, creating the form, and The surface quality corresponds with the machining the part in a single process normal quality of milled surfaces. allows for incredible energy efficiency on Types/complexity of shape many levels. By reducing the machinery The shape is limited only by the CAD used, energy consumption is cut drawing and the cutter (or cutters), dramatically, along with the emissions though extremely complex shaped parts from transportation of parts between or undercuts in the inner contour can be manufacturing locations. Alterations made by five-axes milling only (that is, to the milled surface can be carried out one cutter moving along five trajectories) immediately without the need for a whole and undercuts in the outer contour require new mold and test runs, significantly special mold inserts or silicone parts. reducing material use. Scale Further information The scale of the parts made on a standard www.fraunhofer.de machine is 10 by 10 by 6 inches.

– Permits the combination of – Limited number of automated and shape-specific manufacturers offer manufacturing. this method. – Time- and cost-effective. – High-quality finish.

LK016_P0166EDmakingIt2us.indd 193 16/09/2011 14:43 6: Comple

Parts with complex shapes and surfaces

These processes can be described as “plastic-state forming” because of the soft, malleable, and, generally, hot state of the materials as they are molded. It is these methods of production that are most responsible for the explosion in the number of cheap, molded plastic products now available. Nevertheless, the payback for achieving complexity at a low cost per unit is the level of investment required for tooling. This chapter contains many of the established methods of high-volume mass-production, such as injection molding in plastic and die-casting in metals. It also investigates methods of adding finishing materials to complex shapes.

LK016_P0194EDmakingIt2us.indd 194 16/09/2011 16:54 196 Injection Molding 199 Reaction Injection Molding (RIM) 201 Gas-Assisted Injection Molding 203 Mucell® Injection Molding 206 Insert Molding 209 Multishot Injection Molding 212 In-Mold Decoration 214 Over-Mold Decoration 216 Metal Injection Molding (MIM) 219 High-Pressure Die-Casting 222 Ceramic Injection Molding (CIM) 224 Investment Casting 228 Sand Casting 231 Pressing Glass 234 Pressure-Assisted Slip Casting lex 236 Viscous Plastic Processing (VPP)

LK016_P0194EDmakingIt2us.indd 195 16/09/2011 16:54 196 Complex: Injection Molding Injection Molding with water injection technology (WIT)

Is injection molding the mother of under pressure, pins eject the finished all plastic-processing techniques? It part from the mold. is through this process that we are Water injection technology (WIT), able to transform plastic into a mass or water-assisted injection molding, of packaging, toys, and casings for is a relatively new technology that electronics. It could well have been an promises several advantages over injection mold that French philosopher conventional injection molding Roland Barthes was referring to when and gas-assisted injection molding he wrote, in his Mythologies (1957), (see p.201). It is based on several of “. . . an ideally shaped machine, variations, which either employ tabulated and oblong (a shape well the injection of water to ram the suited to suggest the secret of an melt (polymer) into the mold, or use itinerary) effortlessly draws out a heap water injection as a means of forcing of greenish crystals, shiny and fluted the polymer outward, to the walls dressing-room tidies. At one end, of the mold, to create hollow parts. raw, telluric matter, at the other, The use of water eliminates some the finished, human artifact, hardly of the problems that are associated watched over by an attendant in a with gas-assisted injection molding, cloth cap, half-god, half-robot.” such as migration of the gas into the The process employs plastic plastics. In addition, due to the fact pellets, which are fed from a hopper that water cannot be compressed, a into a heated cylinder, which contains greater degree of pressure is produced a screw. The screw carries the hot than can be provided by gas, which plastic, slowly melting it, and finally results in several advantages in terms injecting it at high pressure into a of the complexity and finish of the series of gates and runners, which final parts. Faster cycle times are also feed the polymer into a water-cooled achievable due to the cooling effect steel mold. Once the part has solidified of the water.

Product BIC® Cristal® ballpoint pen Designer Marcel Bich Materials polystyrene (shaft); polypropylene (lid and plug) Manufacturer BIC Country France Date 1950

Millions of BIC® Cristal® ballpoint pens are sold worldwide every day. All the elements of this iconic ballpoint pen are made using injection molding, except for the cartridge and nib.

LK016_P0194EDmakingIt2us.indd 196 16/09/2011 15:06 Complex: Injection Molding 197

Volumes of production worth considering gas-assisted injection Small injection-molding manufacturers can molding (p.201), and, where thick walls be found to produce simple components of are required, try reaction injection molding 5,000 units or less. However, the minimum (RIM) (p.199). quantity is generally accepted to be Tolerances 1 10,000 units. ± /250 inch. Unit price vs. capital investment Relevant materials Unit price is very low, but this must be set Predominantly used for thermoplastics, against the high tooling costs, which can but thermosets and elastomers can run into tens of thousands of dollars. also be used. Speed Typical products Cycle times vary depending on the type of It is impossible to state “typical” products material, wall thickness, and the geometry produced by injection molding because of the part. As an example, simple bottle its use is so widespread, from candy caps have the fastest cycle times of packaging (tic tacsTM boxes, for example) between 5 and10 seconds. A common to medical implants. speed for more complex parts is between Similar methods 30 and 40 seconds. The equivalent process for metals is metal Surface injection molding (MIM) (p.216) or This is determined by the steel mold, and high-pressure die-casting (p.219). can vary from spark-eroded to highly glossy. Sustainability issues The points where ejector pins are located This process offers a precise, controlled, in the mold need to be considered when and optimized use of material and energy. designing a part, as these leave small, Water injection technology can help to indented circles. Parting lines, where the improve the energy efficiency of injection various parts of the mold come together, molding through faster cycle times and by also need to be considered. forming a closed-loop cycle in which the Types/complexity of shape water is not disposed of but is put back If the volumes of production are particularly into the process. However, with its ability great, injection molding can be used to churn out plastic parts quickly and to form highly complex parts. However, cheaply, injection molding can be accused features such as undercuts, variable wall of encouraging disposability as there is no thicknesses, inserts, and threads will add cost incentive to reuse products. It can also significantly to the cost of the tooling. come under fire for the release of toxins Generally, injection molding is suited during heating and further emissions to thin-walled sections. through high energy use. Scale Further information Micro-injection molding is a specialist www.bpf.co.uk area and there are certain manufacturers www.injection-molding-resource.org who specialize in parts that are often 1 less than /25 inch in size. For large-scale products such as garden chairs, it is

LK016_P0194EDmakingIt2us.indd 197 16/09/2011 15:06 198 Complex: Injection Molding

pellets

heat

electric motor

screw

1 Plastic pellets are fed from a hopper into a heated cylinder.

steel mold component

pin

2 The screw injects the polymer into gates and 3 The machine opens ready for ejection runners, which feed into the steel mold where of the component by a series of pins. the component is formed.

– Highly versatile in terms of – Involves considerable molding different shapes. investment and high production runs. – Highly automated production. – Can involve long lead – Cost-effective parts. times.

LK016_P0194EDmakingIt2us.indd 198 16/09/2011 15:06 Complex: Reaction Injection Molding (RIM) 199 Reaction Injection Molding (RIM) with R-RIM and S-RIM

Reaction injection molding (RIM) is a process that is used for producing reactive mixing structural foam components. Unlike resins chamber standard injection molding (see p.196), which uses pellets as the starting point, RIM involves feeding two reactive thermosetting liquid resins into a mixing chamber. They are then injected through a nozzle into the mold, where an exothermic chemical reaction produces a self- forming, smooth skin over a foam core. Depending on the formulation of the 1 A combination of two reactive resins is fed into resin, parts produced using RIM can a mixing chamber. either be soft foams or solid, highly rigid components. Composites can be produced by mold introducing short or long fibers into the mixture, to add reinforcement. This form of production can be broken down into two categories: reinforced- reaction injection molding (R-RIM) and structural-reaction injection molding (S-RIM). 2 From this chamber the resins are fed into the mold, where an exothermic chemical reaction produces a smooth skin over the foam core of the final component.

3 The cured part is removed from the mold.

LK016_P0194EDmakingIt2us.indd 199 16/09/2011 15:06 200 Complex: Reaction Injection Molding (RIM)

Volumes of production Relevant materials Suited to high-volume production, however, RIM is often used to form dense because of the potential to use inexpensive, polyurethane foams. Other common low-strength molds, low-volume materials include phenolics, nylon 6, production is also a realistic possibility. polyester, and epoxies. Unit price vs. capital investment Typical products This is a low-pressure process with low Large foam moldings, rigid and flexible tooling costs compared to those of standard alike, are manufactured using RIM for use injection molding (see p.196). However, in products such as car bumpers and trim, setup costs are high, so large numbers industrial pallets, casings for large-scale of units need to be produced in order to electronics, and refrigerator door panels. be economical. Similar methods Speed Injection molding (p.196) and transfer This is not a rapid process, unlike standard molding (p.176). Also, gas-assisted injection molding. Cycle times are injection molding (p.201), which allows for considerably longer and, depending on the complex, large lightweight parts, although size and complexity of the part, can take it is not suited to foams. several minutes, as opposed to seconds, Sustainability issues per part. Material use is considerably lower than Surface with conventional injection molding as The foams produced using this process are the expansive nature of the foam produces “self-skinning” and sometimes form a hard a predominantly hollow structure that skin similar in quality to that formed in better resists shrinkage while maintaining standard injection molding, while retaining excellent strength. In addition, the the foam core. heating temperatures are considerably Types/complexity of shape lower, which results in reduced energy Large and complex solid shapes are consumption and emissions. One possible, with the potential to create disadvantage is that the slower cycle times varying wall thicknesses in the same mean energy use is less efficient than it component. Typical wall thicknesses of is with conventional injection molding. 3 RIM parts are a chunky /8 inch. Materials, however, are not recyclable. Scale Further information Suited to large-scale components up www.pmahome.org to 6½ feet long. www.rimmolding.com Tolerances www.plasticparts.org High tolerances.

– Allows for varying wall thicknesses within the same part. – Because of the low pressures and temperatures required for this process, tooling costs can be low compared with other high-volume plastic methods. – A multiple-cavity – Produces parts with a high strength-to-weight ratio. mold is needed for – Suitable for making large parts. small parts.

LK016_P0200EDmakingIt2us.indd 200 16/09/2011 16:55 Complex: Gas-Assisted Injection Molding 201 Gas-Assisted Injection Molding

In standard injection molding, definition in the part, or a larger surface thermoplastics are heated and injected area, is required. This is achieved into a mold (see p.196). Channels in the by injecting a very thin layer of gas mold act to cool the plastic part before between one surface of the plastic and it is released from the mold. During its adjoining mold cavity. cooling, the part shrinks and moves Exploiting the reduction in weight away from the walls of the mold and, provided by this process, the Italian to compensate for this, more material is manufacturer Magis has produced a injected into the mold. range of furniture that redefines the An alternative to this widely rules for designing large-scale plastic used method is to inject gas, usually products. The ubiquitous low-grade nitrogen, into the mold cavity while garden chairs, produced by standard the plastic is still in its molten state. injection molding, that you find in This internal force counteracts the your local hardware store are made shrinkage by inflating the component, with a thin cross-section and have a forcing it to remain in contact with the strong, stable structure. By contrast, surface of the mold until it solidifies, the Magis range, designed by Jasper resulting in parts with hollow sections Morrison, appears to be solid, but the or cavities. inside is hollow. There are two types of gas- assisted injection molding: internal and external molding. The former is the most widely used, with the external method being used when greater

Product Air-Chair Designer Jasper Morrison Materials polypropylene, with glass-fiber reinforcement Manufacturer Magis Country Italy Date 1999

This stackable chair, while sturdy enough to withstand considerable bulk, is lightweight, hollow, and economical, all of which are the advantages of using gas-assisted injection molding.

LK016_P0194EDmakingIt2us.indd 201 16/09/2011 15:06 202 Complex: Gas-Assisted Injection Molding

Volumes of production Relevant materials Strictly a high-volume production process. Most thermoplastics, including Unit price vs. capital investment high-impact polystyrene, talc-filled Like standard injection molding (see p.196), polypropylene, acrylonitrile butadiene it combines low unit costs with styrene (ABS), rigid PVC, and nylon, high investment. and also composites. Speed Typical products Due to the fact that material is injected only Virtually all moldable parts can be made once and cools more quickly than it would using gas-assisted injection molding. in standard injection molding, cycle times External gas-assisted injection molding are reduced. is often used for components with large Surface surface areas, such as car-body panels, One of the key advantages of this form of furniture, refrigerator doors, and high-end injection molding is the superior finish. plastic garden furniture. During standard injection molding, stress Similar methods usually occurs along the flow line inside Injection molding (p.196) and reaction the mold, resulting in warping. The injection molding (RIM) (p.199). introduction of gas helps to distribute the Sustainability issues pressure evenly and eliminate the stress and Gas-assisted injection molding can allow flow lines in the plastic at specific points. for significant reductions in material use as Types/complexity of shape hollow, lightweight parts can be produced. Injection molding is one the best methods Cycle times are also much faster, with of producing complex shapes, and gas- significant savings in energy consumption assisted injection molding is no exception. in comparison to traditional injection Depending on how much you want to molding. In addition, the reduction in spend on tooling and the number of parts weight can be beneficial in reducing fuel in the mold, you can achieve some highly consumption during transportation of complex shapes. the product. Scale Further information From casings for small electronic www.magisdesign.com components to large pieces of furniture. www.gasinjection.com Tolerances With greater control over the material and less shrinkage than in standard injection molding, tolerances are higher.

– Allows for components to be made – Because of the with variable wall thicknesses. extra parameters involved—handling – Reduced cycle times. of gas, regulation – Reduced weight. of pressure, and cooling—potential – Less sink marking than in problems need to conventional injection molding be addressed in (see p.196). advance, requires – Consumes 15 percent less energy experience, and than standard injection molding. often, a fairly complicated setup.

LK016_P0194EDmakingIt2us.indd 202 16/09/2011 15:06 Complex: MuCell® Injection Molding 203 MuCell® Injection Molding

The traditional injection molding technique has been used to mass- produce plastic components for everything from cell-phone casings to shoes for more than 50 years. With the evolution of new composite materials, it is no surprise that MuCell® injection molding has evolved along with them. MuCell® is a process that can be applied to both injection molding and extrusion, but introduces a new substance—microcellular foam—into the mix. On average the process allows for a weight reduction of 10 percent and reduced molding cycle times of 35 percent. A polymer mixed with a foaming agent is forced into the mold cavity under very high pressure. Once the polymer has spread throughout the cavity, nitrogen gas is shot into the mold at a very high heat at which it reaches a point between being a vapor and a liquid. This is called the

Product HVAC valve component Materials Talc-filled, PP (black plastic molded with MuCell®; second sealing gasket molded in solid with thermoplastic elastomer Manufacturer Valeo Country Germany

MuCell® technology is used in this product to create a strong but lightweight (7 percent) component. The material is dispersed equally, which results in less shrinkage of the part.

LK016_P0194EDmakingIt2us.indd 203 16/09/2011 15:06 204 Complex: MuCell® Injection Molding

“critical temperature” and is crucial it were conventionally molded. There to the behavior of the polymer. Once is also a closer compliance to mold the gas reaches a higher temperature shape and dimensions because of the than this it dissolves into the molten expanding nature of the foam. The polymer. However, as the pressure uniform structure provides the inside the mold begins to decrease molded product with excellent the gas changes state again, and stiffness in addition to thermal and separates to form a consistent cell conductive insulation. structure within the polymer. The cells The technique is not suitable are microscopic in size but they have for everyday molded products, but incredible strength while being very has been designed for engineered low in weight. The polymer mix has plastic components that require now formed a microcellular foam. high precision and accuracy. It is a Because the structure of the single-phase process—the polymer microcells is consistent and uniform, and gas are injected within the same the stress within the mold cavity is cycle—and increase in material flow dispersed equally, which results in provides the potential for producing less shrinkage than there would be thinner parts. To give an idea of the in traditional plastics, which do not scale the process works with, the have a uniform structure. The molded parts it produces typically have a wall 1 product is significantly lighter in thickness of no more than /8 inch. weight and has less viscosity than if

– Weight of molded parts is – Limited number of significantly reduced. manufacturers. – Increased dimensional stability because of the uniform cell structure. – Cycle time is reduced due to the reduction in weight and viscosity. – No shrinkage during cooling.

LK016_P0194EDmakingIt2us.indd 204 16/09/2011 15:06 Complex: Mucell® Injection Molding 205

Volumes of production Tolerances

1 The process is applicable to high-volume ± /250 inch. production runs that are comparable with Relevant materials injection molding or extrusion. A range of thermoplastics, of which Unit price vs. capital investment engineering plastics such as PA, PBT, Reduced cycle time and usage of materials PEEK, and PET are known to perform lowers the cost significantly compared with better. Materials often perform better traditional injection molding. However, when filled with fillers such as glass fibers. the process requires investment in specific Typical products equipment that costs more than that used Most of the key applications for this for conventional injection molding. process are currently based on automotive Speed components because of the reduced The manufacturers maintain there is a weight of the molded parts. Applications 15 percent to 35 percent improvement in for base plates for power tools have cycle times compared with conventional been implemented, where nylon filled injection molding of thermoplastics. with glass fibers replaces metals while Surface maintaining the flatness needed in this The use of the gas creates parts with type of application. increased flatness and with less potential Similar methods to warp. Gas-assisted injection molding (p.201). Types/complexity of shape Sustainability issues The process offers the ability to create Material consumption is significantly finer details and thinner wall thickness reduced due to the expansion of the foam, than conventional injection molding which in turn decreases the weight of the or extrusion. component. The viscosity of the material Scale is less, thus speeding up cycle times and The size of components that can be making efficient use of energy. produced typically ranges from something Further information the size of a latch pin weighing a fraction www.trexel.com of an ounce to a large automotive part weighing several pounds. Typically the wall thickness of MuCell® parts is less than 1 1 /8 inch, /10 inch for talc-filled PP.

LK016_P0194EDmakingIt2us.indd 205 16/09/2011 15:06 206 Complex: Insert Molding Insert Molding

Insert molding is a branch of (see p.196) is the dominant element in multicomponent molding (also called this method of manufacture, with the two-shot molding), which is a method inserts being placed in the mold prior of combining different plastics in the to the injection of plastics. course of only a single manufacturing Multicomponent insert molding process. Insert molding refers to the using injection molding exists in two stage of the process where parts (made forms. In the first method, known from a variety of materials, including as rotary transfer, two materials are metal, ceramic, and plastics) are injected into the same mold cavity inserted to increase strength in the with the mold having been rotated. plastic component. Injection molding The second method, commonly

Product Stanley DynaGrip Pro screwdriver Designer Stanley in-house design Materials the handle is made of four layers —the first is nylon, followed by two layers of different colored polypropylene, and finally a thermoplastic elastomer (TPE) grip Manufacturer Stanley Tools Country UK Date 1998

This screwdriver consists of four layers of plastic molded over the metal shank: the first, blue molding can be seen at the end of the handle; the shiny black area is the second layer; the yellow graphics are the third; finally, the black grip.

LK016_P0194EDmakingIt2us.indd 206 16/09/2011 15:06 Complex: Insert Molding 207

referred to as “robot transfer,” There are also other forms involves a component being produced of insert molding that, instead of first and only afterward being injection molding, use compression transferred to another mold for a (p.174), contact (p.152), and rotational second material to be added. (p.137) molding.

Volumes of production varying degrees. However, thermosets High-volume production process, typically and thermoplastic elastomers (TPEs), above 100,000 units. for example, generally do not provide Unit price vs. capital investment a chemical bond. An economical process when compared with Typical products manual assembly of the different materials. One of the key features of combining Speed different materials is that you are able Depends on the product. Thin-walled to bring together multiple functions in products cool very quickly, but the type of a single component. For instance, it plastic and overall component design are is possible to have movable joints and also important factors. decorative features over a flexible yet Surface strong core, without the additional assembly Depends on the molding process used, but costs. Typical products that are made is comparable to injection molding (see through this process include toothbrushes, p.196) but, in with insert molding, surface screwdrivers, razors, and housings (of, for materials may be introduced that can example, power tools with rubber grips). enhance the finish, for example the extra Similar methods grip on a toothbrush handle. In-mold decoration (p.212). Types/complexity of shape Sustainability issues Since this type of insert molding is based This process can eliminate the need on injection molding, the same possibilities for several stages of production and and restrictions apply, although the shape subsequent energy use by reducing of the insert itself will partly dictate the everything into one single step in one shapes achievable. location, making the most efficient use Scale of transportation and energy. However, It is possible to achieve products of greatly recycling becomes more difficult when two varying size depending on the type of or more materials are combined, as they injection molding used. need to be separated before they can be Tolerances reprocessed. Can be very high, because injection Further information molding can achieve tolerances of www.engel.info 1 ± /250 inch. www.bpf.co.uk Relevant materials www.mckechnie.co.uk Any combination of materials, including thermoplastic and thermoset polymers. Depending on the combination of materials, different layers may bond chemically to

LK016_P0194EDmakingIt2us.indd 207 16/09/2011 15:06 208 Complex: Insert Molding

Robot Transfer Method

pre-formed component

injected mold plastic die

1 Plastic is injected over a preformed component, 2 The molded plastic part (together with the shaft) in this case the metal shaft of a screwdriver. is removed by robotic arms and transferred into a separate die.

die

space to inject second plastic

3 At this point, a second plastic is injected over the 4 The finished component is removed from original molding. This process can be repeated as the mold. many times as necessary to build up the required number of materials.

– Allows a range of differing – High tooling costs. physical and tactile properties to be incorporated into a single – Requires an component. advanced degree of knowledge on – Reduced labor costs for assembly. how to combine the various materials, – Can add a whole range of increased and on subsequent functionalities. design considerations such as shrinkage and the stresses of one material over another.

LK016_P0208EDmakingIt2us.indd 208 16/09/2011 16:58 Complex: Multishot Injection Molding 209 Multishot Injection Molding

In contrast to traditional injection can be a lengthy process that requires molding where each component is each piece to be molded separately, often produced separately as a single piece, in different locations, along with an multishot injection molding makes additional manual assembly to complete it possible to mold several pieces production. Multishot injection molding and assemble them in a single cycle, makes production a lot less messy by resulting in a finished product in just one run. The process even allows for products with moving parts such as caps, handles, and hinges to be created within the same molding cycle. Generally, the manufacture of a product with several components

Product Garden secateurs Materials Thermoplastic Elastomer (TPE) grip, polypropylene handle, steel blades Manufacturer Country Finland

The cutaway of these secateurs show how the gray TPE is injection molded within the black PP handle.

LK016_P0208EDmakingIt2us.indd 209 16/09/2011 16:58 210 Complex: Multishot Injection Molding

eliminating all these secondary the machine processing. The designers processes and incorporating them examine several different ways of into one, which in turn significantly making a part as there is no single reduces lead time as well as costs. solution. Some methods may offer cost As with anything simple, savings while others may allow for a great deal of setup is required in flexibility in designing parts. order to maximize the process. Every A multishot injection molding aspect must be considered, from machine is automated and consists of how the combination of materials robotic arms that are controlled by will react with one another to the type a computer and move the component of machine that should be used. The from one mold cavity to another. design of the molding process is very creative because of the flexibility of

– Reduced production time. – Needs a great deal of production planning. – Reduced unit costs. – It is likely that the original – Multicomponent part design will require some produced in single cycles. alterations before it is – Up to four different suitable for manufacture. materials can be molded in – The robot sometimes one cycle. has difficulty picking – A variety of functional/ up and placing complex decorative features, components, which can including graphics, text, and result in moldings being grips, can be applied during dropped and misplaced. the process

LK016_P0194EDmakingIt2us.indd 210 16/09/2011 15:06 Complex: Multishot Injection Molding 211

Volumes of production Tolerances

1 There are small injection molders that ± /250 inch. produce simple components of 5,000 units Relevant materials or less. However, the minimum quantity is The process is suited to the thermoplastics generally accepted to be 10,000 units. family, but consideration needs to be given Unit price vs. capital investment to the compatibility of various types when The investment cost for machinery and mixing them in a component. design planning is high. However, the Typical products overall cost is lower in comparison with Medical and healthcare; automotive; traditional techniques due to a reduction in telecommunications; electronics; storage, assembly costs, transportation of appliances; cosmetics. components, and use of materials. Similar methods Surface For other methods that combine materials The steel mold allows for surfaces that see over-mold decoration (p.214), insert range from spark eroded to highly glossy. molding (p.206), and in-mold decoration The location of ejector pins in the mold (p.212). needs to be considered when designing Sustainability issues a part as they will leave a small indented As all parts are produced in one circle. Parting lines where the various parts process, energy use is very efficient and of the mold come together also need to transportation between locations for be considered. additional manufacturing is eliminated. Types/complexity of shape However, it is very difficult to separate If production volumes are particularly materials in multimaterial components, high multishot injection molding can which makes them problematic to recycle. be used to form highly complex parts. Therefore, consideration should be given However, elements like undercuts, variable to reducing the number of material types. wall thicknesses, inserts, and threads Further information significantly add to the cost of tooling. www.mgstech.com Scale www.fiskars.com Micro-injection molding is a specialist area and certain manufacturers specialize in 1 parts that are often less than /25 inch. For large-scale products like garden chairs it is worth considering gas-assisted injection molding or, for large wall thicknesses, reaction injection molding (RIM).

LK016_P0194EDmakingIt2us.indd 211 16/09/2011 15:06 212 Complex: In-Mold Decoration In-Mold Decoration

As the name implies, this is not a shape of the component to be molded, method of production as such, but, the foil is fed on a ribbon into the mold rather, in-mold decoration was (or is cut and individually inserted, if developed as an economical way of the part is curved). The process is also adding decorative surfaces to injection- suitable for shapes with compound molded plastic parts. It offers a curves, but in this case the foil needs way of eliminating the necessity of to be molded to shape before being having to print directly onto a part inserted into the mold. in a separate, post-forming process. One of the uses for in-mold This manufacturing technique is decoration is as an alternative to becoming more and more important spraying or molding parts in specific with the growing market for electronic colors. It is a way of applying color products, which makes increasing to products to ensure consistency use of graphics for keypads, product between moldings in different branding, and the personalizing of materials, where exact color matches portable consumer products. are hard to achieve. An example of The process begins with the use of this process can be found in the printing of the graphic onto a the back and front moldings of a cell polycarbonate or polyester film, phone, where the back is molded in known as a “foil.” Depending on the one material and the front in another.

Product Demonstration sample masks Materials The process has optimum effect on PBT plastic Manufacturer IDT Systems Country UK

Shown left are demonstration masks produced by IDT Systems to illustrate the depth of penetration that is possible with this system. These particular samples are made from PBT plastic with a translucent film.

LK016_P0194EDmakingIt2us.indd 212 16/09/2011 15:06 Complex: In-Mold Decoration 213

Volumes of production to produce color on moldings and to Suited to mass-production. add surface patterns. One of the most Unit price vs. capital investment interesting (albeit invisible) foils that can In-mold decoration is very cost-effective be applied is a form of “self-healing” skin. compared with painting or spraying parts This protective layer helps to keep handheld in a separate process. products, such as cell-phone casings, Speed shiny and free from scratches. Other As you might imagine, inserting the film applications include decorative cell-phone has a slightly negative effect on the overall covers, machine fascia, digital watches, cycle times, but this step can be automated keypads, and automotive trim, to mention and it needs to be considered in relation just a small selection of products. to the time it would otherwise take to Similar methods decorate a part by, for example, painting it. Over-mold decoration (p.214) is similar, Surface but involves the application of materials, Different films can be used to give a variety rather than foils, to a molding. Sublimation of finishes ranging from the functional to coating is another alternative, although the decorative. it is applied as a secondary process after Types/complexity of shape molding and is particularly suited to In-mold decoration can be used on both engineering polymers such as nylon. simple and complex compound curves. Sustainability issues Scale By combining decoration with production, As injection molding (see p.196). It is energy consumption can be significantly possible to make very small parts, but lowered as there is no additional the shapes need to be very simple. machining, power use, and transportation. Tolerances In addition, the decorative films can be Not applicable. used to enhance and protect the material Relevant materials surface, which can prolong the life of Polycarbonate, acrylonitrile butadiene the product. styrene (ABS), polymethyl methacrylate Further information (PMMA), polystyrene, and polypropylene. www.autotype.com.sg Typical products www.filminsertmoulding.com In-mold decoration is not just limited www.idt-systems.com to text-based graphics, but is also used

– Cost-effective to customize – Incurs additional parts and provide customer molding costs differentiation without retooling. because of the complexity of the – Allows for virtually any color, mold required to image, and even surface texture to accommodate be added as a skin. a film or foil. – Equally suited to short and long production runs. – Films can be used to offer surfaces that are scratch-, chemical-, and abrasion-resistant.

LK016_P0194EDmakingIt2us.indd 213 16/09/2011 15:06 214 Complex: Over-Mold Decoration Over-Mold Decoration

Over-mold decoration is not really a combination and imagine that the method of production in is own right, addition of the fabric would require but rather an extension of standard a whole new process involving someone injection molding (see p.196), as fixing the fabric by hand onto the part of a two-step process. What is plastic molding. In reality, this would particularly noteworthy about it is be labor-intensive and expensive. that it can give plastic components an Inclosia Solutions, a branch of Dow almost craftlike quality by the way it Chemical, has come up with the cleverly allows a different material to technology to combine plastic with cover the plastic in the mold. a range of other materials during the If you were to see a cell-phone molding process itself, eliminating the casing, for example, that has a small need for any secondary finishing. patch of fabric wrapped onto its surface, The benefit of this type of you might find it an interesting manufacturing is that it provides designers with a new set of materials, surfaces, and finishes to challenge traditional notions of plastic-molded products. Instead of electronic products having the same all-over plastic skin, they can have warm, tactile surfaces that are closer to textiles or to crafted materials such as wood. The process offers the possibility of extending our perception of products beyond the current boundaries of identical, mass- produced plastic, making it feasible for products to be “dressed” and become more integrated with our clothes, furniture, and jewelry. Product E-Go laptop Designer Marcel van Galen Materials fabric over a plastic molding Manufacturer Tulip Country The Netherlands Date 2005

The internal plastic molding of this laptop computer can be over-molded with a range of different materials to suit varying consumer markets. The leather and fabric “skins” allow for consumer electronics to be marketed in the same way as more fashion-led products, such as handbags.

LK016_P0214EDmakingIt2us.indd 214 16/09/2011 16:59 Complex: Over-Mold Decoration 215

Volumes of production Relevant materials High-volume production process. A variety of thin materials can be used Unit price vs. capital investment to over-mold, such as aluminum sheet, Unit price for components is more than that leather, fabric, and thin wooden veneers. for standard injection molding (see p.196). Typical products Tooling costs are higher due to the need to Over-molding has been used in a range incorporate a second material. of products that fall into the category of Speed personal mobile technology, including Because it is a two-step process that cell phones, Personal Digital Assistants involves forming a material over a pre- (PDAs), and laptop computers. formed component, it is slower than some Similar methods similar methods of multicomponent (that is, In-mold decoration (p.212) and insert two-shot) molding. molding (p.206). Surface Sustainability issues The key feature here is that it allows for Over-mold decoration requires an secondary “skins” to be applied over plastic additional stage of processing to apply moldings, so the surface is determined by decoration to a molded product which, of the material you choose as the covering. course, increases energy consumption. Types/complexity of shape However, the enhanced decorative surface Because of the secondary material, over- could help to extend the product’s lifespan mold decoration is best suited to flat through increased value perception. surfaces and those with a deep draw. As with any multimaterial component, Scale recycling can be problematic because The largest standard size is approximately of the need to separate materials. 12 by 12 inches. Further information Tolerances www.dow.com/inclosia Depend on the shrinkage of the various www.filminsertmoulding.com materials.

– Automated method of covering – Although over- plastic-molded components with a molding provides second soft, or decorative, material. benefits when it comes to surface – Cost-effective alternative to hand decoration, it is a assembly. two-step process, – Compatible with most engineering adding to unit price. thermoplastics and elastomers. – Can require trial and error when using untested materials.

LK016_P0194EDmakingIt2us.indd 215 16/09/2011 15:06 216 Complex: Metal Injection Molding (MIM) Metal Injection Molding (MIM)

A variation on standard injection the metal powders that are used as molding (which uses plastics; see the raw material, which need to be p.196), metal injection molding (MIM) particularly fine. is a relatively new way of producing MIM involves more processes complex shapes in large numbers from than plastic injection molding, because metals that have a high melting point, of the necessity of adding binders to such as tool steel and stainless steel the metal. The various companies that would not be suitable for high- involved in using this technology each pressure die-casting (see p.219). The have their own unique binder systems process is limited by the suitability of but typically the binders, which

Product engineering components [pen nib for scale only] Materials low-alloy steel and stainless steel Manufacturer Metal Injection Mouldings Ltd, part of PI Castings Country UK Date first produced in the UK in 1989

This range of small-scale, complex engineering components is typical of the type of products that are made using MIM. It offers us the chance to create precise, solid metal products from metals with high melting points that cannot easily be formed by casting. The strength and hardness of these components offers several advantages over other forms of metal production.

LK016_P0194EDmakingIt2us.indd 216 16/09/2011 15:06 Complex: Metal Injection Molding (MIM) 217

can account for 50 percent of the have been molded, the binder is no compound, are made from a variety of longer needed and is removed from materials, including wax and a range the metal particles. What is left is then of plastics. They are mixed in with sintered (see p.168), which shrinks the the metal powders to produce the component by about 20 percent. molding compound. Once the shapes

Volumes of production Typical products In order to justify the setup and tooling Surgical and dental tools, computer costs, high-volume production is components, automotive parts, casings needed—a minimum of 10,000 units. for electronics and consumer products Unit price vs. capital investment (cell phones, laptops, PDAs). High capital investment but a very low Similar methods unit price. Although die-casting in metal (p.219) is Speed possibly the closest to MIM in terms of The actual injection of material is similar production quantities and complexity to that of standard injection molding in of shape achievable, the key difference plastics (see p.196), but the sintering and between the processes is in the ability the removal of the binder add time and of MIM to work with metals with high expense to the process. melting points, such as low-alloy steels Surface and stainless steel. The process gives an excellent surface Sustainability issues finish on components and has the ability The additional processing and heating to produce fine detail. cycles significantly increase energy Types/complexity of shape consumption in comparison with Highly complex shapes similar to those traditional plastic injection molding. obtainable through standard plastic Compared to casting or metal machining, injection molding. These can also be there is practically no excess or scrap enhanced by the use of multicavity tooling. material, which helps to reduce waste and Scale energy use from secondary processing. MIM is currently capable of producing only The high-temperature nature of the small parts for use in larger products. materials means they are less likely Tolerances to feed into the recycling stream. The MIM process can achieve a general Further information 1 tolerance of ± /250 inch. www.mimparts.com Relevant materials www.pi-castings.co.uk MIM is economical for producing large www.mpif.org numbers of complex components with a range of surface finishes. It can be applied to a range of metals: bronze, stainless steel, low-alloy steels, tool steels, magnetic alloys, and alloys of low thermal expansion.

LK016_P0194EDmakingIt2us.indd 217 16/09/2011 15:06 218 Complex: Metal Injection Molding (MIM)

binder metal power

molten metal

electric motor

mold

heat

1 Binders are mixed with metal powders to produce the molding compound. This is fed into the injection-molding machine to form a “green” component.

binder

heat 2 After the shape has been molded, the binder is 3 What is left is sintered to weld the metal removed from the metal particles and discarded. particles together. This shrinks the component This step is achieved in a number of ways by about 20 percent. depending on the specific manufacturer.

– Can be used to form high- – Low overall part size. temperature alloys. – Compared with – Used to form complex shapes. standard injection molding in plastic – Cost-effective for large numbers. (see p.196), only a – No post finishing required. limited number of manufacturers can – Parts have exhibited good strength. offer MIM.

LK016_P0194EDmakingIt2us.indd 218 16/09/2011 15:06 Complex: High-Pressure Die-Casting 219 High-Pressure Die-Casting

High-pressure die-casting is one of the most economical methods of producing metal components with complex shapes. It is the process to use if you want to produce high volumes of intricate components. In this sense, it is similar to metal injection molding (MIM) (see p.216), but its main advantage over MIM is that it is suitable

Product Matchbox Lotus Europa Materials zinc Manufacturer Matchbox Country UK Date 1969

Die-cast metal toys are part of many people’s childhood memories. The ability of die-casting to create fine, complex details is well illustrated by the clearly legible text on the underside of my son’s toy car.

LK016_P0194EDmakingIt2us.indd 219 16/09/2011 15:06 220 Complex: High-Pressure Die-Casting

for metals with low melting points The pressure is maintained until the where no sintering is required. metal solidifies, at which point small The process involves molten ejector pins push the components metal being poured into a reservoir, out of the die. Just as in injection where a plunger forces the liquid, molding (see p.196), die-casting under high pressure, into a die cavity. molding dies are made in two halves.

Volumes of production Typical products High-pressure die-casting is strictly for Chassis for a range of electrical products high-volume production. such as PCs, cameras, DVD players, Unit price vs. capital investment furniture components, and wet-shaver Economical unit price is obtained by mass- handles. producing highly complex parts, which Similar methods eventually drives down the relative cost Investment casting (p.224) and sand of the expensive tooling that has to be casting (p.228), which allow the casting designed to withstand repeated injection of larger parts and require less capital of molten metal at high pressure. investment, but demand higher tolerances. Speed Gravity die-casting is a much older process Fast, although the removal of flash as a and is employed on a much smaller scale of separate process adds to the time. production than high-pressure die-casting. Surface Sustainability issues Excellent. The low melting points of the metals used Types/complexity of shape in high-pressure die-casting require lower Ideal for producing complex, open-walled temperatures and quicker cycles than parts in metal, especially those with thin some other processes, such as MIM, so the wall sections. Unlike investment casting process consumes less energy and releases (see p.224), high-pressure die-casting fewer emissions. However, excess flash requires draft angles. material after casting requires additional Scale trimming, which adds to energy use and Up to a maximum weight of approximately waste. At the end of their use, this can be 100 pounds for an aluminum component. reclaimed and recycled to reduce the use Tolerances of virgin metals. Reasonably high level of tolerance, but Further information shrinkage can sometimes be problematic. www.castmetalsfederation.com Relevant materials www.diecasting.org Metals with a low melting temperature, such as aluminum and zinc, which are by far the most commonly used materials. Others include brass and magnesium alloys.

LK016_P0194EDmakingIt2us.indd 220 16/09/2011 15:06 Complex: High-Pressure Die-Casting 221

mold

– Ideal for complex shapes. – Excellent surface finish. – Good dimensional accuracy. – Can allow for small sections and thin walls. – Excellent consistency between parts.

1 Molten metal is poured into a reservoir. – A fast process that requires minimal post-machining work.

plunger – The tooling is expensive, so the process is only suited to very high production volumes. 2 A plunger forces the liquid under high pressure into – Produces parts where flash is a die cavity. present. – Parts are not guaranteed to have high structural strength. pins

3 The pressure is maintained until the metal solidifies, at which time small ejector pins push the components out of the die.

LK016_P0194EDmakingIt2us.indd 221 16/09/2011 15:06 222 Complex: Ceramic Injection Molding (CIM) Ceramic Injection Molding (CIM)

Ceramics provide a hard, wear- and a key aspect of the molding process corrosion-resistant solution for many and is used because it has a lower engineering challenges that other melting point than the ceramic powder, materials are rarely able to meet. The which enables the two materials to be injection molding of ceramics allows separated at a later stage. A specially for complex shapes to be created made machine with greater corrosion in a process that borrows a great strength than traditional injection deal from the injection molding of molding machines is used to feed plastics. The technique is suitable the ceramic and binder mix into the for scales of production from one-off mold cavity. The corrosion strength is research prototypes to mass-produced required because of the abrasiveness of components for commercial products. the ceramic that is being molded. Ceramic injection molding (CIM) has Once the component has cooled been especially effective within the the mold is heated until it is just high medical field, to make components for enough to melt the binder material pacemakers and surgical instruments (but not the ceramic), causing it to that need to be micro-miniature, with evaporate and leave behind just exceptional tolerances, as well as the ceramic material. The finished being biocompatible. part can be sintered or undergo hot The most suitable type of ceramic isostatic pressing (HIP) in order to powder is chosen and mixed with a remove any stresses caused binder that allows the mixture to flow during molding and provide and become moldable. The binder is further strengthening.

Product Dental bracket used in braces [pencil sharpener is for scale] Materials 99 percent Alumina Manufacturer Small Precision Tools Country US Date 2010

The image illustrates a specific technology from Small Precision Tools that allows for molding ceramics such as dental brackets for braces at a micro scale.

LK016_P0194EDmakingIt2us.indd 222 16/09/2011 15:06 Complex: Ceramic Injection Molding (CIM) 223

Volumes of production Relevant materials The process allows for complex ceramic A range of ceramics, including parts to be produced in tens of thousands. oxide, silicon carbide, and aluminum Unit price vs. capital investment oxide. Producing molds means the initial setup Typical products cost is very high. Unit price is reduced CIM is particularly suited to small when the scale of production is increased. engineering components as ceramics Speed have exceptional resistance to wear Multiple components are produced in and corrosion, and chemicals, and are the same production run to optimize the biologically inert. This makes the process timescale: it can take many days for a part suitable for a range of parts, including to go through the various stages. dental implants. Surface Similar methods The nature of ceramic materials results in Injection molded plastics (p.196). a fine, stone matte surface. Sustainability Types/complexity of shape The main consideration in this multistage The types of shape have similar restrictions process is the use of heat during sintering to those of injection molded plastics, and the removal of the binder. where the main considerations should be Further information undercuts and the removal of components www.smallprecisiontools.com from the mold. Scale The component featured here from Small Precision Tools illustrates the tiny scale that this process is capable of. Components produced with this process are typically 1 1 measured in /25 or /12 inch, but components can be produced that would fit through the eye of a needle. Tolerances These vary depending on the type 1 of material but ± /5000 inch can be obtained.

– Complex and intricate parts that – Production of molds would otherwise be difficult or can be costly and even impossible to produce in time consuming. ceramics can be achieved.

LK016_P0223EDmakingIt2us.indd 223 16/09/2011 17:00 224 Complex: Investment Casting Investment Casting AKA Lost-Wax Casting

The name “investment casting” is itself forms a thick enough skin to hold taken from the idea that the process molten metal once the wax has been involves “investment” in a sacrificial melted away. Because the ceramic material, and it is characterized by mold is broken to reveal the finished its ability to produce highly complex object, it is possible to get away with shapes. The process has been around all kinds of undercuts and complex for thousands of years, with evidence shapes that would not be possible of its use by the ancient Egyptians. In to achieve with a rigid mold. essence, it involves a wax shape being The first stage involves the dipped into a ceramic liquid which manufacture of a die (usually made

wax pattern ceramic shell finished product

Product Spirit of Ecstasy car hood ornament Designer Charles Robinson Sykes Materials stainless steel Manufacturer Polycast Ltd Country UK Date 1911

These images illustrate three of the stages of investment casting for this highly recognizable figure. They also offer an excellent example of which method of production to choose when the fashion for ornate, decorative figurines returns to contemporary design.

LK016_P0194EDmakingIt2us.indd 224 16/09/2011 15:06 Complex: Investment Casting 225

from aluminum, but a polymer that resembles a kind of tree. This can also be appropriate), which is assembled runner is then dipped into repeatedly used to obtain the wax ceramic slurry, which is dried to form replica patterns. Multiple patterns are the hard ceramic skin. The dipping is produced that are assembled onto a repeated until sufficient layers have wax runner, which forms a structure been built up. The runner is then

Volumes of production Typical products Depending on size, it is possible to have Anything from sculptures and statues to several hundred small parts on a tree, gas turbines, marine shackles, jewelry, which can be cast in one pour. Larger and medical tools. One example with items are made with only one per tree. an extremely high profile is the “Spirit of Investment casting is a process that allows Ecstasy” that sits on the hoods of for small runs of below a hundred, as well Rolls-Royce cars. as runs of up to tens of thousands. Similar methods Unit price vs. capital investment High-pressure die-casting (p.219), The tooling is far cheaper than that sand casting (p.228), and centrifugal needed for high-pressure die-casting casting (p.161). (see p.219), which means lower capital Sustainability issues investment. Depending on the size of the After being smashed, the sacrificial final component, multiple castings can be ceramic can be collected and heated back produced on the same tree to increase into its slurry state to prevent waste and cost-effectiveness. to reduce further use of raw materials. Speed The process can be relatively energy Slow, requiring a number of steps to be intensive as obtaining the finished product completed for each component. involves stages of heating and processing. Surface Some foundries still use alcohol-based Good surface finish, but this is largely binders in the shell, which may pose a dependent on the surface of the pattern. threat to the environment when disposed Types/complexity of shape of. The main issue with any metal-casting Unlike in high-pressure die-casting, which technique is the heat used during requires draft angles, components made by the process. investment casting can be highly complex. Further information This is the main advantage the process has www.polycast.co.uk over other methods of forming. www.castmetalfederation.com Scale www.castingstechnology.com 1 Anything from /5 inch to about 20 inches www.pi-castings.co.uk long, or up to about 200 pounds. www.tms.org Tolerances www.maybrey.co.uk High. Relevant materials A wide variety of ferrous and nonferrous metals.

LK016_P0194EDmakingIt2us.indd 225 16/09/2011 15:06 226 Complex: Investment Casting

placed in an oven to melt the wax so metal to be poured into them. After that it can be poured out before the cooling, the ceramic can be broken ceramic is fired. The ceramic shells are away and each part may be removed now strong enough to allow molten from the tree inside.

1 After the initial manufacture of the die, 2 This image, featuring a different pattern, a wax pattern (on the right) is produced. shows a simple set of four components being dipped into the ceramic slurry.

3 A typical setup showing a number of wax 4 The ceramic shell filled with metal (with components on a simple runner before being a finished component held next to it for dipped into the slurry. comparison).

5 This is the stage where the dried ceramic 6 A final component shown with the original is removed and discarded revealing the final wax pattern. component.

LK016_P0194EDmakingIt2us.indd 226 16/09/2011 15:06 Complex: Investment Casting 227

wax runner wax pattern wax patterns

ceramic slurry

wax pattern

1 Wax patterns are made using 2 The individual wax patterns 3 The assembled runner is an aluminum die, which is reused are assembled onto a wax runner. dipped into ceramic slurry and to obtain the required number. dried to form the hard ceramic skin. The process is repeated until sufficient layers have built up. metal part fired ceramic

ceramic heat

melted wax 4 The runner is placed in an oven 5 Molten metal is poured into 6 The finished casting. to melt the wax so that it can be the fired ceramic shells. After poured out before the ceramic cooling, the ceramic is broken is fired. away and each metal part can be removed from the tree inside.

– Complex shapes with hollow cores – Involves several are possible. stages. – Weight savings due to the ability – Some foundries to form hollow cores. still use alcohol- based binders in the – A process for high accuracy. shell, which may – Eliminates post-process machining pose a threat to the operations. environment. – Freedom of design.

LK016_P0194EDmakingIt2us.indd 227 16/09/2011 15:06 228 Complex: Sand Casting Sand Casting 2 including CO silicate and shell casting

Of the many attributes of sand, one There are several derivatives of that stands out is the fact that it is a this basic principle. These include the refractory material. This means that use of patterns made from sacrificial it can withstand extremely high materials such as polystyrene foam, temperatures, and thus easily which evaporate when the metal is accommodate molten metals for poured in. Wooden patterns are used casting. There are various forms for small-batch work in foundries, of sand casting, the differences while the process can also be lying mainly in the quantity of the automated in a procedure that uses components that is required, but all aluminum patterns and a programmed rely on the very simple principle of compaction method. making a pattern (or duplicate) of Other methods include CO2 the finished part. This duplicate is silicate casting and shell casting. The embedded in a compacted mixture CO2 process is a recent development, of sand and clay and then removed, and it involves the sand being bonded leaving a cavity into which a molten with sodium silicate instead of clay. metal can be poured. Runners and This is converted into CO2 during risers are used in the sand to contain casting and it can provide greater a reservoir of excess molten material. accuracy because sodium silicate These are, essentially, holes in the makes a tougher mold. Shell casting sand: The runner allows metal to be uses fine-grained, very pure sand, poured in; the holds any excess coated in a thermosetting resin. This molten metal. This is a necessary means that the mold can be thin 3 precaution, because as molten metal walled (as little as /8 inch) but it is very solidifies, it shrinks, and at this stage strong. Shell casting offers several excess metal is drawn into the mold to advantages over conventional sand prevent voids in the casting. casting, such as greater tolerance and a smoother surface.

Product High Funk table legs Designer Olof Kolte Materials aluminum Manufacturer First produced by David Design Country Sweden Date 2001

The concept behind these table legs is that the design is sold without a tabletop, so that customers can buy legs to fit under the tabletop of their choice.

LK016_P0228EDmakingIt2us.indd 228 16/09/2011 17:00 Complex: Sand Casting 229

Volumes of production Relevant materials Sand casting can be used to make a single As a general rule, metals with low melting component or in large production runs. points, such as lead, zinc, tin, aluminum, Unit price vs. capital investment copper alloys, iron, and certain steels. For manual sand casting, the price is Typical products dependent on the cost of making a wooden Car engine blocks, cylinder heads, and pattern, with the unit price of the component turbine manifolds. being relatively cheap. Automated Similar methods processes are expensive, but will obviously Comparable, but more expensive, methods produce lower unit costs. include die-casting (p.219) and investment Speed casting (p.224), but on the whole sand Compared with high-pressure die-casting casting is capable of producing more (see p.219), this is a fairly time-consuming intricate shapes. process. Sustainability issues Surface Virgin sand is used for molding, and can Casting in sand gives a surface that is very be reused numerous times within the textured and that needs to be ground and process. However, heat and abrasion polished if a fine surface is required. Sand from the molten metal eventually cause casting using polystyrene leaves no parting damage to the sand, making it unsuitable lines and thus requires less finishing. for continued use, and it becomes waste. Shell casting can also provide a greater Fortunately some of this waste sand can surface finish. be recycled into noncasting applications, Types/complexity of shape but it is most commonly disposed of in By its nature sand is a fragile material landfills. It is estimated that only about to cast with, which means sand casting 15 percent of the several tons of foundry is best suited to quite simple shapes. sands generated annually are recycled. However, the large number of processes As with any metal-casting technique, that has developed allows for the the main issue is the heat used during production of complex shapes with varying the process. wall thicknesses and undercuts. Further information Scale www.icme.org.uk Compared with other forms of metal www.castingsdev.com casting, sand casting allows for the www.castingstechnology.com casting of very large components, but parts www.engineersedge.com 1 1 require a minimum of /8 to /5-inch wall- thicknesses, and they have a comparatively coarse finish. Tolerances As is the case with many other casting techniques, it is important to take shrinkage into account when considering the process. Various metals will have different shrinkage rates, but generally no more than approximately 2.5 percent. Shell casting provides a higher level of dimensional accuracy.

LK016_P0194EDmakingIt2us.indd 229 16/09/2011 15:06 230 Complex: Sand Casting

1 The cavity in the bottom mold is 2 Molten metal is poured into the 3 The part is lifted off with the top clearly visible as the top is lowered. runners. mold, ready for finishing.

pattern riser for runner riser

pattern pins for riser

box sand and clay pattern

1 First, the original pattern 2 Once the sand has been 3 The two halves of the sand (which includes the runners and compacted, the pattern is box are brought together and risers) is embedded in each of removed. secured with aligning pins. the two halves of the sand box.

molten metal

4 Molten metal is poured into the 5 Once the casting has cooled, 6 The finished part. runners, filling the mold cavity. the part is pulled from the sand.

– A low-cost process. – Can be labor- intensive, with high – Ease of operation. unit costs when – Many of the advanced forms used for small-batch allow highly intricate parts production. to be produced. – Parts may require – Flexible levels of production. a lot of finishing.

LK016_P0194EDmakingIt2us.indd 230 16/09/2011 15:06 Complex: Pressing Glass 231 Pressing Glass

Described as the closest thing to at a steady temperature to ensure “injection molding for glass,” the that the hot glass will not stick to pressed glass process makes it possible the molds. A gob of gummy, molten to mass-produce intricate glass glass is squashed between the two products with detailing on the inside, molds, with the amount of space left as well as the outside, of the shapes. between the male and female parts This is in marked contrast to glass determining the thickness of the blowing (see p.116), in which detailing final component. It is these two is restricted to the outside surface only. molds—which produce an inner and It is possible to trace the staggering outer imprint—that allow the shape boom in the mass-production of all to be controlled on two surfaces. In kinds of inexpensive glass products large-scale production, the machines back to the introduction of pressed typically work on a turntable with glass in 1827. a number of stations performing the The core of the process involves various stages of production, from male and female molds that are filling the mold with glass to the carefully preheated and maintained actual pressing.

Product lemon juicer Materials soda-lime glass Country China

Along with cheap ashtrays, this lemon juicer— bought from my local supermarket—illustrates the complex, thick, and chunky-walled forms that can be achieved by machine pressing glass in contrast to thinner, hollow, machine-blown glass products.

LK016_P0194EDmakingIt2us.indd 231 16/09/2011 15:06 232 Complex: Pressing Glass

The thick-walled, chunky edges that are its hallmark. As in the products that this process tends to case of other processes that generate produce are much more utilitarian products with a strong character, the than fine-quality cut glass, which particular “look” and “feel” of pressed goes through a secondary process of glass has led to some pieces becoming grinding to achieve the crisp, sharp collector’s items.

male mold

molten glass

female mold

1 The male and female molds are 2 The gob of gummy, molten glass is preheated and maintained at a steady squashed between the two molds. temperature to ensure that the hot glass The thickness of the final component is will not stick to them. determined by the amount of space left between the male and female molds.

– Definition can be – Its main disadvantage compared achieved on both with blown-glass products (see the inner and outer p.98) is that it does not permit surfaces. closed container shapes to be produced. – Allows for surface detailing that might – Not suitable for making thin-walled not be possible with sections. blowing. – Generally involves more expensive tooling than that used in the mass- production of blown glass.

LK016_P0194EDmakingIt2us.indd 232 16/09/2011 15:06 Complex: Pressing Glass 233

Volumes of production Tolerances Glass pressing is a term that can be applied Due to contraction and expansion of to a hand process, a semiautomated, or the material, glass pressing is able to an automated machine process. match the high tolerance of engineered Semiautomated production can be used components. However, a typical tolerance 1 for a minimum of 500 units, and is often is ± /25 inch. employed for sampling large production Relevant materials runs for fully automated production. Almost any type of glass. Unit price vs. capital investment Typical products In fully automated production, the unit Lemon juicers, railroad signal lamps, prices can be extremely low, but like lenses, street and display lighting, most high-volume production, it requires laboratory glass, glass ashtrays, sidewalk expensive tooling. lenses, wall blocks, marine and ship Speed lighting, aircraft and airport runway In an automated setup, and depending on lenses, and road and traffic signals. the component size, a single machine can Similar methods be set up to hold several molds at the same Cut glass can be used for fine-detailed time. This can result in huge production patterns, but this is really your best bet rates—some approaching 5,000 pieces for producing open glass shapes with the per hour. potential for decoration on both sides. Surface For plastic components, you might want Dimples, serrations, and diamond patterns to consider compression molding (p.174). are all achievable in pressed glass, Sustainability issues although the definition is less pronounced Glass is a renewable material that is than such patterns in cut glass. widely recyclable. Recycling it can reduce Types/complexity of shape waste and virgin material consumption, While blown glass (see p.116) lends itself and it retains its excellent clarity and well to rounded shapes, pressed glass is a appearance after reprocessing. However, lot more versatile because it allows for more its production and manufacture is less complex detailing and decoration. One of environmentally friendly as pressing the key design features to bear in mind is glass requires various stages of intense that it is not possible to have a closed shape heating, which consumes large quantities and, as in thermoforming (see p.64), the of energy. Some harmful air-polluting component must have a draft angle to compounds and particles are released allow for the mold to open at the end of during processing. production. Pressed glass is also more Further information suited to thick-walled hollow ware. www.nazeing-glass.com Scale www.glasspac.com Some semiautomated production allows for www.britglass.org.uk a maximum of about 24 inches in diameter. Larger pieces can be made, depending on both the volume of production and the manufacturer.

LK016_P0194EDmakingIt2us.indd 233 16/09/2011 15:06 234 Complex: Pressure-Assisted Slip Casting Pressure-Assisted Slip Casting with pressure-assisted drain casting

Pressure-assisted slip casting is a of the holes means that the capillary development of conventional ceramic action is reduced and replaced by the slip casting (see p.140). Compared with use of pressure (typically between 10 the traditional form, it offers several and 30 bar, depending on the size of manufacturing advantages that affect the product). This involves pumping the speed and complexity of the final the slip into the porous plastic mold. component. Conventional slip casting Under this pressure, the water seeps involves the use of plaster molds into out through naturally occurring which the ceramic “slip” is poured. capillary tubes in the mold. Once The “de-watering” of this slip is based dried, the form is taken out of the mold on a capillary action that draws water and any imperfections are cleaned off. from the slip into the plaster, leaving The product is then dried in fast dryers the clay to form a dry layer against the and sprayed with a glaze before firing. internal wall of the mold. This can be A project called Flexiform, led quite slow and the plaster molds have by Ceram Research in the UK, has a limited life. enhanced pressure-assisted slip In pressure-assisted slip casting, casting, coming up with a process it a more resilient material, with larger calls “pressure-assisted drain casting.” holes, is used for the mold. The size In this development, the conventional synthetic mold is replaced by a machinable plastic, which can be machined directly from the product designer’s original CAD drawing. This offers a number of further advantages, including cheaper tooling and the possibility of the mold being re-cut, which is not possible with the molds used for pressure-assisted slip casting.

Product bath from the Loo range Designer Marc Newson Materials ceramic Manufacturer Ideal Standard Country UK Date 2003

This bath is a typical example of the scale of casting that can be produced in ceramic.

LK016_P0194EDmakingIt2us.indd 234 16/09/2011 15:06 Complex: Pressure-Assisted Slip Casting 235

Volumes of production Tolerances Pressure-assisted slip casting molds As is the case with any fired piece, molds typically require volumes of approximately need to be made that take account of a 10,000 pieces to justify the use of the reduction in size once the product has plastic tooling. been fired. Unit price vs. capital investment Relevant materials Cost-effective unit parts, which are the Suited to most types of ceramic material. result of several factors, outlined above. Typical products In the Flexiform pressure-assisted Complex tableware, which can require drain-casting project, mold costs are four-part molds for teapots and coffee significantly reduced. pots with integral handles. Apart from its Speed large-scale use in sanitary ware, it is in the Conventional slip casting (p.140) can area of advanced ceramic technology that require anything up to an hour for casting, pressure-assisted slip casting is attracting de-molding, and drying. Pressure-assisted the strongest interest. slip castings can typically result in a Similar methods reduction in time of 30 percent. Ceramic slip casting (p.140) and Surface compression molding (p.174). Superior quality finish compared with Sustainability issues conventional slip casting, with reduced Water is used to aid the ceramic flow casting seams resulting in less felting than instead of the organic solvents or binders with the conventional method. that were previously used. This water can Types/complexity of shape be cleaned and recycled back into the From small and simple to large and complex process to reduce waste and consumption parts with undercuts. Anything, from of raw materials. Further material bathroom products to art objects and reductions are made through the increased dinnerware, can be made using this process. durability of the plastic molds, which can Just think of the U-bends on the underside withstand extensive use. of a toilet to glean an understanding of the Further information types of complexity possible. www.ceramfed.co.uk Scale www.cerameunie.net From small teacups to toilets and baths. www.ceram.com www.ideal-standard.co.uk

– The plastic mold allows higher – The molds add to the pressure to be used in the setup costs (however, production of large pieces. for drain casting, Flexiform molds – Plastic molds have a longer life greatly reduce the (approximately 10,000 casts) before tooling costs). they are thrown away. – Fewer molds are needed and less storage is required.

LK016_P0194EDmakingIt2us.indd 235 16/09/2011 15:06 236 Complex: Viscous Plastic Processing (VPP) Viscous Plastic Processing (VPP)

As the technology behind materials and production that is available. One of the manufacturing techniques progresses, problems in forming ceramics involves the previously barren spaces between the need to eliminate the inherent different families of materials are microstructural defects in ceramic bridged. Of all the material families, materials. These defects reduce the plastics make up the group that is the strength of the material, making it most versatile in terms of production techniques available. However, other materials, such as metals and ceramics, are all being explored to find new ways of mass-producing components using plastic-state forming techniques. This allows materials that have traditionally limited means of forming, including ceramics, to be formed using methods such as injection molding (see p.196). The material and the method of production go hand in hand in the sense that the properties of the materials dictate the complexity of

Product teacup from the Old Roses range Designer Harold Holdcroft Materials bone china ceramic Manufacturer Royal Doulton Country UK Date 1962

VPP technology was used to enhance the properties of bone china, so that these uniquely British teacups could be injection molded. A combination of design and the cost-effectiveness of this process means that 100 million cups have been sold since 1962.

LK016_P0194EDmakingIt2us.indd 236 16/09/2011 15:06 Complex: Viscous Plastic Processing (VPP) 237

brittle. Viscous plastic processing, The process involves ceramic powders or VPP, is a method of enhancing the being mixed with a viscous polymer properties of ceramic materials that under high pressure. This mixture eliminates these flaws, resulting in can then be used to form components a way of processing ceramics that is through a range of fabrication much more flexible and, to use the techniques, including extrusion technical term, “plastic” in its nature. (see p.96) and injection molding.

Volumes of production Tolerances Not applicable. Not applicable. Unit price vs. capital investment Relevant materials Not applicable. Any ceramic material. Speed Typical products Not applicable. Flat components, substrates for electrical Surface components, kiln furniture, springs, rods An excellent surface can be achieved, and tubes, strength in green-state cups, depending on the grain size of the body armor, and biomedical applications. ceramic powder. Similar methods Types/complexity of shape Not applicable. Because of the enhanced “viscous-elastic Sustainability issues behavior” of ceramics produced in this By enhancing the strength of the ceramic, manner, components have high strength thinner-walled parts can be produced to in their “green” state, which enables quite reduce material consumption and extend adventurous forms to be produced. The the lifespan of the product. This increased process also allows thinner wall sections to strength can also help to reduce possible be produced than is the case with standard defects during forming, which in turn ceramic materials, which ultimately to helps to minimize waste of materials higher strength parts with reduced weight. and additional processing. Any type of Scale fabrication used to form the ceramic– It is possible to create large products, polymer mixture requires extensive heat, but not in all dimensions. VPP is, in which is energy intensive. other words, capable of producing long, Further information extruded sections with wall thicknesses www.ceram.com of up to ¼ inch, or thin sheets.

– The process can be applied to a – Limited number of wide range of ceramic materials manufacturers. and offers materials with good “green” strength.

LK016_P0194EDmakingIt2us.indd 237 16/09/2011 15:06 7: Advanc

240 Inkjet Printing 242 Paper-Based Rapid Prototyping 244 Contour Crafting 246 Stereolithography (SLA) 250 Electroforming for Micro-Molds 252 Selective Laser Sintering (SLS) 255 Smart MandrelsTM for Filament Winding 257 Incremental Sheet-Metal Forming

LK016_P0238EDmakingIt2us.indd 238 16/09/2011 17:01 nced

Advanced and new technologies

The starting point for most of the processes featured in this section is that the information used to make the shape is supplied by a CAD file. This eliminates tooling costs, as do Smart MandrelsTM, also featured in this section (though these are not driven by CAD), and together they all provide a complete mind shift from existing rules of production. On this basis, the methods in this section point the way to future industrial production and hint at the fact that these new technologies will provoke the biggest change in the nature of mass-produced objects since the Industrial Revolution. It is a group of processes that includes the relatively familiar process of stereolithography, but also has some new technologies that put manufacturing into the hands of the consumer.

LK016_P0238EDmakingIt2us.indd 239 16/09/2011 17:01 240 Advanced: Inkjet Printing Inkjet Printing

Desktop printers have allowed anyone has turned a Canon i560 inkjet printer with a computer to turn a desk into into a machine for making food. a place where all sorts of things can Having replaced the ink cartridges, he happen. The seemingly humble printer prints edible liquids instead of CMYK may well be the hub of a revolution inks onto an edible starch-based paper. that will change the way we make In a move worthy of Willy Wonka (let’s objects. The day will soon come when not forget the edible sugary grass we will be able to download plans for and flowers in his chocolate factory), a product (a door handle, for example) Cantu has abducted a printing process and make it from our own desktop to create an entirely new concept in three-dimensional printer, which has how you order—and what you can been loaded with the appropriate raw eat—in a restaurant. materials, in the same way that you Possibly one of the most unusual load up your breadmaker last thing adaptations of this technology is at night so that you can enjoy a fresh one that has been developed by loaf in the morning. Before such three- various teams of scientists across the dimensional technology becomes a world, who use “modified” inkjet reality at a domestic level, however, printers to build up living tissue. “techies” are busy pushing the Based on the long-held knowledge envelope to discover new applications that, when placed next to each other, for this familiar object, with its cells will weld together, the process clanking robotics. involves tissue being built up, using Already, Homaro Cantu, a chef a thermo-reversible gel as a kind of based at Moto’s restaurant in Chicago, scaffolding over each cell. The team

Product edible menu Designer Homaro Cantu Materials vegetable-based dyes on edible paper Manufacturer Moto Restaurant, Chicago Country USA Date 2003

This printed edible menu provides an example of an interesting crossover between the food and the production industry and shows that even on a “techno” level food is providing a rich source of experiments.

LK016_P0238EDmakingIt2us.indd 240 16/09/2011 15:11 Advanced: Inkjet Printing 241

that developed this, from the Medical action. This gel is interesting in itself, University of South Carolina, uses since it is designed to change instantly the thermo-reversible gel as a way from liquid to gel (and back again) to support the cells as they are being in response to a stimulus such as a distributed through the “printing” change in temperature.

Volumes of production of liquid and solid materials. The examples From one-offs to small batch production. mentioned above give you some idea of Unit price vs. capital investment the potential. Two-dimensional printers are within most Typical products people’s budget, so you can take one apart The beauty with this process is that the and play with it at will, substituting the examples mentioned above are currently inks with anything you care to try. a sort of DIY production, based on groups Speed of people tinkering with technology and Depends on what you want to do, but machines to give them new functions. typically this is still a fairly slow process. The two contrasting examples illustrate Surface that there is no such thing as a typical When making three-dimensional objects product for this hybrid technology. from standard production materials, the Similar methods surface may have a ribbed texture as witness Contour crafting (p.244), selective laser to the way the material has been laid down. sintering (SLS) (p.252), and electroforming Types/complexity of shape for micro-molds (p.250). Highly complex shapes, restricted only Sustainability issues by what you draw on your computer. The edible outcome of inkjet printing Scale shown here is a particularly poetic The team from the Medical University of example of how waste could be South Carolina has demonstrated the highly eliminated—sheets can simply be eaten! controlled, cell-by-cell scale that is possible. Although experimentation is encouraged, Tolerances care should be taken not to create too The production of three-dimensional living much waste or break too many printers tissue demonstrates the fine tolerances through testing materials. In conventional that are achievable. ink-based printing the main issues are Relevant materials recycling and reuse of the cartridges. Again, the machine is there to be explored, Further information though you will need a basic combination www.motorestaurant.com

– Allows for any shape generated – Still in its infancy. on a computer to be turned into a three-dimensional object. – Slow. – Open to experimentation.

LK016_P0238EDmakingIt2us.indd 241 16/09/2011 15:11 242 Advanced: Paper-Based Rapid Prototyping Paper-Based Rapid Prototyping Layered paper

The machine used for paper-based takes the drawing or scan and breaks rapid prototyping makes the common it up into layers the same thickness inkjet printer look prehistoric and as the paper. When the information is allows users to do extraordinary sent to the printer, it cuts each slice things. It is able to take a humble, of paper to shape and layers them everyday sheet of 8½ x 11 inches one on top of the other using a water- and create an extremely detailed based adhesive. The layering takes and intricate model of virtually any several hours, but the end result is an shape imaginable. incredibly precise 3-D shape made It allows you to take a drawing up of hundreds of pieces of paper or scan from your computer and print layered together. it out into a 3-D physical object made Because of the flexibility of solely out of sheets of paper. To do paper, a working, live hinge can be this the machine uses software that produced in one piece—something that cannot be achieved with many plastic-based alternatives—which means you get a more accurate prototype that is as close as possible to the real thing. As only paper and a water- based adhesive are used, prototypes can be recycled, which makes this the most eco-friendly process on the market. What’s more, recycled paper can be used in the first instance, with excellent results.

Product Cell phone cover Materials Photocopier paper Manufacturer Mcor Technologies Ltd Country UK Date Unknown

These cell-phone covers show the level of finish and detail that is achievable with this paper-based rapid prototyping process.

LK016_P0238EDmakingIt2us.indd 242 16/09/2011 15:11 Advanced: Paper-Based Rapid Prototyping 243

Volumes of production Typical products As a form of rapid prototyping the process is The process is being developed for use in ideal for low-volume production. the medical industry, to reproduce X-rays Unit price vs. capital investment in a physical form to help surgeons to The process is said to be up to 50 times plan ahead of operations, and in dentistry cheaper than those used for plastics: to enable orthodontists to create molds paper costs very little and is available of patients’ teeth much more quickly almost anywhere. than can be done using plaster. It is Speed also expected that the process will be The cell-phone covers shown here were introduced for engineering, architectural, built in 5–10 hours. and industrial design programs, for use Surface by students as a cheaper alternative to The surface has the consistency of wood traditional plastic rapid prototyping. and requires minimal finishing. The Z-axis It is also a popular choice for architectural 1 resolution is /250 inch. models, and as rapid tooling for molds Types/complexity of shape in processes such as vacuum forming, The process is suited to most complex and also investment and sand casting. shapes that can be produced by stereo- Similar methods lithography. The exceptions are thin, Molding paper pulp (p.149), pulp paper spindly shapes. composite from Sodra Paper Labs (p.78). Scale Sustainability The process is based on standard 8½ x 11 Paper is a rapidly renewable resource, and inch paper and a maximum stack height of is also widely recycled. No toxic fumes are 6 inches. released during processing, as they are Tolerances with some plastic rapid prototyping, and 1 Currently /250 inch on the XY-axis and components can be produced in a short 1 percent on the Z-axis. timescale to make effective use of Relevant materials energy consumption. Standard photocopier paper; Mcor Further information Technologies recommend low-grade paper www.mcortechnologies.com with a low fiber content for best results.

– Quick production time. – Currently limited to letter-size paper. – Paper is cheap compared to alternative plastic resins and is readily available. – More environmentally friendly than processes that use plastics.

LK016_P0238EDmakingIt2us.indd 243 16/09/2011 15:11 244 Advanced: Contour Crafting Contour Crafting

This is a process that has the potential industry has been advancing steadily to revolutionize the construction ever since the Industrial Revolution. industry. Dr. Behrokh Khoshnevis, In comparison, developments in the of the University of Southern construction industry have been California, has invented a machine meager during the same period. that “prints” houses. As he points out, However, this is something that the automation of the manufacturing Dr. Khoshnevis plans to change with a process he calls “contour crafting,” an advanced form of spraying concrete. Planned to be commercially available in 2008, the machines that are at the heart of this technology use a method of depositing concrete that is similar to that used in inkjet printers (see p.240) and extrusion (p.96). In this case, however, the technology is on a much larger scale, and it includes the ability of the “printing” head to move in six axes and build up material in layers, based on CAD drawings rather than on two-dimensional graphics. The “printing” nozzles, which are suspended from an overhanging carriage, deposit quick-drying concrete that is shaped by an integral trowel using a cylinder-and-piston system. Product contour-crafted prototypes A secondary feature of contour crafting and CAD design drawing is that the system allows utilities, such Designer developed by Dr. Behrokh as conduits for electricity, plumbing, Khoshnevis Materials concrete and air-conditioning, to be embedded Manufacturer Dr. Khoshnevis, under National into the process. Science Foundation and Office of Naval Research Country USA

These samples, though not on the scale of a building, illustrate the types of forms that can be created through contour crafting. Above is an example of the sort of CAD design that will drive the spraying process.

LK016_P0238EDmakingIt2us.indd 244 16/09/2011 15:11 Advanced: Contour Crafting 245

Volumes of production Relevant materials The key feature of contour crafting is that it Cement, with additives such as fiber, is an automated building method, however sand, and gravel. buildings can, of course, only be erected Typical products one at a time. This is a process that is offering Unit price vs. capital investment the building industry a new way to Allowing for the fact that multiple houses construct permanent houses, buildings, can be built using a single machine, Dr. and complexes, as well as temporary Khoshnevis estimates the cost of building emergency shelters. an average-sized American house at between Similar methods a fifth and a quarter of the current cost of On this scale, the process is unique. building a house by conventional means. The CAD-based system makes it Speed similar to many smaller scale rapid- Construction using this process can build a prototyping processes (see, for example, 2,000 square-foot house, including electricity stereolithography [SLA] p.246). and plumbing, in less than 24 hours. Sustainability issues Surface With its high-speed “printing” system, The use of the various types of trowel contour crafting could dramatically reduce produces a good concrete surface, one that construction times and therefore energy requires no preparation before painting. A consumption in comparison to traditional painting system may even be incorporated building techniques. There is no wasted or within the contour crafting process itself. excess material as the concrete is built up Types/complexity of shape accurately in layers to the exact contours The shape is limited only by the CAD drawing of the structure. and the normal physical forces that apply Further information to buildings, though even shapes such as www.contourcrafting.org arches can be extruded through the nozzle. www.freeformconstruction.co.uk Scale Dr. Khoshnevis suggests that this method can be used for anything from a small house to a high-rise structure. Tolerances The nozzle assembly that can move in six axes allows for very high tolerances on a large scale.

– Allows for rapid construction. – Still in its infancy. – Plans and designs can be easily altered because they are CAD- driven. – It is possible to use local materials as reinforcement for the cement. – Cost-effective. – Automated process.

LK016_P0238EDmakingIt2us.indd 245 16/09/2011 15:11 246 Advanced: Stereolithography (SLA) Stereolithography (SLA)

Stereolithography (SLA) is one of and turning successive thin layers the best known methods of rapid of the liquid into solid. The solid part prototyping. Driven by a CAD file, remains below the surface of the resin components are produced by a laser, throughout the process, because it which scans a bath of photosensitive is seated on a bed that is lowered resin, building the components layer gradually, allowing the component by layer. The ultraviolet laser beam is to be built up in layers. focused onto the surface of the liquid, All rapid prototyping tracing the cross-section of the part technologies give a geometrical freedom that no other processes do. SLA is typical in that it allows for the

Product Black Honey bowl Designer Arik Levy Materials epoxy Manufacturer Materialise Country The Netherlands Date 2005

This beautiful, open-cell structure is an excellent example of the highly intricate and complex forms that can be built up using this process.

LK016_P0238EDmakingIt2us.indd 246 16/09/2011 15:11 Advanced: Stereolithography (SLA) 247

testing of components before entering materials, although not to as many as into mass-production. Your choice of vacuum casting. (This is a method of process is dependent on the geometry producing small batches of identical of the part, the surface quality components that are generally used required, or the material that you want for prototyping or modelmaking. It to use. Selective laser sintering (SLS) involves producing an original master (see p.252), for example, cannot match that is cast into a silicone mold. The SLA for quality. mold is subsequently filled with plastic SLA is an accurate process, resins. A vacuum is applied and the although not the most accurate, resulting parts are very accurate, with and it can be applied to a range of fine detail and thin wall sections.)

beam laser beam controller

photosensitive resin

CAD image

adjustable bed

1 Driven by a CAD file, components are produced 2 The ultraviolet laser beam is focused onto the layer by layer by a laser scanning a bath of surface of the liquid, tracing the cross-section of photosensitive resin. the part and turning successive thin layers of the liquid into solid. The part gradually sinks below the surface as it is lowered in a bed, allowing the whole structure to be built up.

LK016_P0238EDmakingIt2us.indd 247 16/09/2011 15:11 248 Advanced: Stereolithography (SLA)

1 This image, of designer Patrick Jouin’s 2 The finished chair is seen this time with a CI chair, shows the finished product being white block that acts as an internal support for raised from the liquid polymer. During actual the seat during the forming process, without production the only part visible is the very top which the chair would collapse. edge of the chair as it is formed by the laser.

3 The completed chair before 4 The finished chair in all its translucent, ghostlike glory. removal of the support block.

– Unlimited geometric – High unit costs. freedom. – Only photosensitive resins can be – Good surface finish. used. – No intermediate – Inaccuracy in two directions. steps between the CAD model and – Often needs support structures. finished object. – Not as rapid as many other prototyping processes.

LK016_P0238EDmakingIt2us.indd 248 16/09/2011 15:11 Advanced: Stereolithography (SLA) 249

Volumes of production Tolerances Due to the time it takes to build up a Height is the least accurate dimension, product, SLA is strictly limited to low- because of the increased number of passes volume production. that the laser has to make, but tolerance is 1 Unit price vs. capital investment generally ±0.1 percent plus /25 inch. No tooling, and, even with a fairly high unit Relevant materials price, it is still the most cost-effective way Ceramic, plastic, or rubber can be used. of making prototypes. More commonly, engineering polymers Speed such as acrylonitrile butadiene styrene Dependent on a number of factors, including (ABS), polypropylene, and acrylic mimics the volume of the part, the material used, are used. and the fineness of the step that is set Typical products by the operator. Another factor is the The word “typical” has no application orientation of the component: If, for example, here, since you can make anything that a beverage can is made lying down, the you want. process is quicker, although less accurate, Similar methods than when it is made standing up, which Vacuum casting (see above), selective requires more passes with the laser. laser sintering (SLS) (p.252), and inkjet Surface technology (p.240). The “stepping effect” as a result of the Sustainability issues layering can be controlled by the thickness Stereolithography requires a UV laser of the step. Also, shallow gradients will to cure the resin, and this is very energy produce lines similar to contour lines on intensive as cycle times can be quite maps. Steep gradients and vertical walls slow depending on the complexity of the will have smoother surfaces, but in both part. The additional support structures cases the part may need sand blasting. required for the majority of moldings Types/complexity of shape can increase material consumption and Anything that can be drawn on a computer. waste. However, the uncured liquid resin Scale is washed off the finished part and can Standard machines can allow for a 20 by be recycled back into the process to help 20 by 24-inch building area. For anything minimize material use. As with all rapid bigger than this the components must production methods, tooling is eliminated be made in several sections and joined and in the future local production will together. However, some companies make eliminate transportation costs. their own machines, producing components Further information several feet long. www.crdm.co.uk www.materialise.com www.freedomofcreation.com

LK016_P0238EDmakingIt2us.indd 249 16/09/2011 15:11 250 Advanced: Electroforming for Micro-Molds Electroforming for Micro-Molds

Swiss company Mimotec has developed Micro-molding is closer to the the process of electroforming (see seriously minuscule nano-end of the p.164) to the extent that it can be scale, rather than just small-scale used to make micro-molds. Before molding, with parts being produced describing the Mimotec process itself, that can weigh as little as a few however, I need to make it clear that thousandths of an ounce with details micro-molding is not the same as that measure only a few microns thick. “miniature” injection molding. Although the principle behind micro-molding is reasonably conventional, the methods used to produce the molds are rather fascinating. Micro-molds can be made by a number of different methods, including a micro-milling technique (where material is cut away). Mimotec, however, has harnessed the fine detailing achievable with electroforming to produce the most minute of molds. The Mimotec process starts with an unpolymerized layer of photo resist deposited on a glass plate. This is then exposed to ultraviolet light through a mask of the final shape, which causes the exposed resist to polymerize, leaving the nonexposed area to be washed away. The remaining part is coated with gold followed by a further layer of resist. The part is built up in this way to produce a more complex part, which acts as the molding block and incorporates holes through which Product micro-mold Manufacturer Mimotec plastic for the component can be Country Switzerland

A close-up image of the finished part (top) shows the scale achievable, as does the mold (beneath) that has a pinion cavity of only 1/425 inch and a micro-inscription on the side. The plate (as the presence of the needle demonstrates) is only 1/5 by 3/8 inch, and 1/20 inch thick.

LK016_P0238EDmakingIt2us.indd 250 16/09/2011 15:11 Advanced: Electroforming for Micro-Molds 251

injected. This process is just one of excellent demonstration of the ever- many new methods of forming advancing research that is going on nano-scale components, and it is an in this field of production engineering.

Volumes of production Relevant materials Production runs of up to tens of thousands The micro-mold itself is made from gold of components are possible using this type with a nickel alloy coating. The molded of micro-mold. parts are generally made from polyacetals Unit price vs. capital investment (POM) and acetal resins. The CAD-driven nature of this process Typical products means that the setup costs are low. As you might expect, the micro-molds Speed are used to produce very small parts for It takes about seven hours to deposit biomedical devices and electronics, a layer 100 microns thick, but several watchmaking, and telecommunications thousand micro-molds can be made components. concurrently on a single glass plate. Similar methods Surface Wire EDM (p.44) and micro-milling It is possible to achieve high levels of detail techniques. and a fine finish on micro-molds made in Sustainability issues this way. Although the process can be very slow, the Types/complexity of shape molds produced using this method require It is not possible to make molds that are no heat treatment or further processing capable of making shapes with tapered, such as polishing, which can significantly or anything other than straight vertical, reduce energy consumption. As the sides. Steps can be produced but require component is built up in layers to the longer timings. exact contours of the design, no cutting or Scale machining away of materials is necessary, It is possible to create blocks of as little so the process makes very efficient use of as 100 cubic microns, with embedded resources and eliminates waste. The molds channels 30 microns wide. The largest have an above-average life expectancy to parts are 4 by 2 inches. ensure continuous use. Tolerances Further information ± 2 microns. www.mimotec.ch

– Capable of extreme – Making micro-molds in this way precision. is a fairly slow process. – Low setup costs – Restrictions in current technology for electroforming mean that only nickel and phospho- make it good for nickel alloys can be used for the prototyping. micro-molds.

LK016_P0238EDmakingIt2us.indd 251 16/09/2011 15:11 252 Advanced: Selective Laser Sintering (SLS) Selective Laser Sintering (SLS) with selective laser melting (SLM)

Innovation in production techniques is an adapted (and refined) form of has recently been dominated by sintering in which a laser is used to advances in rapid prototyping. solidify precise areas in a powder Designers are increasingly able to block in order to produce lightweight exploit the potential to make unique components. As in any sintering objects directly from a CAD file on a process, a powdered material (in the computer and selective laser sintering case of the implants illustrated here, (SLS) is just one of the significant a metal) acts as the starting point. developments, opening up a world A laser, driven by a CAD file, is fired of rapid prototyping. repeatedly into the powder, fusing the Sintering (see p.168) is a particles together layer by layer until significant part of the field of powder the specific component is built up. The metallurgy and it can be used in process is also known as selective laser a number of different production melting (SLM) for obvious reasons. methods. Selective laser sintering This, however, is only the beginning for the team at Renishaw PLC in the UK who use the technology beam to produce a type of microscopic controller scaffolding. They are able to exploit the design potential of a CAD file CAD-driven to produce components with a tiny, pulsed laser beam but complex, lattice-like structure. This results in forms that are made up mainly of air, like a sponge. The advantage of this type of microscaffolding is that it enables components to be produced in metals

metal powder with a very high strength-to-weight ratio—the density of stainless steel parts, for instance, can be reduced by as much as 90 percent compared powder reservoir adjustable bed with conventional processes.

A laser is fired repeatedly into a particulate material, fusing the particles together at the point of impact until the specific component is built up, layer by layer.

LK016_P0238EDmakingIt2us.indd 252 16/09/2011 15:11 Advanced: Selective Laser Sintering (SLS) 253

Product sample of a hierarchical structure produced using SLM technology Designer not applicable Materials stainless steel Manufacturer Renishaw PLC Country UK Date 2005

This structure, only 11/8 inch high, was produced to demonstrate the small scale of work that is achievable using selective laser melting (SLM) technology.

– Allows lightweight components – High unit costs. with high strength to be produced. – Easily customizable. – Can be used with a range of metals and other materials. – Fully automated system.

LK016_P0238EDmakingIt2us.indd 253 16/09/2011 15:11 254 Advanced: Selective Laser Sintering (SLS)

Volumes of production Typical products Each component is made individually. SLS, principally a form of rapid prototyping, Unit price vs. capital investment was initially used to test models before No tooling, but the unit price is high production. However, designers are because parts are individually made. pushing the technology toward production Speed of finished products. This particular Although it is anticipated that selective technology can be used to make anything laser sintering will eventually be taken up from jewelry and heat sinks for computers more widely for end production, it is still to medical and dentistry implants. a fairly slow and low-volume process Similar methods best suited to prototyping. Other CAD-driven technologies including Surface deposition prototyping (contour crafting, Components currently show a surface p.244, for example), stereolithography (SLA) roughness of 20–30 microns—very little, (p.246), and three-dimensional printing in other words. (such as adapted inkjet printing, p.240). Types/complexity of shape Sustainability issues Limited only by the CAD technology that To make efficient use of materials and drives it, the microstructure of the Mining eliminate waste, components are built up and Chemical Products components in layers to the exact contours of the design demonstrates that this is about as good thus eliminating secondary cutting or as it gets when it comes to creating manufacture. The levels of complexity that complex shapes. can be achieved in these microstructures Scale also allow for reductions in material use It is possible to achieve very fine details, and therefore weight. Because of the such as thin vertical walls with a thickness minute size of the components being 1 of as little as /250 inch, while the overall size made, several parts can be produced of parts is limited by the size of the powder within the powder bed to increase block reservoir that the machine can hold. productivity and energy efficiency. Unlike Tolerances stereolithography, SLS does not require a Extremely high. support structure so waste and material Relevant materials consumption is lower. As with all rapid Any particulate material used in powder production methods, tooling is eliminated metallurgy: metals, including steel and and in the future local production will titanium, and plastics. eliminate transportation costs. Further information www.renishaw.com

LK016_P0238EDmakingIt2us.indd 254 16/09/2011 15:11 Advanced: Smart MandrelsTM for Filament Winding 255 Smart MandrelsTM for Filament Winding

Shape-memory alloys and polymers In the first case, a single-shape memory are big news in the world of materials. mandrel can be formed into a specific Characterized by their ability to be shape, used to produce the relevant “programmed” to a particular shape, components, and then reheated, once heated and softened they can be re-formed, and reused to form a new bent out of this shape and re-formed shaped mandrel for an entirely different into a new shape, which is retained component. The second application is once the material has cooled. The in the forming of a complex mandrel, clever part is that when reheated, one that might otherwise have been the part will return to its original impossible to remove from inside “programmed” shape. the final component because of The US-based company, undercuts, and so on. Cornerstone Research Group, one Filament winding using of the major world players in shape- Smart MandrelsTM means that the memory technology, has exploited filament can be wound around the such materials to develop a patented mandrel, which is subsequently tooling system, Smart MandrelsTM, for heated, softened, and returned to its producing mandrels for the process “programmed” straight tube shape. of filament winding (see p.158). This allows the completed filament This system can be used in two ways. winding to be easily removed.

1 Winding onto 2 The Smart the purple Smart MandrelTM is heated MandrelTM begins. and softened for easy removal from the completed winding.

LK016_P0238EDmakingIt2us.indd 255 16/09/2011 15:11 256 Advanced: Smart MandrelsTM for Filament Winding

Volumes of production Scale For now, small runs and prototyping only, Machines can be built to produce filament but this recently developed process will be windings to a massive scale. The only equally suitable for large-scale production, limitations on scale will be the size at which since the mandrels are durable and can be the shape-memory alloys and polymers used to make many parts. can be made and remain effective. Unit price vs. capital investment Tolerances Smart MandrelsTM offer big savings for low Not the kind of process that is suitable production runs. This is because there is when high tolerances are required. no need for expensive, multipiece tooling, Relevant materials with the price staying at the same level for Any thermoset plastic material, and glass large production runs. or carbon fiber. Speed Typical products Cycle times are several minutes for each Aeronautical components, tanks, rockets, part, but it is significantly quicker than and housings. conventional filament winding with rigid Similar methods mandrels (see p.158) because there is no Pultrusion (p.99), and contact molding need to assemble and disassemble the (hand or spray lay-up) (p.152). mandrel for each part. Sustainability issues Surface Filament winding is largely automated No post finishing necessary, but the parts so electrical energy is required to power do have the distinctive “look” of filament- the motors. The high speeds at which wound products. the machines can operate help to make Types/complexity of shape efficient use of this energy through The main advantage with Smart MandrelsTM high-volume production. The high is that they allow for more complex forms strength-to-weight ratio also offers to be produced using the filament-winding significant weight savings. process. These can incorporate undercuts Further information and returns that would normally be www.crgrp.net impossible to produce, because the mandrel could not be removed from the component.

– Capable of producing highly – All parts have the versatile shapes. distinctive “look” of filament-wound – Reduced labor costs due to the ease products. with which the mandrel can be removed. – Limited availability because it is a – Reusable and adaptable tooling. patented process. – Simple to remove mandrel from component.

LK016_P0238EDmakingIt2us.indd 256 16/09/2011 15:11 Advanced: Incremental Sheet-Metal Forming 257 Incremental Sheet-Metal Forming

One of the major research areas in tooling. It is a term used to describe manufacturing at the moment is in a number of methods of sheet forming the arena of “industrial craft,” a term that employ a generic, single-point tool that embraces a range of technologies that presses against a metal sheet in that allow for a very flexible approach three axes (the work piece is held to mass-production by eliminating in a clamp), depressing it into a shape the need for specialized tooling. based on a path that is supplied by Incremental sheet-metal forming has a CAD file. the potential to revolutionize sheet- The process has been in use for metal forming, making it available 15 years, but its potential is still not for low volumes of production for widely adopted in industry, chiefly customized parts. as a result of the difficulty in assuring In essence, incremental sheet- metal forming is a type of rapid prototyping for sheet metal using a mobile indentor, so that almost any three-dimensional shell-shape can be made, without the need for specialized

Product sample of incrementally formed sheet Materials stainless steel Manufacturer sample produced by Institute for Manufacturing, Department of Engineering, University of Cambridge Country UK Date 2006

Researchers Julian Allwood and Kathryn Jackson of Cambridge University are two of the many researchers internationally who are looking at ways of developing the process for wider industrial use. The stepping seen in this sample illustrates the path of the tool as it traces across the metal sheet, slowly pushing it into shape.

LK016_P0238EDmakingIt2us.indd 257 16/09/2011 15:11 258 Advanced: Incremental Sheet-Metal Forming

geometrical precision in the formed part. However, Toyota has explored the process for forming parts for prototyping cars, using a one-sided die in order to gain more control. There are a number of researchers exploring different variations of the process, some of whom are using two indentor tools at the same time, on either side of the work piece. Negative and positive dies can also be employed to give greater control of geometrical accuracy and surface finish.

This close-up image shows the single-point tool poised over the clamped sheet of metal, which is about to be formed into shape.

CAD image

1 The shape of the component 2 The metal sheet is fixed into 3 The final component is drawn as a CAD file. a clamp and a single-point tool is removed. presses the sheet into shape.

– The main advantage of this process – Limited availability. lies in its ability to produce complex forms using a generic tool, which – Still in its infancy. ultimately means that there are no tooling or setup costs for one-off or small-production volumes.

LK016_P0238EDmakingIt2us.indd 258 16/09/2011 15:11 Advanced: Incremental Sheet-Metal Forming 259

Volumes of production model. This can be improved, but The process of incremental sheet-metal it involves trial and error. Accuracy is forming is increasingly well known and is obviously much greater if a die is used. attractive because it offers the possibility Relevant materials of economic production of small batches. A wide range of materials, including a It has been used for manufacturing prototype selection of aluminum and steel alloys, products, including a prototype car made stainless steel, pure titanium, brass, by Toyota. Other applications such as and copper. dental prosthetics, where each product Typical products must be unique, are also emerging. Several applications exploit the potential Unit price vs. capital investment of this process for one-off production, The obvious advantage of this process including the manufacture and repair of lies in the fact that it allows low-volume car body panels, tailored medical devices production with extremely low tooling and prosthetics, and architectural panels. and setup costs. Similar methods Speed Incremental sheet-metal forming has Typical feed-rates can be up to 2 inches its roots in metal spinning (p.56), but per second, and a typical part will obviously has far greater advantages in take between 20 minutes and an hour, terms of rapid prototyping and flexible depending on the surface quality required. manufacturing. Another closely linked Surface process is press forming (see metal Depends on the step size between cutting, p.59). successive passes of the tool. A step size Sustainability issues 1 of around /250 inch per pass gives an A-class The process eliminates the need for surface, as rated by a car body maker. specialized tooling for each component The surface can also be enhanced by the produced, and dramatically reduces use of molds. material use in mold manufacture and Types/complexity of shape subsequent energy use. Faulty sheets Depends on whether or not a die is used, can simply be reworked rather than but the parts will always be shell-shaped— reprocessed or scrapped, which further although, in the near future, machines will minimizes energy use and also allows be built with upper and lower indentor for easy modification of pre-formed tools to get around this. parts. In terms of batch production and Scale prototyping, processing speeds and While typical components are energy use can be more efficient than approximately ¼–½ inch square with an in competitive techniques. 1 average thickness of /25 inch, researchers Further information in Japan are capable of forming parts that www.ifm.eng.cam.ac.uk/sustainability/ range from a fraction of an inch in length up projects to sheets that are 6½ feet long. Tolerances Depend on whether or not a die is used. First-time geometric accuracy can be poor 1 1 (out by /12– /5 inch), even if the tool path is only creating simple contours from a CAD

LK016_P0238EDmakingIt2us.indd 259 16/09/2011 15:11 Finishi n Techni q

In his visionary book The Materials of Invention, Ezio Manzini defines the surface of objects as “the location of the points where an object’s material ends and the surrounding ambient begins.” The surface of a product can often be the simplest and most viable location for invention. In 2010 the appliance manufacturer Miele launched a special-edition vacuum cleaner that was covered in a peachy, flocked surface. It transformed a product that would have been made with a very ordinary high-gloss plastic into a completely different visual and tactile surface. Including techniques such as painting, plating, and covering, this section presents many of the standard and often widely available processing methods that fit into the areas of practical and decorative coatings. It also includes a snapshot of some of the increasing number of high-tech and smart coatings that are adding a new kind of functionality to products.

LK016_P0260EDmakingIt2us.indd 260 16/09/2011 15:17 i n g i ques

262 Sublimation Dye Printing 272 Case Hardening Vacuum Metalizing High-Temperature Coatings 263 Flocking 273 Thick-Film Metalizing Acid Etching Protective Coatings 264 274 Shot Peening Screen Printing Plasma-Arc Spraying 265 Electropolishing 275 Galvanizing Tampo Printing Deburring 266 Suede Coating 276 Chemical Polishing Hot Foil Blocking Vapor Metalizing 267 Over-Molding 277 Decalization Sandblasting Pickling 268 i-SD System 278 Nonstick Coating (organic) In-Mold Decoration Nonstick Coating (inorganic) 269 Self-healing Coating 279 Chrome Plating Liquid-Repellent Coatings Anodizing 270 Ceramic Coating 280 Shrink-Wrap Sleeve Powder Coating Dip Coating 271 Phosphate Coatings 281 Ceramic Glazing Thermal Spray Vitreous Enameling

LK016_P0260EDmakingIt2us.indd 261 16/09/2011 15:17 262 Finishing Techniques: Decorative Decorative Sublimation Vacuum Dye Printing Metalizing

Sublimation dye printing is used exclusively to It’s not exactly the real thing but if you need to decorate premolded, three-dimensional plastic give a metal effect on plastic components this is products. Colors, patterns, and graphics, like those the process for you. It is diffi cult to chrome-plate seen on Massimo Gardone and Luca Nichetto’s plastics using conventional electroplating, but Around the Roses tables (above), can be applied vacuum metalizing is a cost-effective and widely but the process offers no protection; instead it used method of achieving similar results. provides decoration that does not diminish even During the vacuum metalizing process, with scratches. Unlike silk-screening or painting, aluminum is evaporated in a vacuum chamber, it is able to produce a full spectrum of colors, and then condenses and bonds to the substrate to images, and designs. form a chrome-like layer. A protective topcoat is The particular type of dye that is used vaporizes then applied to the surface. The coating is much when heated, bonding to the molecules of the cheaper and more environmentally friendly than plastic substrate and absorbing the color into the chrome plating, although it does not reach quite component down to a depth of 20–30 microns. the same high level of durability and corrosion- As a result, the surface cannot wash or rub off, resistance. Although the plastic component will making a fully decorated product that is highly not have the weight or coldness of real metal, it is durable and scratch resistant. The technique is worth considering for parts that will not be touched also used to create decorative surfaces for a variety by the user’s hands; this might help to carry the of applications, including the lid of Sony’s VAIO illusion off more easily. An application that uses the laptop computers. The computers are decorated process for enhanced illumination is in the cones with a range of different colors and graphics to give for torches. Tom Dixon applied it to a different form them personality and individuality. of illumination in his copper shade made from polycarbonate plastic with a metalized copper Typical application fi nish (above, www.tomdixon.net). Sublimation dye printing is also used in photo- quality printers, where colors are printed as solid Typical application dyes which are heated up and permeate the paper The conical fl ashlight refl ectors at the end of every before returning to solid form. This creates a much torch and car headlight, and automotive trim with higher-quality image than dot-matrix printers such a chrome-like shine, are both products that use as inkjets and laser printers, and the prints are less vacuum metalizing. vulnerable to fading and distortion. Sustainability Sustainability Vacuum metalizing uses aluminum to create The process is effi cient and safe for the environment. a chrome-like effect, which is much more However, a great deal of heat is produced and environmentally friendly than chrome plating. energy usage can therefore be an issue. Further information Further information www.muellercorp.com/chromeplatingplastic.htm www.kolorfusion.com www2.dupont.com

LK016_P0260EDmakingIt2us.indd 262 16/09/2011 15:17 Finishing Techniques: Decorative 263

Flocking Acid Etching

Flocking is a surface that has very strong Also known as chemical milling or wet etching, assocations: fuzzy felt and my mother’s acid etching is great for producing intricate patterns in the 1970s, and the repellent feel of scraping on thin, fl at metal sheets. It involves a resist being fi ngernails over that tight, furry surface. It’s printed onto the surface of the material to be a technique that was traditionally used for treated. The resist consists of a protective layer that decorative purposes, but also has many other is able to withstand the corrosive action of the acid, practical advantages, such as sound and heat which therefore eats away only the exposed metal. insulation, which make it ideal for a wide variety The resist can be applied in the form of a linear of applications. An unusual example is the special pattern, a photographic image, or any combination edition Miele 56 vacuum cleaner (above). of the two. Flocking involves applying precision-cut lengths of fi bers to an adhesive-coated surface, using an Typical application electrostatic charge. This creates a seamless fabric- Acid etching is often used in precision electronic like coating, with up to 150,000 fi bers per square components such as switch contacts, actuators, and inch. The length and type of fi ber used determines microscreens, and can also be used for labels and the type of fi nish produced. signs. Designer Tord Boontje used the process to produce his Wednesday Light (above), a lampshade Typical application that folds out from incredibly detailed sheets of Flocking is widely considered to be simply etched stainless steel. Acid etching is used in decorative, but it has a number of advantages that the military to make a fl exible trigger device make it suitable for a wide variety of purposes. on missiles, which is so sensitive it bends For example, it is commonly found in the interiors according to air pressure the closer the missile of cases for spectacles, jewelry, cosmetics, and so gets to its target. on where protection is required. Flocking can also reduce condensation, so is often used for motor Sustainability homes, boats, and air-conditioning systems. Two of Many metals are recyclable and the use of toxic the most innovative design applications are coating chemicals is minimized in modern forms of ceramic tableware with a fl ock surface and the acid etching, which gives the process a good special-edition vacuum cleaner featured here. environmental rating.

Sustainability Further information Any excess fl ocking that does not attach to the www.precisionmicro.com surface can be collected and reused. Products which have been fl ocked can be recycled, depending on the type of fi ber and base material used.

Further information www.krekelbergfl ockproducts.nl

LK016_P0260EDmakingIt2us.indd 263 16/09/2011 15:17 264 Finishing Techniques: Decorative

Laser Engraving Screen Printing

You probably have some idea of how engraving Screen printing is arguably the most versatile of works, and are familiar with its use for lettering on all printing techniques. It can be used with many objects like trophies and plaques. However, laser different types of material, including textiles, engraving can produce microscopic details that ceramics, glass, plastic, paper, and metal, and can are so accurate and precise that it can be used also be used to print onto objects of any shape, to produce printing plates for banknotes that are thickness, and size—making it ideal for a broad diffi cult to counterfeit. Although there are various range of applications. types of engraving, it is now usually done with The process relies on a woven mesh screen a laser, as this is particularly effective for mass- which is stretched tightly over a frame. The graphic production and intricate detailing. pattern is produced on the screen by masking off The engraving machine uses a laser that acts the negative spaces, either manually or using a like a pencil—the beam is computer-controlled photochemical process. Ink is forced through the to trace patterns on the surface of the material. threads of woven mesh and onto the open areas of Direction, speed, depth, and size can all be fi ne- a stencil using a roller or squeegee. This produces tuned to suit the application. Laser engraving does a sharp-edged shape on the surface. The type of ink not use tool bits or contact the surface in any way, used, diameter of the threads, and thread count of so parts do not need to be regularly replaced as they the mesh all affect the fi nal image. do with hand engraving. Typical application Typical application Screen printing is most commonly associated with Some of the highest quality hand engraving can be clothing, but the technique is used for many other found on jewelry, but jewelers have realized that applications, including clock and watch faces. by using a laser they are able to engrave with even More excitingly, it is now being utilized for more greater precision and at a much greater speed. advanced uses like laying down conductors and Because the laser can cut into both fl at and curved resistors in electrical circuits that are on top of surfaces, the process has become particularly ceramic materials. effective in this area. A rotary screen printer is used to speed up Laser engraving has another, slightly more the process of printing onto T-shirts and other unusual application—in architectural models, garments. The clothing industry accounts for where it can be used to create very fi ne details over half the screen printing done in the US. and patterns. Sustainability Sustainability The screen can be reused once it has been cleaned. Unlike many other surface decoration processes, Screen printing can produce prints at a much laser engraving does not involve consumables or quicker rate than comparable methods, making problems with toxic by-products. However, some it more effi cient in terms of energy consumption. materials do emit hazardous gases when they are laser-cut. Further information www.fi ngerprint-comms.co.uk Further information www.norcorp.com www.csprocessing.co.uk

LK016_P0260EDmakingIt2us.indd 264 16/09/2011 15:17 Finishing Techniques: Decorative 265

Electropolishing Tampo Printing

Tampo printing is a versatile technology that can be used on virtually any material or surface. It is a very effective way of creating high-standard graphics or other decoration on complex parts, as it allows the graphic to be printed onto small, confi ned surfaces and curves. However, only solid colors with no gradients or tints can be produced. The process begins with the graphic being produced on a fi lm, to exact size. It is then chemically etched onto the surface of an anodized plate. The plate is positioned in the tampo printing machine where ink is distributed across the surface. The plate is then scraped clean so that the only Many metals that look and feel smooth to the touch ink is within the etched graphic. A silicone pad are, in fact, the opposite. Examining a surface is lowered onto the metal plate and the ink of the under a microscope can reveal that it is full of tiny graphic is picked up. The silicone pad then moves imperfections, which may affect how well the metal and presses the graphic onto the surface of the item performs in use. This is where electropolishing being printed. comes in. It uses an electrochemical process to remove a thin layer of the metal, to expose Typical application a cleaner, brighter, and smoother surface. Tampo printing is the main method used to print Electropolishing is in effect the opposite logos on general promotional merchandise such of electroplating, where material is added to a as pens and key rings. It is also useful for such surface. The process begins with immersing the products as calculators, radios, clocks, and torches. work piece in an electrolyte bath through which an is passed. This starts an Sustainability oxidation process, that causes the surface of the The tampo printing machine is CNC-controlled, metal to dissolve. Increasing the processing time using lasers to set up parts accurately and quickly, removes more metal. The image above shows the which makes the process energy effi cient. process applied to the Berta Vilagrassa bench by KX Designers. Further information http://www.aki.co.uk/page/tampo_pad_printing Typical application Electropolishing removes all traces of hydrogen from the surface, which greatly restricts the growth of bacteria. For this reason, it is commonly used in the food industry for food-processing and food- handling equipment. The process is ideal for small and complex products made from alloys such as copper; almost any other fi nishing method will damage such soft metals.

Sustainability Although electropolishing involves the use of potentially harmful chemicals, the electrolyte bath can be used over and over again for a number of components, with a minimal amount of waste.

Further information www.willowchem.co.uk

LK016_P0265EDmakingIt2us.indd 265 09/11/2011 13:35 266 Finishing Techniques: Decorative

Suede Coating Hot Foil Blocking

Think of a peach skin or a fi ne fl ocked surface, then Hot foil blocking is a “dry” process, which means add a subtle rubbery feel and you have what was no inks or solvents are involved and the work can the material of the moment in the 1990s. Nextel®, be handled straight after it has been blocked. It a surface coating with the velvety feel of the skin is versatile and can be used on a whole range of of a peach, was developed at the request of NASA, materials. The result is a decorative effect that has who needed a coating with some specifi c and a brilliance that cannot be produced using inks. demanding properties. The initial use for Nextel® was interior surfaces on space shuttles, which need To begin the process, a metal blocking die or plate to be antistatic, chemically inert, and nonrefl ective, is produced by etching the graphic into the metal as well as scratch resistant. However, the coating so that it is raised. The die is placed in the blocking is now used in all kinds of industries for both machine, which consists of a roll of foil and a shelf decoration and function. beneath the foil where the material to be printed Nextel® is very easy to apply and consists of is placed. When the die is pressed down onto neoprene granules in a special carrier medium. the foil, the heat and pressure from the die cause The coating consists of three layers. The fi rst is the the pigment in the foil to be released and this is substrate, which is coated with the second layer—a transferred onto the material in the shape of the suitable primer. Once this has dried, color is applied raised image on the die. Hot foil blocking is often and tiny neoprene granules, which make up the combined with embossing to make graphics stand third layer of the coating, are then added. Standard out even more. industrial spraying equipment is used and the coating is either air-dried, or alternatively, dried in a Typical application low-temperature oven. Typical applications for hot foil blocking include book covers, business cards, toys, and premium Typical application packaging. The process can also be used for some Applications for Nextel® are almost unlimited, but more unusual applications, such as labeling shoes the range of materials that can be coated makes and the holographic detail on credit cards. it particularly suitable for interior design. Its toughness and aesthetic properties mean it is ideal Sustainability for furniture for both offi ce and domestic furniture. Hot foil blocking does not use a lot of energy, The coating has also been widely used in although there is inevitably some waste material. the fi eld of transportation. Car dashboards, and seating for trains and airplanes, are just a few of the Further information applications that make use of this hard-wearing and www.glossbrook.com soft-surface fi nish.

Sustainability Nextel® conceals imperfections such as dimples on the surface of the substrate. This reduces the number of processes that are required and therefore the amount of energy used. Little or no waste is produced during the application of the coating.

Further information www.nextel-coating.com

LK016_P0260EDmakingIt2us.indd 266 16/09/2011 15:17 Finishing Techniques: Decorative 267

Over-Molding Sandblasting

Over-mold decoration is often seen as an extension of injection molding, rather than a manufacturing process in its own right. It is, however, an incredibly useful tool that enables designers to add almost craftlike qualities to products because of the way it allows for different materials to be combined. Although it is capable of producing very complex products, the process is in itself fairly straightforward. The main part is molded before being transferred to the next mold, where a second material is molded around, over, under, or through the base molding.

Typical application This process is versatile, as it can be used to smooth Over-molding is often used for products that fall and shape objects, also for producing decoration into the category of personal mobile technology, similar to etching or carving. including cell phones, PDAs, and laptops. Sandblasting does exactly what it says: abrasive A number of cell-phone cases have a small particles are fed through a gun at very high speed, patch of fabric on their surface. You would imagine and effectively blast the work piece. For obvious that adding the fabric would require a whole new reasons, the safest way to use the process is process, but over-molding allows for plastics to be inside a sealed chamber. In terms of decoration, combined with other materials during the actual sandblasting glass can be very effective and is molding process, which eliminates the need for any considered to be something of an art form. It is secondary fi nishing. possible to create all kinds of decorative patterns by using stencils, and simply adjusting the speed Sustainability and angle of the propelled particles creates different It can be diffi cult to recycle over-molded products, shades, depths, and effects. as they consist of a combination of materials which, in many cases, aren’t easily separated. This is Typical application largely a problem for designers, who need to bear In addition to decoration, sandblasting is used to this in mind and make sure the product can be restore automotive parts, architectural structures, dismantled effectively. and mechanical components, as it removes rust and corrosion. It has also been used to prime objects Further information before painting. The small abrasive particles ensure www.ecelectronics.co.uk that all imperfections are smoothed out and that dirt and dust are removed, which makes the paint stick better. One of the biggest uses has been for making denim jeans look distressed. However, inhaling the dust particles emitted during sandblasting can be hazardous. Legislation has been introduced to ensure factories operate with the appropriate setup. In some cases the process has been banned.

Sustainability The main alternatives to cleaning or altering the surface of a material are chemical based. Therefore, in comparison, sandblasting, which uses air (relatively low energy) and grit is more environmentally friendly.

Further information www.lmblasting.com

LK016_P0260EDmakingIt2us.indd 267 16/09/2011 15:17 268 Finishing Techniques: Functional Functional i-SD System In-Mold Decoration (Film Insert Molding) i-SD is a new surface coating that provides an In-mold decoration was developed as an alternative to traditional hydrographics. It allows for economical way of adding decorative surfaces highly accurate graphics to be draped over complex, to injection-molded plastic parts. It eliminates 3-D surfaces without distorting the image. The ink the need for a separate printing process and covers the entire shape, including cavities, recesses, is becoming more and more signifi cant with and detailed surface textures, from an original, the increased use of graphics and branding to high-resolution image. The process is compatible personalize consumer products such as cell phones with many base materials, including plastics, wood, and other electronics. metal, glass, and ceramic. With PBT plastic the The process begins with printing the graphic image is actually embedded in the plastic so that it onto a polycarbonate or polyester fi lm, known as a won’t wear off. “foil,” which is then cut to shape. Depending on the shape of the component to be molded, the foil is fed Typical application into the mold as a ribbon, or cut into individually The i-SD process is currently being used in inserted pieces if the part is curved. automotive applications where high wear- resistance is needed, but there is also a huge area Typical application of opportunity in cell-phone covers and decorative In-mold decoration is not limited to text-based surfaces for other consumer electronics. graphics, but can also be used to produce color and surface patterns on moldings. One of the Sustainability most interesting, albeit invisible, foils that can Through the combination with injection molding be applied is a form of “self-healing” skin which the process results in faster production cycle helps products stay shiny and free from scratches. times, resulting in less energy consumption than Other applications include decorative cell- comparable decoration processes phone covers, digital watches, keypads, and automotive trims. Further information www.idt-systems.com Sustainability In-mold decoration is more environmentally friendly than painting or spraying, which emit volatile organic compounds (VOCs).

Further information www.macdermidautotype.com

LK016_P0260EDmakingIt2us.indd 268 16/09/2011 15:17 Finishing Techniques: Functional 269

Self-Healing Liquid-Repellent Coating Coatings

This clear polyurethane coating has the ability to Traditionally, liquid-repellent coatings rely on heal itself, repairing small scratches and blemishes treating textiles and other materials with an on a product’s surface, when exposed to heat. At impermeable coating, which generally completely high temperatures, the network of molecules in alters the look and feel of the original material. this plastic coating becomes elastic and it fl exes, P2i, on the other hand, produce a nanoscopic enabling it to smooth out scratches, similar to the liquid-repellent coating based on plasma-enhanced way in which candle wax reacts when it is heated. vapor deposition technology. This uses a special The coating provides outstanding durability and pulsed plasma, operating in a vacuum chamber resistance and could make the problem of scratches at room temperature, to polymerize a liquid- a thing of the past. repellent monomer and attach it to the surface of A good example of its use is for a car body. the object being protected. The process forms a When the car is exposed to sunlight on a hot day nanometer-thin, durable protective coating over small scratches on its sheet metal simply fl ow back every exposed surface of the object, making it together, improving smoothness and gloss. completely liquid repellent, while leaving its other properties unchanged. The process works with a Typical application wide range of materials; even complex 3-D objects The coating has been tested for car-body sheet incorporating several different materials can be metal, but its possibilities are vast—perhaps even treated successfully with the P2i process. encompassing self-healing building surfaces? Typical application Sustainability The technology can be used to provide protection This self-healing coating is environmentally friendly from liquids for a wide range of products, including as it uses only a small amount of solvents. electronics under P2i’s Aridion™ brand and footwear under its ion-mask™ brand. Entire products, Further information including seams and joints, can be coated in one go. www.research.bayer.com/en Laboratory equipment and medical products are also important areas for the technology—for example, when applied to pipettes it ensures that all their liquid content is released for accurate test results.

Sustainability The process requires only tiny quantities of protective monomer and waste is minimal, making it highly effi cient compared to traditional methods such as dip application and spraying.

Further information www.p2i.com

LK016_P0260EDmakingIt2us.indd 269 16/09/2011 15:17 270 Finishing Techniques: Functional

Ceramic Coating Powder Coating

Keronite® is a brand name for an extremely hard, Powder coating is a completely dry process; the wear-resistant ceramic coating that can be used with coating is made from a combination of fi nely ground light metals and alloys, and has transformed surface resin, pigment particles, and other raw materials, engineering. It provides a more environmentally which are applied to the surface of an object. friendly, cost-effective, and precise alternative to hard Tougher than conventional paint, it can be applied chroming and plasma spraying. much more thickly without running or sagging. The The application process starts with immersing process offers a choice of using a thermoplastic or the object in an electrolyte solution with an electric thermoset polymer base material; the thermoplastic current passing through it. This creates a plasma fi lm will remelt upon heating, whereas the thermoset discharge, which forms a thin primer layer in a process polymer will not change state once set. called “plasma electrolytic oxidation” (PEO). Next is Powder coating is most commonly applied by the functional hard layer, in which hard crystallites spraying, using an electrostatic charge to make are packed into a crystal matrix that covers the entire the coating stick to the substrate. The object is part. Although the process is similar to anodizing, it fi rst electrically grounded, then sprayed with a produces much thicker and harder layers while using gun where the powder is passed by an electrode to less environmentally harmful alkali electrolytes. charge the particles, causing an attraction to the grounded object. This electrostatic charge ensures Typical application an even layer of powder. After application, the object Keronite® has a unique combination of properties is placed in an oven where the powder particles melt that makes it ideal for a wide variety of products. and fuse to form a continuous surface. It has been approved for use on satellite hardware in the aerospace industry; the European Space Agency Typical application conducted a thermal shock test where Keronite® The toughness and robustness of powder coating was immersed alternately in boiling water and make it ideal for demanding applications such as liquid nitrogen to mimic conditions in space. bicycle frames and automobile components, where Benefi ts have been most recognized in the fi eld scratching and weather conditions cause problems. of architecture. A light coating of Keronite® makes Because of the need to ground the substrate, aluminum more robust and suitable for structural powder coating was initially compatible only with components. The image above shows a RockShox, electrically conductive materials, such as metals. 2011 Revelation World Cup adjustable bike fork. However, there are various ways to get around this problem and it is now possible to coat other Sustainability materials, including glass and MDF. The electrolytes used in this process do not contain environmentally damaging components and can Sustainability be disposed of without treatment. Keronite® is The process does not emit any volatile organic 100 percent recyclable. compounds (VOC) into the air. Additionally, unused or over-sprayed powder can be recovered and reused. Further information www.powdertech.co.uk Further information www.keronite.com www.dt-powdercoating.co.uk

LK016_P0260EDmakingIt2us.indd 270 16/09/2011 15:17 Finishing Techniques: Functional 271

Phosphate Thermal Spray Coatings

First developed at the turn of the twentieth century, This process is an extremely effective way phosphate coatings are still in common use today of increasing a component’s lifespan and as a way of enhancing the properties of iron and performance. Although there are four types of steel parts. The coating acts a bit like a primer or thermal spraying, the fundamentals are very base coat for metals, as it gives a great surface similar: a powder or wire is fed through a spray for painting while protecting against corrosion pistol, where it is heated until it is molten or soft and wear. and it is then sprayed onto the substrate. Thermal As with many other fi nishes, the process spraying can provide thick coatings over large areas begins with cleaning the component to be coated. where the density of the coating depends on the Depending on its shape and size, the part is then material used. placed on a rack, or in a basket or barrel, and The different forms of the process are: fl ame, immersed in a solution, where a thin compound of arc, plasma, and high-velocity oxy fuel spraying, phosphate crystals forms over its entire surface. each of which uses various materials suited Three types of phosphate are used. Zinc to a variety of applications. For resistance to phosphate provides an excellent base for paints atmospheric corrosion, thermal sprays are an and has good anticorrosive properties, whereas excellent alternative to platings and paints, and iron phosphate creates a good surface for bonding have the added benefi t that they are much less to other materials. Manganese phosphate is harmful to the environment. particularly effective at absorbing oil and also provides excellent resistance to wear. Typical application Thermal spraying has been remarkably successful Typical application in very demanding situations, such as electrical Phosphate coatings are used to prolong the life and insulation for surgical scissors and improving the minimize the maintenance of mechanical parts in a performance of bicycle brakes. wide variety of applications, including automotive, Due to its high cost, it is mainly used in aerospace, and other heavy industries. They have the aerospace, automotive, and biomedical also been shown to improve the biocompatibility of industries, and for printing, electronics, and orthopaedic and dental implants, reducing the risk food-processing equipment. of rejection by the body. Sustainability Sustainability No volatile organic compounds (VOCs) are used, The phosphate-coating process involves the use of making thermal spraying an environmentally harmful chemicals. However, the coatings provide friendly process. excellent wear-resistance and corrosion protection, which prolongs the lifespan of product parts. Further information www.twi.co.uk Further information www.csprocessing.co.uk

LK016_P0260EDmakingIt2us.indd 271 16/09/2011 15:17 272 Finishing Techniques: Functional

Case Hardening High-Temperature Coatings

Case hardening is a simple method used to harden Diamonex is a thin but extremely hard-wearing mild steel. Heavy steels have a high carbon content coating with a diamond-like fi nish. It is normally and can be hardened by heating, whereas the possible to apply it at temperatures lower than carbon content in mild steel is too low for this. 300°F, meaning Diamonex can be used with a wide Instead, carbon is forced into the skin of the metal range of materials, including plastics. In addition to to produce a mild steel with an extremely hard outer its good wear- and abrasion-resistance, the coating surface, or casing, and a fl exible and fairly soft core. is chemically inert and very hard with low friction. The process begins with heating the steel until it is red-hot. A part can be partially heated if only Typical application a smaller section needs to be hardened. The steel This incredibly versatile coating is used in is then plunged into a carbon solution before being everything from jet engines to supermarket heated again and fi nally placed in cold clean water checkout scanners—basically any application to cool. This process can be repeated to increase the that requires super-tough wear-resistance and low depth and strength of the hardened surface. friction. Diamonex is also suitable for many medical applications, including implants and surgical Typical application instruments. There are many applications for this process as it is suitable for all kinds of components that have to Sustainability withstand high pressure and impact. Essentially, Diamonex is an effi cient coating process that case hardening takes a material that is easy to doesn’t leave much waste. However, it is worth shape—mild steel—and makes it very hard-wearing bearing in mind that coated products are diffi cult to and durable. Treated parts cannot be cut with a saw recycle and reprocess. and will not shatter easily. Further information Sustainability www.diamonex.com Case hardening is not particularly effi cient and it can be diffi cult to recover wasted material.

Further information www.ttigroup.org.uk

LK016_P0260EDmakingIt2us.indd 272 16/09/2011 15:17 Finishing Techniques: Functional 273

Thick-Film Protective Metalizing Coatings

Thick-fi lm metalizing makes it possible to “print” The surface of glass is considered to be completely a layer of metal onto plastics and ceramics. It can, smooth, but on a microscopic level it is quite rough in other words, be used to print fully functional with tiny peaks and craters that cause dirt to stick conductive circuits directly onto the substrate, to the surface. Diamon-Fusion® is a glass coating without the need for separate circuit boards. that improves the propoerties of glass while also The coating can be applied by screen printing, protecting it. The coating fuses with glass to form a spraying, and roller coating, and by using a laser water-repellent barrier that also enhances visibility where the metalized pattern is “printed” directly and strengthens the maximum weightload of onto the product. the material by up to ten times that of untreated glass. Diamon-Fusion® is also suitable for ceramics Typical application and most other silica-based materials, including One of the most common uses for thick-fi lm and granite. metalizing is in so-called RFID (radio frequency Diamon-Fusion® is applied using a process identifi cation) tags. These are often used in the called “chemical vapor deposition.” The surface to shipping industry to track parcels and other goods, be treated is fi rst cleaned and coated with a liquid and also in wireless ticketing systems, such as catalyst. A special machine then emits a vapor London’s public transportation Oyster card. But containg the special chemicals needed to make the it could be used for so much more. Already, next molecules change. The process happens inside a generation rapid prototyping machinery has chamber that can be big enough to fi t very large incorporated thick-fi lm metalizing technology, products. It takes only a short while and the glass allowing designers to integrate working circuitry in can be used straight away. their prototypes. Typical application Sustainability This versatile coating is used in glass and ceramic Because the metal is deposited directly onto the coating from bathroom fi ttings to car windscreens, part, thick-fi lm metalizing wastes only a minimal where it can make a big difference in improving amount of materials. However, the metal must visibility and keeping the window clear during bad be removed to allow for of weather. Diamon-Fusion® also provides protection the product. against damage from road debris, ice, and snow, as well as acid rain and UV radiation. The coating is Further information suitable for applications in marine environments. www.americanberyllia.com www.cybershieldinc.com Sustainability Once the coating is applied to the glass it is chemically inert and completely nontoxic. The vapor deposition process used to create Diamon-Fusion® is also environmentally friendly. Additionally the use of the coating can lead to reduced cleaning cycles, which is good for the environment and uses less energy.

Further information www.diamonfusion.com

LK016_P0260EDmakingIt2us.indd 273 16/09/2011 15:17 274 Finishing Techniques: Functional

Shot Peening Plasma-Arc Spraying

Plasma is often referred to as the fourth state of matter. In the same way that suffi cient cooling causes most materials to freeze, most solid materials turn into a plasma state when they are heated up enough. Plasma is very similar to a gas, but it has a unique property: it conducts electricity. Plasma arc spraying provides protection against high temperatures, corrosion, erosion, and wear. It can also be used to replace worn material or to enhance the electrical properties of a material. The coating is compatible with a variety of base materials and can be produced in different thicknesses. Shot peening is a process for cold-working metal The spray material is usually a powder that is surfaces to improve their strength and overall heated up and melted inside a spray gun. Once physical properties. To understand the process, the material is molten, a gas that fl ows between think of a shotgun—shot peening basically involves an electrode and the nozzle is used to propel it to pummeling a metal surface with lots of small round the work surface. Finally, as the material hits the particles. The particles cause small dimples as surface it solidifi es rapidly to form a solid coating. they hit the surface, which creates a layer of highly stressed compression as the material beneath the Typical application surface tries to restore itself. The resistance to high temperatures offered On a superfi cial level, shot peening is similar by plasma arc spraying is ideal for demanding to sandblasting, but without being abrasive; this applications in the aerospace industry, where means that less material is removed during the a number of parts within turbine engines are process and that in some cases shot peening is sprayed so that they are able to perform in even suitable for forming. extreme conditions. The process can in some cases increase fatigue Medicine is another fi eld where plasma-arc life by up to ten times. As well as increasing spraying is hugely effective. The coatings are strength, shot peening resists some forms of biocompatible, which allows a bond to be created corrosion as it is diffi cult for cracks to form on between an implant and tissue. the treated surface. Sustainability Typical application Waste spray can be collected and reprocessed, Shot peening can be used for all kinds of making plasma-arc spraying an effi cient process. applications—from architectural cladding to strengthening aircraft wings—where increased Further information strength in metallic sheet materials is desirable. It www.plasmathermalcoatings.com is also sometimes used for forming, as opposed to just fi nishing, in aerospace industries. Additionally, the process can be used to strengthen materials after repairs.

Sustainability Because shot peening is a cold-working process, it uses less energy than fi nishing processes that require heating. Unlike with sandblasting, little dust is created.

Further information www.wheelabratorgroup.com

LK016_P0260EDmakingIt2us.indd 274 16/09/2011 15:17 Finishing Techniques: Functional 275

Galvanizing Deburring

All machining processes—from shearing to drilling—inevitably cause untidy, rough, and sharp edges on metals. These are called “burrs” in the industry and deburring is the technique used to remove them. There are a number of ways to remove the burrs, depending on the type of metal used and the shape of the product. The most common is to use a tumbler: the part is placed inside the drum along with small chips of various materials. It is then tumbled around inside the machine until all sharp edges have been ground down. The process also cleans, softens corners, and sometimes even One of the unique advantages of galvanizing is its improves the strength of the part. structure. The reaction between metals that the process causes, causes the coating actually to merge Typical application with the base metal to create outstanding toughness Deburring is a critical step in the manufacture and enhance the longevity of metal parts. of parts for the aerospace industry. For example, A lot of preparation is involved in the process, the parts for a turbine engine will be subjected to as the part that will be coated must be completely extremely high pressures and temperatures during and utterly clean if the reaction is to happen. So the use, which means all the edges must be completely part is fi rst cleaned with a degreasing solution, then smooth with a generous radius. The process is washed with water and placed in an acidic bath to simple enough to be used for post-cleaning any remove rust and scale. Once it is entirely clean, it metal parts. is dipped into molten zinc, which causes the zinc and the base metal to form a tough and inseparable Sustainability protective layer all over the surface. The initial rate Automated deburring machines use a great deal of reaction is very rapid and most of the thickness is of energy. formed at this time. The part is typically immersed in the molten zinc for about 4–5 minutes, but it can Further information be for longer for larger products. www.midlanddeburrandfi nish.co.uk

Typical application The galvanizing of steel parts is widely used within the construction industry. Steel bars, bolts, anchors, rods used in reinforced concrete, and highway crash barriers are common applications that benefi t from the increased durability and toughness the process offers.

Sustainability Galvanizing involves the use of some fairly nasty chemicals and acids, but the process is not a major environmental concern if it is managed properly.

Further information www.wedge-galv.co.uk

LK016_P0260EDmakingIt2us.indd 275 16/09/2011 15:17 276 Finishing Techniques: Functional

Chemical Polishing Vapor aka ElectroPolishing Metalizing

Many components for electronic devices need to Vapor metalizing may not be the best known be extremely accurate geometrically and must fi nishing process, but it has quickly become one have an equally high degree of surface fi nish. of the most common ways to produce mirrors. It Chemical polishing achieves what can be very allows bright and refl ective metal coatings to be high tolerances in manufacturing, allowing for applied, very cost-effectively, to a variety of base “microscopically featureless” surface smoothness materials, including plastics. Vapor metalizing can with minimal surface and structure damage. also be used as an alternative to electroplating in The process works by exposing the component some applications to coat some parts of a surface to controlled chemical dissolution in an acid bath. and leave others uncoated. The acid attacks ridges and rough surfaces, causing The object to be coated is placed inside a jig them to dissolve faster than fl at parts and leaving and an adhesive base coat is applied in order a perfectly smooth surface. If you are familiar with to enhance the metalizing process and ensure electroplating, think of electropolishing as the a durable coating. The base coat is cured in an reverse, where metal ions are removed from oven, and the object is then placed in a vacuum a surface instead of being added to it. chamber and evaporating aluminum (less common alternatives include nickel and chromium) forms Typical application an even coat all over the object. A protective Chemical polishing is used for high-precision topcoat is often applied as well. products such as electronics, jewelry, medical devices, razor blades, and fountain pens. Typical application Because vapor-metalized parts are resistant Sustainability to water corrosion, the process can be used for The chemicals used in the process are aggressive a number of car parts including side mirrors, but manageable, and excess material can door handles, and window trims. Kitchenware be recycled. and bathroom fi ttings are common applications, as are metallic helium-fi lled party balloons. Further information Vapor metalizing can also be used to give plastic www.logitech.com materials a conductive metal coating. Packaging www.electropolish.com is another important area—just look at a packet of www.delstar.com potato chips to see an example of metallic coating of plastic fi lm.

Sustainability Vapor metalizing is more environmentally friendly than comparable processes such as electroplating, because it is cleaner and doesn’t use toxic chemicals.

Further information www.apmetalising.co.uk

LK016_P0260EDmakingIt2us.indd 276 16/09/2011 15:17 Finishing Techniques: Functional 277

Decalization Pickling

Decalization is used to apply photographic images, And no, this is not pickling as in preserving or any other graphics, to a wide range of substrates. food. In this context, pickling is a method of It works by coating a base material with a layer cleaning various metallic surfaces. All kinds of of polyurethane, which is then printed, using manufacturing processes from cutting to welding screen or offset printing, at temperatures of up to can tarnish metals by leaving residue caused by 390°F. The heat causes the ink and polyurethane oxidation, which discolors the surface. Before to fuse, resulting in a very durable and scratch- any additional layers, such as paints and coatings, resistant surface. can be applied to the metal the residue must Decalization’s toughness, coupled with its be removed. This is where pickling comes into ability to coat a wide range of materials, including the picture. plastics, metal, glass, and MDF, makes the process The metal part is submerged in a bath of extremely versatile, and suitable for everything cleaning chemicals and heated up. It can take just from architectural exteriors and interiors, a few minutes, or up to several hours, before the transportation, and outdoor advertising to metal can be removed and washed. Large items can all kinds of consumer products. be sprayed with the chemicals, or a brush can be used to coat just specifi c areas. Typical application By improving corrosion-resistance, pickling Decalization is perfect for demanding architectural signifi cantly increases the life cycle of a product applications, such as bathrooms and kitchens—and and improves its performance in use. It uses a even exteriors as it is UV-, abrasive-, and graffi ti- variety of cleaning chemicals which are generally resistant. It is also suitable for high-maintenance determined by the type of metal being processed. areas such as public transportation, stations, and These include acids which remove a very tiny layer sports arenas. of the surface and therefore any scale.

Sustainability Typical application Surfaces coated with this process cannot be Pickling is often used in jewelry. Because the recycled, but in many applications the toughness condition of the metal—which often involves and durability it produces may lead to reductions in copper, silver, or gold—is important, any scale left materials, maintenance, and replacements. after it has been soldered or fl uxed needs to be removed from the surface. It is possible to purchase Further information a pickle pot and process small items at home. www.decall.nl Sustainability The waste products produced by pickling can be hazardous. However, the waste liquor can be reprocessed for the fertilizer industry. Alternatively, it can be recycled and used in the manufacture of steel.

Further information www.anapol.co.uk

LK016_P0260EDmakingIt2us.indd 277 16/09/2011 15:17 278 Finishing Techniques: Functional

Nonstick Coating Nonstick Coating (organic) (inorganic)

Based on plant cells, Xylan® is an organic range T e fl o n ® is a brand that has captured the public of fl uoropolymer coatings that can improve imagination, to a degree that it is widely used, the properties and usability of a wide range of in all kinds of contexts, to describe a thing’s, or materials. Like PTFE (more commonly known as even a person’s, nonstick qualities. The scientifi c T e fl o n ®) Xylan is used for nonstick surfaces; the name for this plastic material is a mouthful— main difference is that it adheres very effectively to polytetrafl uoroethylene, PTFE for short—so we surfaces that would not usually accept PTFE. should be thankful to the engineers at DuPont™ The product to be coated is fi rst degreased and for coming up with its catchy brand name. cleaned so that the coating will stick properly. The It is is extremely diffi cult to process this material coating is then applied in the form of a wet spray, using conventional methods for forming plastics, which contains the fl uoropolymer resin. The product which is why PTFE is almost always used to coat is placed in an oven where the Xylan® cures and other materials. The process works by spraying the forms a thin fi lm. The thickness of the coating substrate, then curing the coating in an oven where depends upon the number of coats that are applied. the PTFE forms a tough and uniform fi nish with remarkable properties: excellent self-lubrication Typical application and nonstick properties, and chemical- and heat- Xylan®’s ability to increase the lifespan and resistance. Other non-Tefl on®, nonstick coatings performance of various components makes it include Xylan® (see right). particularly effective in the automotive industry. Here, aluminum is often used because of its low Typical application weight, but at the cost of the material’s relatively T e fl o n ® and PTFE are probably best known in scant durability. The use of Xylan® in this connection with cookware, but the coating is also area helps aluminum to resist wear even in extensively used in textiles, such as GoreTex®, an environment of heat, oil, and friction. for improved weatherproofi ng. It is also used for medical equipment, where its heat- and chemical- Sustainability resistance help to maintain exacting standards of The lifespan and performance of a component cleanliness and sterility. is signifi cantly increased, reducing the use of raw materials. Sustainability PTFE and in particular one of its ingredients— Further information PFOA—is often said to be a potential threat to the www.ashton-moore.co.uk environment. It is worth noting that DuPont has recently removed PFOA from the Tefl on® production process and that the US Environmental Protection Agency does not advise against normal use of nonstick cookware and PTFE-coated all-weather clothing.

Further information www.dupont.com

LK016_P0260EDmakingIt2us.indd 278 16/09/2011 15:17 Finishing Techniques: Decorative & Functional 279 Decorative & Functional Chrome Plating Anodizing

Chrome plating is a technique commonly used for One of the most interesting facts about this coating objects that require particular resistance to fi nish is that it is a protective skin that is grown corrosion and wear. There are typically two types from aluminum, toughening and thickening the of chrome coating, the most common of which is natural oxide that is contained in the metal. The the thin, decorative, bright chrome that can be components to be anodized are thoroughly cleaned used on a wide range of products, followed by before being immersed in a sulfur solution. A hard chromium plating, which is much thicker and current is passed through the aluminum component is often used on industrial equipment to reduce and converts the aluminum surface to form the friction and wear. aluminum oxide layer. The thickness and hardness The component must be thoroughly cleaned and of the coating are determined by the strength of buffed in order to create a smooth, even surface. the electrical current, the temperature of the sulfur It is then electrically charged and immersed in solution, and the length of time the component is the chromium solution which is also charged. The immersed in the solution. There are various forms charges cause an attraction between the surface of of anodizing chosen according to whether the main the component and the solution which produces an requirement is production or decoration. Although even layer over the entire surface of the object. aluminum is the main metal used for anodizing, titanium and magnesium can also be anodized; Typical application just think of the metals as “the three -ums.” Chrome plating fi rst became mainstream within the automotive industry for detailing such as bumpers, Typical application handles, and mirrors, as chrome has excellent Apple’s Mini and Shuffl e iPods used anodizing resistance to corrosion. to create a tough and protective coating for Bathroom fi xtures are another important area the aluminum casing, while offering a variety where chrome plating is applied, it is suitable of seductive colors. Another design icon is the in other applications where moist and humid Maglite® torch (p.18), which uses anodizing to conditions are common. It is also used in purely communicate an industrial aesthetic. The low decorative applications such as the Pizza Kobra weight of aluminum and the durability and light by Ron Arad. corrosion-resistance of anodizing is a perfect combination for this type of application. Sustainability Chrome is diffi cult to recycle as some compounds Sustainability are toxic and can have a damaging effect on the More environmentally friendly than many of the environment. Although the production of chromium other metal fi nishing processes, anodizing releases can release harmful emissions, the process has fewer toxins in comparison. An anodized fi nish improved environmentally since 1970. is nontoxic and the chemical baths used in the process are often reclaimed, recycled, and reused. Further information www.advancedplating.com Further information www.anodizing.org

LK016_P0279EDmakingIt2us.indd 279 09/11/2011 13:35 280 Finishing Techniques: Decorative & Functional Decorative & Functional Shrink-Wrap Dip Coating Sleeve

Shrink-wrap sleeves are used as a protective layer The process of dip coating is similar to dip molding, on a vast range of products and are encountered on but there is one major difference between them: a daily basis. The sleeve is made of a thin plastic with dip molding a plastic object is produced and fi lm that shrinks tightly and encapsulates a product the mold is removed, whereas with dip coating when heated. The shrinking occurs because the fi lm a permanent plastic layer is created over an is manufactured so that the molecules are arranged object made of another material, usually metal. in a random order. Heating the fi lm causes the Dip coating provides a very stable and protective molecules to set and so reduces the size of the fi lm. coating that is often decorative, and also ergonomic Shrink-wrap sleeves are available in a variety of in improving grip on products such as handles. thicknesses, clarities, strengths, and shrink ratios. Sleeves can be made to shrink in one direction The process begins with heating the object to be (monodirectional) or both directions (bidirectional). coated, then placing it in a container and blowing plastic powder over it from all directions to create The fi lm can be printed, which offers excellent an even layer. The heat from the object causes the possibilities for branding and other graphics. It is plastic powder to melt and stick to the surface. often easier to print graphics onto a shrink-wrap The coated object is then returned to the oven sleeve rather than the primary packaging. and reheated until the plastic layer is completely smooth, when the object can be taken out and left Typical application to dry. Shrink-wrap sleeves are commonly used to overwrap many types of packaging, including Typical application drinks cans and bottles, CDs and DVDs, cartons, Dip coating is ideal for grips on hand tools such as books, and even whole pallet loads. They can also and clippers, as the plastic coating provides a be used as a primary covering for foods like cheese softer and more comfortable grip than the substrate. and meats. Other applications include outdoor furniture, automotive clips, and fi tness equipment. Sustainability Shrink-wrap sleeves can be recycled together with Sustainability other plastics. Dip coating can be energy effi cient in longer production runs, when a large number of products Further information can be coated at the same time. www.sealitinc.com Further information www.omnikote.co.uk

LK016_P0260EDmakingIt2us.indd 280 16/09/2011 15:17 Finishing Techniques: Decorative & Functional 281

Ceramic Glazing Vitreous Enameling

Because ceramic materials are porous, most Enameling has been used for thousands of years products made from them would be unable to hold for its decorative and protective properties. It is liquids without a layer of glazing. The glaze gives essentially a sophisticated process that uses heat ceramics a glasslike surface that is impermeable to fuse a thin layer of glass powder onto a metal and protects any surface decoration underneath. surface. Various colors can be produced using To apply the glazing a dry powder is dusted different types of mineral. over the ceramic object using an airbrush, or the The metallic surface of the object to be object can be dipped into the powder. The object enameled is fi rst engraved with the desired is then fi red in a kiln, which causes the powder to pattern or shape. Powdered glass is then carefully soften and fl ow over the ceramic surface. A reaction poured into the grooves of the engraved shape between the ceramic and the powder causes a and the object is fi red in a kiln. The heat melts the strong bond between the two. It is worth noting, powdered glass and the resulting liquid spreads though, that the part of the product that will be evenly within the shape. When the object cools in contact with the kiln must be left unglazed, down the enamel hardens to form a hard, smooth, otherwise it will stick to the kiln—if you have ever glass surface. wondered why the base of a tea cup has a different texture to the rest of it, this is why. Typical application Enamel is resistant to heat and wear, and is therefore Typical application often used in everyday products such as kitchen Ceramic glazes have been used for thousands cooktops, saucepans, and washing-machine drums. of years for all kinds of ceramic products. They Because the coating is completely fi reproof and continue to be used today for cookware, plant the colors remain vibrant for hundreds of years, pots, storage containers, and thousands of vitreous enameling is useful for signs and other other applications. graphics—for example, the famous station signs and maps for the London Underground in the UK. Sustainability Glazing signifi cantly increases the lifespan Sustainability of ceramic products by producing a strong, Enameled products are extremely durable, and the durable, and water-resistant coating. The main brilliance of the original colors is still visible after environmental issue is the amount of heat required hundreds of years. The main issue is the amount of to fi re them. heat required to fi re them in the kiln.

Further information Further information http://glasstechnologys.com/ www.kingfi sherenamelling.com

LK016_P0260EDmakingIt2us.indd 281 16/09/2011 15:17 282 Glossary Glossary

annealing The process of reducing the stresses in a draft angle See draw. material by the application of heat in a controlled manner. draw This is the taper that you will need to consider It involves glass or metal being heated and/or cooled slowly when designing parts using many molding processes. It is in a lehr (an oven or kiln), thus bringing about a relaxing of generally a slight angle that allows parts to be easily ejected the internal stresses in the material. from a mold. axisymmetric A three-dimensional form that is symmetric engineering polymers Plastic materials with around a single axis; a typical example might be a cone. performance characteristics, for example: nylon, acetyls, bar A term used in industry to describe pressure in a vessel. and thermoplastic elastomers (TPEs). Compare commodity 1 bar is equal to 14.504 pounds per square inch (psi), 0.98692 polymers. atmospheric pressure or 100,000 pascals (Pa). fabrication A metalworking term used to describe the billet In engineering terms a billet is a solid lump of steel construction of components by assembling and fixing from which are made rods, bars, and sections. together various parts, rather than the manufacture by, for example, molding or casting in a single operation. biscuit/bisque Refers to a ceramic that has been fired but not glazed. The firing takes place at around 1830°F. fettling A final cleaning-up of a ceramic piece before it is A ceramic piece that is biscuit-fired is porous. fired. burring A rough, often sharp, edge left on a piece of metal flange A lipped detail or rim that is usually straight and after it has been cut, cast, or drilled. Although only a minor located on the edge of a metal part. Its function is to add by-product of various forms of production, it is sufficiently stiffness and to facilitate joining to another part. noticeable that companies have been set up expressly to deal flash In production, the flash (or flashing) is the excess with deburring in its many forms. metal left on a part after a forming operation. It is unwanted CAD Computer-Aided Design. and generally needs to be removed. chip-forming cutting Methods of making components gate This is a term that is mentioned quite often in that create chips of material as a result of the cutting connection with plastic molding. It refers to the orifice process. A typical example would be milling. See also non- through which the hot, molten plastic enters the mold cavity. chip-forming. gel coats A term specific to composites, it refers to a quick- CNC Computer Numerical Control. setting coating applied to the internal surface of a mold to provide an improved, highly glossy, protective surface finish. CNC folding A process used to create three-dimensional hollow forms by the action of computer-controlled creasing gob A term used in glass blow molding that refers to the and folding of a flat sheet material. Think of a child’s metal sausage-shaped, measured quantity of molten glass before it pencil-case. enters the mold and is blown. Working and forming metal or glass at “green” state The wet, semihard physical state of a a temperature below that at which it recrystallizes, or, ceramic component before it has been fired. in simple terms, without the use of heat. See also work jig In production, a jig is a structure used to control or hardening. restrict the movement of a component or material while it is commodity polymers These have a lower mechanical being worked on, assembled, or glued. performance than engineering polymers (see below) and lathing Otherwise known as turning but generally used in include polypropylene and polyethylene. the context of working in metal. composites Materials that are made of two or more mandrel Often used in metal spinning to describe the solid ingredients. The term is generally used to refer to materials form against which the sheet of metal is spun to achieve the with advanced properties that are made from a combination desired shape. of polymer resins and fibers. matrix When using composites, the matrix is the material to crazing An imperfection in a ceramic glaze that appears as which the fibers are added—often a liquid polymer. a fine cracking. micron One thousandth of a millimeter. deep draw Refers to a component that has been produced by a long punch that draws the metal into a deep shaft. mold See die. Impact extrusion is an example of a process that produces a non-chip-forming cutting deep draw. A term used to describe cutting methods that do not result die The terms “die” and “mold” are virtually the same and in chips of material being formed. These methods are very refer to a form, generally made of steel, that is used as a clean and include, for example, laser or water-jet cutting, cavity into which material is added, and which imparts its where the material is blasted or vaporized leaving no “chips.” shape onto the component. See also tools.

LK016_P0282EDmakingIt2us.indd 282 16/09/2011 15:13 Glossary 283

outgasing A term used to describe the emission of a volatile tensile strength When a material is stretched so that the gas during the processing of plastics, for example in injection length increases and the cross-section decreases, tensile molding. There are many established ways of removing strength is the amount of stress that the material is able to these gases. withstand. parting lines The fine line that stands proud on the surface thermal expansion Most materials expand when heated of a component that is often left after molding. Essentially it and contract when cooled. Thermal expansion is defined as is where the two or more parts of a mold have separated. Also the ratio between increase in temperature and increase in known as witness lines. dimension of the material. postprocess operations Any process that takes place thermoplastics Together with thermosets (see below) the after the main production is referred to as “post.” Examples term is one of the main classifications for grouping plastics. include: post finishing, where surfaces might need to Unlike thermosets, thermoform plastics can be reheated and be cleaned up; and post forming, post working, or post- subsequently remolded. machining where a secondary process is used to complete thermosets Plastics that once formed cannot be reheated the component. These might include drilling a hole or remolded. Also known as thermosetting plastics. Compare or deburring. thermoplastics. pre-form Used predominantly in blow molding to describe tools A general term (also “tooling”) that refers to the part an injection molded, semiformed component before it has of the production setup that could loosely be described as been fully molded. A kind of product in its embryonic stage. a mold (see above). However, tooling is not necessarily the psi A unit of pressure that stands for pounds per square male or female mold itself, but the complete mechanism that inch. See also bar. is in direct contact with the material. It may refer to either a mold, cutters, or formers. re-entrant angles See undercuts. undercuts This is a very common term used in many forms of molding to describe details in a component that would refractory materials Materials with very high restrict that component’s removal from a mold. Also often temperature-resistance that are used in furnaces or kilns. referred to as re-entrant angles. Many ceramics are “refractories,” which is another way of describing these materials. witness lines See parting lines. risers A term used in metal casting to describe a shaft in the work hardening The best way of explaining this mold that acts as a reservoir from which molten metal can phenomenon is that when a piece of metal is bent (“worked”) be drawn to offset the shrinkage that takes place in metal continuously it becomes increasingly hard and difficult to casting once the metal cools and solidifies. See also runners. bend, and eventually it breaks. Annealing (see above) at regular intervals prevents this and allows for further working. runners The shaft into which metal is poured during See also cold working. casting. See also risers. sink marking This is a common, often easily solved, problem that occurs in injection molding. It is when plastic that needs to be formed into a flat surface exhibits a slight indent or depression, the “sinking.” This is often because of local shrinkage of the material within the component. solid-state forming An umbrella term used to describe the processing of materials usually at room temperature. Examples include impact extrusion and rotary swaging. This is the tapered piece of plastic that is left attached to a component as the result of injection or compression molding. It occurs where the plastic flowed into the mold from the nozzle. Evidence of where this has been cut off can often be seen in cheap moldings. substrate A term generally used to describe the surface material onto which a secondary layer of material is applied. It can be considered as something like the base material. tempering The purpose of tempering is to reduce the hardness of steel by relieving the stresses in the material. The process involves heating the steel to a temperature below the transformation range and then cooling it slowly in air.

LK016_P0282EDmakingIt2us.indd 283 16/09/2011 15:13 284 Index

blanking 59 (VPP) 234-5 decorative finishing techniques blow and blow molding, glass chairs 53 262-7, 279-81 Index 9, 12-13, 115, 120-3 Air-Chair 201 decorative metal screens 108 blow forming 76, 77 AP Stool 80 deep three-dimensional blow molding 12-13, 115, CI 248 forming, plywood 10-11, 83-5 127-8, 129-31 Extrusions 96-7 Demakersvan (Holland) 21-2 acid etching 163 blown film 12-13, 92-3 Gubi 83, 85 dental bracket, used in braces Acme Metal Spinning (USA) 57 blown glass 120 Laleggera range 181 222, 223 Acme Thunderer whistle 50, 51 Blumer, Riccardo 181, 182 Parupu 78 Desert Storm architectural Acme Whistles (UK) 50 body panels, bus 176 Pollock 138 panels 67 advanced technologies 239-59 Boontje, Tord 263 Prince 42 desktop printers 240-3 Air Switch flask lamp 116-7 boring 18 Seggiolina POP 178, 179 Diamonex 272 Air-Chair 201 Bosch 172 Sparkling 6, 130 Diamon-Fusion® 273 Alias (Italy) 181, 182 bottles spun carbon 158 diaphragm forming 72 alloys 44, 72 glass 120-3 chemical milling 10-11, 38-9 die cutting 10-11, 37, 40-1 backward impact extrusion Kikkoman 120 chemical polishing 276 die-pressing and sintering 168 146-8 plastic 6, 76, 115, 128, chemical vapor deposition 273 dinner tray 86 ceramic coating 270 130, 133 chip-forming processes 18, 59 dip coating 280 explosive forming 67-9 Sigg 146 chocolate Easter eggs 137, 139 dip molding 12-13, 134-6, 280 forging 187-9 bowls 29, 46 chocolate-box tray 64 direct extrusion see forward high-pressure die-casting Black Honey 246 Chorchoj, Olgoj 118 impact extrusion 219-21 mortar 27, 28 chrome plating 262, 279 Dixon, Tom 262 investment casting 224-7 paper 46 Cinderella table 21-2 drape forming 65 laser cutting 47 Brighton University (UK) 184 circumferencial winding 158 draping 53 metal injection molding broaching 20 closed-die forging 187-8, 190, 191 drilling 20 (MIM) 216-8 bronze 168-9 CNC Auto Motion (USA) 23 drop forging sand casting 228-30 bubble forming 70-1, 72 co-extrusion blow molding see closed-die forging superforming 70, 72 Bruni, Vetrerie (Italy) 124 127, 132-3 dry-bag pressing 172, 173 wire EDM (electrical bubble forming 70, 71, 72 CO2 silicate casting 228 DuPont™ 278 discharge machining) 44 Bunte, Amelie 143 cold isostatic pressing (CIP) DuraPulp 78, 79 Allwood, Julian 257 business card, Mikroman 38 14-15, 27, 30, 172-3 dynamic lathing 19, 26-8 ALPI (Italy) 84 Buxton, Sam 38 complex parts 194-237 aluminum, superforming composite materials E-Go laptop 214 10-11, 70-2 C1 chair 248 autoclave molding 156-7 edible menu 240 anodizing 279 CAD files 8, 19, 46, 192-3, 239, contact molding 154 Ekuan, Kenji 120 Apple design studio 104, 279 244, 246-7, 252 fiber-reinforcement 99, 100, electrical plug 174-5 Apple iMac aluminum stand calendering 12-13, 90-1 101, 102, 152, 154, 156, electroforming 12-13, 164-5 104 Cambridge University 257 158, 175 micro-moulds 14-15, 250-1 Apple iPod Shuffle 279 Campbell, Louise 42 filament winding 158 electromagnetic forming Apple Mini iPod 279 Cantu, Homaro 240 MuCell® injection molding 6, 10-11, 54-5 Arad, Ron 72, 279 car hood ornament, “Spirit of 203-5 electron-beam machining architectural mesh 108-9 Ecstasy” 224, 225 Pulshaping™ 12-13, 102-3 (EBM) 10-11, 24-5, 35 Aridion™ 269 carbides 44 pultrusion 99-101 electroplating 164, 169, 262, 265 Arola, Antoni 112 carbon, reinforcement fibers reaction injection molding electropolishing 265 Around the Roses table 262 152, 153 (RIM) 199-200, 211 enameling 281 autoclave molding 12-13, 156-7 carbon nanotubes 25 transfer molding 176 engineering components 216 automated CAD-driven case hardening 272 vacuum infusion process European Space Agency 270 machines 17 cavity forming 70-1 (VIP) 154-5, 176 Exjection® (Germany) 6, 12-13, cell phone cover 242 compression molding 14-15, 94-5 back pressure forming 71-2 centrifugal casting 12-13, 161-3 102, 172, 174-5, 207 expanded plastic foam backward impact extrusion centrifuging 161, 162 computer numerical control foam molding 14-15, 12-13, 146-8 Ceram Research (UK) 234 (CNC) cutting 10-11, 19, 178-80 Bakelite 174 ceramics 21-3, 43, 81 foam molding into plywood balloon 134 coating 270 concrete 244 shell 14-15, 180-3 balloon former 134 cold isostatic pressing (CIP) “contact forming” 69 reaction injection molding ballpoint pen, BIC® Cristal® 196 172-3 contact molding 12-13, (RIM) 14-15, 153, 199-200, 211 Barthes, Roland 196 compression molding 174 152-3, 207 expanded polypropylene 178, bath, “Loo” range 234 formers 134-5 continuous lengths of material 179, 180 bearings 169, 171 glazing 281 89-113 explosive forming 10-11, 67-9 bench, Berta Vilagrassa 265 hot isostatic pressing (HIP) contour crafting 14-15, 244-5 extrusion 6, 94, 96-8, 146, 203, bending 59 170-1 Cornerstone Research Group 205, 244 plywood 10-11, 80-2, injection molding (CIM) (USA) 255 extrusion blow molding 12-13, 113, 184 222-3 cross-laminating veneers 80-1 127, 132-3 Bengtsson, Mathias 158 jiggering and jollying 29-32 Curvy Composites (UK) 7, 87, 184 Extrusions chair/bench 96-7 Berta Vilagrassa bench 265 laser cutting 47 cutting, metal 59 beverage can, pull tab 59 pressure-assisted slip cutting tools 17 facing 18 BIC® (France) 196 casting 141, 234-5 Faraday, Michael 134 BIC® Cristal® ballpoint pen 196 sintering 168 David Design (Sweden) 228 Fiam Italia (Italy) 52 Bich, Marcel 196 slip casting 137, 140-2, 235 Davy, Sir Humphrey 164 fibers, reinforcement 99-101, bike, MN01 70 thick film metalizing 273 deburring 275 154, 156, 158, 175, 176, 199 binders 216-17 turning 26-8 decalization 277 fiber-reinforced plastics Black Honey bowl 246 viscous plastic processing decoration 212-5 99-101, 102, 152

LK016_P0282EDmakingIt2us.indd 284 16/09/2011 15:13 Index 285

filament winding 12-13, Gubi chair 83, 85 Jackson, Kathryn 257 242, 243 158-60, 255-6 hand lay-up molding 152, 154 Jack-stand 61 medical implants (hip-bone film insert molding hand-blown glass 12-13, 115, jars, glass 124-5 plate) 24 see in-mold decoration 116-7, 121 jiggering 10-11, 29-31 melamine 86, 87, 175 finishing techniques 6, 18, 260-80 handrail system, T-section 143 jollying 10-11, 29, 30, 32 menu, edible 240 decorative 262-7, 279-81 hard steels 44 Jordan, Malcolm 7 , 84, 184-5 metal injection molding (MIM) functional 268-81 metal injection molding Jouin, Patrick 248 14-15, 216-8 see also under (MIM) 14-15, 216-8 Metal Injection Mouldings Ltd individual entries Haunch of Venison (UK) 56, 97 Kami no Kousakujo (Japan) 46 (UK) 216 Fiskars (Finland) 209 Hay (Denmark) 42 Karkov, Simon 40 metals flat swaging 107 Heatherwick, Thomas 56, 96-7 kerf 34 backward impact extrusion Flexiform 234 helical winding 158, 159 Keronite® 270 146-8 flocking 163 “High Funk” table legs 228 Khoshnevis, Dr. Behrokh 244 case hardening 272 fluid forming high-energy-rate forming Kikkoman bottle 120 chemical milling 38-9 see hydroforming, metal see explosive forming Kikkoman Corporation (Japan) centrifugal casting 12-13, foam molding 14-15, 178-80 high performance alloys 44 120 161-3 into plywood shell 14-15, high temperature coatings 272 King Dick Tools (UK) 187 ceramic coating 270 180-3 high-density polyethylene knife, “Kyotop” range 170 CO2 silicate casting 228 see also reaction injection (HDPE) 128 knurling 18 cold isostatic pressing (CIP) molding (RIM) high-pressure die-casting Kolte, Olof 228 172-3 Ford Motor Company 177 14-15, 169, 219-21 Komplot 83 cutting 10-11, 18, 59-60 forging 14-15, 146, 167, 187-9 hip-bone plate 24 KX Designers 265 deburring 275 forward impact extrusion Holdcroft, Harold 236 Kyocera (Japan) 170 decorative finishes 263, 264 146, 147 hollow components, with thin Kyotop range, knife 170 electroforming 164-5 Foster, Norman 72 wall section 115-65 electromagnetic forming Franzheld, Robert 143 hot foil blocking 266 Laleggera range, chair 181 54-5 Fraunhofer Institute (Germany) hot isostatic pressing (HIP) lamp, Air Switch flask 116-7 electropolishing 265 26, 192 14-15, 27, 30, 169, 170-1, 222 lampshades forging 187-9 free internal pressure-formed Hudson, Joseph 50 Leonardo 112 free internal pressure- steel (“FIDU”) 10-11, 73-5 HVAC valve component 203 metalized copper finish 262 formed steel (“FIDU”) 10-11, Full Blown Metals (UK) 76 hydrodynamic machining Norm 69 40 73-5 functional finishing techniques see water-jet cutting Wednesday Light 263 galvanizing 275 268-81 hydroforming, metal 12-13, 143-5 lampworking glass tube 12-13, high-pressure die-casting furniture 6, 7 118-9 219-21 plywood 21-2, 80-5, 113, Ideal Standard (UK) 234 Lapalma (Italy) 80 hydroforming 12-13, 143-5 181-3 IDT Systems (UK) 212 laptop computers incremental sheet-metal sheet material 37 iMac aluminum stand, E-Go 214 forming 14-15, 57, 257-9 veneers 83, 85, 113, 181 Apple 104 VAIO 262 inflating 76-7 see also tables; chairs impact extrusion 146-7 laser cutting 10-11, 23, 25, investment casting 14-15, in-mold decoration 14-15, 30, 46-7 224-7 Galen, Marcel van 214 212-3, 268 laser engraving 264 laser cutting 47 galvanizing 275 Inclosia Solutions 214 laser-beam machining 46-7 machining 9, 18, 19 garden secateurs 209 incremental sheet- operations 18, 19, 20, 26, metal injection molding Gardone, Massimo 262 forming 14-15, 57, 257-9 118, 119 (MIM) 216-8 gas-assisted injection molding indirect extrusion see lemon juicer 231 milling 20 14-15, 153, 196, 197, 200, backward impact extrusion Leonardo lampshade 112 oxyacetylene cutting 48-9 201-2, 211 industrial craft 257 Levy, Ark 246 phosphate coatings 271 gas cutting industrial weaving 108 liquid-repellent coatings 269 pickling 277 see oxyacetylene cutting Industrial Origami® (US) London Underground 281 plasma-arc cutting 10-11, gas welding 6, 10-11, 61-3 Loo range, bath 234 25, 33-5 see oxyacetylene cutting inflated stainless steel pillows 76 lost-wax casting see powder coating 270 glass inflating metal 10-11, 76-7 investment casting powder forging 14-15, 190-1 blow and blow molding inflating wood 14-15, 184-6 Louis-Jensen, Toby 70 pre-crimp weaving 12-13, 12-13, 120-3 injection blow molding Ludvik, Gudmunder 80 108-11 blowing by hand 12-13, 6, 12-13, 127, 129-31 roll forming 104-5 115-19, 121 injection molding 6, 8, 14-15, machining 9, 10-11, 18-20 rotary swaging 12-13, 106-7 lampworking 12-13, 118-19 23, 94, 120, 137, 169, 176, Macor 19 sand casting 228-30 press and blow molding 177, 196-211 Magis (Italy) 130, 179, 201 sheet-metal forming 50-1 124-6 pre-form (bottle) 76-7, Maglica, Anthony 18 shot peening 274 pressing 12-13, 231-3 129-31 Maglite Instruments Inc. sintering 168, 190, 217, protective coatings 273 injection stretch molding (USA) 18 218, 252 roll forming 104 127, 129 Maglite® torch, Mini 18, 279 spinning 10-11, 56-8 sandblasting 267 inkjet printers/printing 7, 8, magnetic fields 54-5 superforming, aluminum sintering 168 14-15, 240-1, 242, 244, 262 Manzini, Ezio 260 10-11, 70-2 slumping 10-11, 52-3 insert molding 206-8 Mari, Enzo 178, 179 water-jet cutting 42-3 vitreous enameling 281 investment casting 14-15, 224-7 Marloes ten Bhömer (UK) 137 wire EDM (electrical GoreTex® 278 Ion-mask™ 269 Matchbox (UK) 219 discharge machining) 44-5 granite 23 iPod Mini, Apple 279 Matchbox “Lotus Europa” 219 microcellular foam 203, 204 graphics, application of 262, iPod Shuffle, Apple 279 Materialise (Netherlands) 246 micro-molding 250-1 265, 266, 268, 277, 280 i-SD system 268 Mathmos Design Studio (UK) 116 Miele 260, 263 gravity die-casting 220 Ito, Setsu and Shinobu 52 Matsui, Yoshiyuki 170 Mikroman business card 38 Gubi (Denmark) 83 Mcor Technologies Ltd (UK) milling 19, 20

LK016_P0282EDmakingIt2us.indd 285 16/09/2011 15:13 286 Index

Mimotec (Switzerland) 250 plasma-arc cutting 10-11, and foam molding 14-15, see also under individual Mini Maglite® torch 18 , 279 25, 33-5 180-3 processes Mining and Chemical Products plastic bottles 6, 76, 115, 130, 133 furniture 21-2, 80-5, 113, Reholz® (Germany) 83, 84, 85 Ltd (UK) 252-3, 254 plastics 236 181-3, 185 reinforced reaction injection mirrors 276 autoclave molding 156-7 inflating 184-6 molding (RIM) 199 MN01 bike 70 blow molding 12-13, 76, machining 21-2 reinforcement fibers 99, 100, Morrison, Jasper 201 115, 127-8 pressing 10-11, 86-7 101, 102, 152, 154, 156, 158, mortar 27, 28 blown film 12-13, 92-3 veneer cutting 112-13 175, 176, 199 Moto Restaurant (USA) 240 calendering 90-1 polar winding 158 Revelation World Cup molding, paper pulp 12-13, components 64 polishing 19 adjustable bike fork 2011 270 78-9, 149-51 contact molding 152-3 Pollock chair 138 Rexam (UK) 59 MuCell® injection molding die cutting 40-1 Polyactic acid (PLA) 78 robot transfer, insert molding 14-15, 203-5 dip molding 134-6, 280 Polycast Ltd (UK) 224 207 multicomponent molding Exjection® 94-5 polyethylene terephthalate RockShox 270 206-11 extrusion blow molding (PET) 41, 128, 129, 130, roll forming 12-13, 104-5 multishot injection 127, 132-3 131, 133 rotary cutting 112, 113 molding 209-11 fiber-reinforced 99-100, (PTFE) rotary swaging 12-13, 106-7 Mycalex 19 102, 152 see Teflon ® rotary transfer, insert molding Mykroy 19 filament winding 158-60, Potter & Soar (UK) 108 206 255-6 powder coating 270 rotational casting see nano-scale components 25, 251 foam molding 14-15, 178-80 powder forging 14-15, 190-1 rotational molding NASA 266 foam molding into plywood powder metallurgy 167, 168, rotational molding 12-13, 137-9 Naunheim, Karsten 143 shell 14-15, 180-3 170, 190, 252, 254 roto molding Neville & Sons (UK) 86, 87 gas-assisted injection precise-cast prototyping see rotational molding Newby, Stephen 72, 76 molding 196, 201-2 (pcPRO®) 14-15, 192-3 rough pulp molding 149 Newson, Marc 70, 72, 234 i-SD 268 pre-crimp weaving 12-13, 108-11 Royal Doulton (UK) 140, 236 Nextel 266 in-mold decoration press and blow molding 124-6 Rune, Claesson Koivisto 78 nibbling 59 212-3, 268 press forging 188, 191 Nichetto, Luca 262 injection molding 120, 127, press forming 59 Saloga, André 143 non-chip-forming processes 129-31, 137, 196-211, 214 pressing, plywood 10-11, 86-7 sample components 192 46-7, 59 insert molding 206-8 pressing glass 12-13, 231-3 sand casting 14-15, 228-30 nonstick coating 278 molded 203-4 pressure-assisted drain casting sandblasting 267, 274 Norm 69 lampshade 40 MuCell® injection molding 234 Santa & Cole (Spain) 112 Normann Copenhagen 203-5 pressure-assisted slip casting screen printing 264, 273, 277 (Denmark) 40 over-mold decoration 14-15, 141, 234-5 screw threads 18, 20, 147 214-15 pressure-bag forming 152, 153 screwdriver, Stanley DynaGrip open-die forging 187, 189 precise-cast prototyping pressure forming 65 Pro 206 over-mold decoration 14-15, (pcPRO®) 14-15, 192-3 pressure sintering 168 Seggiolina POP chair 178, 179 213, 214-5, 267 pultrusion 99-101 pressureless sintering 168, 169 selective laser sintering (SLA) oxyacetylene cutting 10-11, 33, roll forming 104-5 pressuring glass 14-1 14-15, 169, 247, 252-4 34, 35, 48-9 rotational molding 137-9 Prince chair 42 selective laser melting (SLM) oxygen cutting see sheet 90, 138 printers 7, 8, 14-15, 240-1, 242, 252-3 oxyacetylene cutting sintering 168 244, 262 self-healing coating 269 Oyster cards 273 Smart Mandrels™ 255-6 protective coatings 273 semicentrifugal casting 161, 162 stereolithography (SLA) pull tab, beverage can 59 Serra, Richard 105 P2i 269 246-9 pulp paper 10-11, 78-9, 112, shape-memory technology 255 packaging sublimation dye printing 149-51 shearing 59 die cutting 41 262 Pulshaping™ 12-13, 102-3 sheet glass 52-3 injection molded 197 thermoforming 64-6 pultrusion 12-13, 99-101 sheet material, products made sheet material 37 thermoplastics 95, 124, 197, Pultrusion Dynamics, Inc. from 37-87 painting, surfaces 260 201-2, 207, 211, 270 (USA) 102 sheet-metal forming 10-11, 50-1 paper thermoset 174, 176, 177, punching 59, 60, 105 shell casting 228, 229 calendering 90 207 PVC sheet 90, 91 shoes, rotational molded 137 laser cutting 46 thick-film metalizing 273 shot peening 274 molding 12-13, 78-9, 149-51 transfer molding 176-7 radio frequency identification shrink-wrapping 280 recycling 149, 242 vacuum infusion process (RFID) tags 273 Sigg drinks bottle 146, 148 paper-based rapid prototyping (VIP) 154-5, 177 ram method, wire EDM 44 sinter forging 242-3 vacuum metalizing 262 rapid prototyping 7, 14-15, 17, see powder forging Parupu chair 78 vapor metalizing 276 23, 79, 169, 193, 246, 254, 273 sintering 14-15, 168-9, 170, 190, pen, BIC® Cristal® ballpoint 196 water-jet cutting 42-3 paper-based 242-3 217, 218, 252 perforating 59 plastic-state forming 194 reaction injection molding slicing 112 pestle 26-28 plate, Wedgwood® 29 (RIM) 14-15, 153, 199-200, 211 slip casting 12-13, 27, 30, 137, phosphate coating 271 plating, surfaces 260 reaming 20 140-2, 235 photo-etching Plopp stool 73 recycling 19, 23 slumping glass 10-11, 52-3 see chemical milling plug, electrical 174-5 aluminum 60, 72 Small Precision Tools (USA) photo-quality printers 161 plug-assisted forming 65 glass 53, 117, 233 222, 223 pickling 277 plywood 112 ink cartridges 241 Smart Mandrels™ 14-15, 239, pipes 161 bending 10-11, 80-2, 113, metals 41, 51, 63 255-6 Pizza Kobra light 279 184 over-molded products 267 Sodra Pulp Labs (Sweden) 78, 79 plasma-arc spraying 274 deep three-dimensional paper 149, 242, 243 solid-state forming processes plasma electrolytic oxidation forming 10-11, 83-5 plastics 41, 65, 100, 173, 280 167-93 (PEO) 270 plywood 81 Sony 262

LK016_P0282EDmakingIt2us.indd 286 16/09/2011 15:13 Index and Acknowledgments 287

Southern California, University tables 53, 183 Wade Ceramics (UK) 26, 27, 134 Acknowledgments of 244 Around the Roses 262 Wanders, Marcel 6, 130 Thanks to Dani Salvadori, who South Carolina, Medical Cinderella 21-2 water injection technology has helped champion this University of 8, 241 Toki side table 52 (WIT) 196-8 idea since its inception. Many spanner 187 tampo printing 265 water-jet cutting 10-11, 35, 42-3 thanks also to Ishbel Neat, spark eroding see wire EDM teacup, Old Roses range 236 wax patterns 224-7 Lucy Macmillan, and Jennifer (electrical discharge teapot, Wedgwood® 140 Wedgwood (UK) 7 Hudson for their help with machining) Teflon® 168, 278 plate 29 the laborious task of chasing spark machining see wire textiles, calendering 90 teapot 140 permissions for the images. As EDM (electrical discharge thermal cutting 33, 48-9 Wednesday Light 263 always, a massive thank you machining) thermal spray 271 wet etching see acid etching to “my team” for this project: spark plug 172 thermoforming 10-11, 64-6 wet-bag pressing 172, 173 Hema Vyas, Hayley Ho, Anna spark sintering 168 paper pulp 149, 150 whistles 50 Frohm, and the biggest thank Sparkling Chair 6, 130 thermoplastic elastomers (TPE) Acme Thunderer 50, 51 you to Daniel Liden, who spinning, metal 10-11, 56-8 207, 209 Whiteread, Rachel 134 has been many things in the Spiral paper bowl 46 thermoplastics 95, 124. 153, wire EDM (electrical discharge writing of this book, including “Spirit of Ecstasy,” car hood 197, 201-2, 207, 211, 270 machining) 10-11, 44-5 researcher and adviser. Thanks ornament 224, 225 thermo-reversible gel 240-1 wood also to James Graham for spray lay-up molding 152 thermoset plastics 174, 176, inflating 184-6 his wonderful illustrations; spun carbon chair 158 177, 207, 270 laminated 87 to Roger Fawcett-Tang for stamping 59, 60, 61 thermoset resins 103, 152, 153 turning 26 making this book so visually “standoff forming” 69 thick-film metalizing 273 see also plywood; striking; Xavier Young not Stanley DynaGrip Pro thin wall section, hollow veneers; trees only for his photography but screwdriver 206 components with 115-65 also for his inspired ideas Stanley Tools (UK) 206 threading 18, Xylan 278 and continued collaboration; stationary spindle swaging three-dimensional printing to Russell Marshal for his 106–07 240, 242-3 Zientz, Kristof 143 technical appraisal; and to steel 25, 27, 35 titanium 39, 44, 47, 48, 49, Zieta, Oskar 73, 74, 75 Alan Baker who, after almost case hardening 272 171, 173 zirconia ceramic knife blades 20 years, is still my “materials centrifugal casting 162-3 Toki side table 52 170, 171 and process man”—it is a chemical milling 38-9 torch, Mini Maglite® 18, 279 pleasure to have been one electromagnetic forming Toyota 258, 259 of your students. 54-5 transfer molding 14-15, 153, electron-beam machining 176-7 A really big thank you to all (EBM) 24-5 trees 112 at Laurence King Publishing, forging 187-9 see also plywood; particularly Jo Lightfoot and free internal pressure- veneers; wood Jessica Spencer. formed (“FIDU”) 10-11, 73-5 true centrifugal casting 161, 162 hard 44 tubes 54, 143, 161 A special thanks to my young hot isostatic pressing (HIP) Tulip (Netherlands) 214 sons Theo and Jerome, whose 170-1 tungsten 39, 168 constant joy provided me with hydroforming 143-5 turning 10-11, 18, 20, 26-8, 30 the motivation to deal with the incremental sheet-metal two-shot molding see frequent lack of sleep they both forming 57, 257-9 multicomponent molding so generously encouraged. inflating 76 Lastly, thank you to my wife laser cutting 47, 74 upset forging 188 Alison who after 20 years metal injection molding urine bottle, disposable 149 continues to be my supreme (MIM) 216-8 creative inspiration, partner, metal spinning 56-7 vacuum-bag molding 152-3 and motivator. Here’s to the plasma-arc cutting 33-5 vacuum casting 247 next 20 years, my love. pre-crimp weaving 111 vacuum cleaner 260, 263 wire EDM (electrical vacuum forming 64 discharge machining) 44-5 vacuum infusion process (VIP) steel junction, handrail system 12-13, 154-5, 177 143 vacuum metalizing 262 stereolithography (SLA) 14-15, VAIO laptop computers 262 239, 243, 246-9 Valeo (Germany) 203 Ströh, Anette 143 vapor metalizing 276 structural-reaction injection varnishing 169 molding (S-RIM) 199 vases, thin-walled 118 sublimation dye printing 262 veneers 86, 112, 113 suede coating 266 cross-laminating 80-1, 184 Superform Aluminium (UK) 70 cutting 12-13, 83, 84, 112-3 superforming, aluminum furniture 83, 85, 113, 181 10-11, 70-2 Verhoeven, Jeroen 21 Vernacare 149 see finishing techniques viscous plastic processing Sykes, Charles Robinson 224 (VPP) 14-15, 236-7 vitreous enameling 281 T-section, handrail system 143 volatile organic compounds table legs, “High Funk” 228 (VOCs) 268, 270, 271

LK016_P0282EDmakingIt2us.indd 287 16/09/2011 15:13 288 Picture Credits

Picture Credits GmbH. Go-Ahead London Fabrication Technologies The author and publisher 86 right Neville UK Plc. 179 Seggiolina Pop, Magis, (CRAFT), University of would like to thank all 94 Photograph by Ida Riveros photo by Carlo Lavatori. Southern California. contributors who have kindly 96 Heatherwick Studio Magis SPA, Z.I. Ponte Tezze 246 Black_Honey.MGX by Arik provided images for use in this 97 Peter Mallet – Via Triestina Accesso E, Levy for .MGX by Materialise. book. Every effort has been 99 © Exel Composites Plc. 30020 Torre di Mosto (VE), 248 top left/right Patrick Jouin made to contact copyright 101 Photographs by Daniel Italy. Tel: +39 0421 319600, ID – Solid C1 – Patrick Jouin holders, but the publishers Liden, taken at RBJ Plastics Fax: +39 0421 319700, studio. would be pleased to correct in Rickmansworth, [email protected] 248 bottom left Patrick Jouin any errors or omissions in www.rbjplastics.com 181 & 183. Photographs ID – Solid C1 – Patrick Jouin any subsequent edition. 104 right Courtesy of Apple courtesy of Alias studio. Inc. Photographer: 184. & 186. Photographs 248 bottom right Patrick Jouin All illustrations by James Doug Rosa courtesy of Malcolm Jordan. ID – Solid C1 – Thomas Duval. Graham 108-9. Permission for LKP to 192 Fraunhofer Institute 250 Courtesy of Mimotec. Photographs by Chris Lefteri: use image has been granted Material and Beam 253 Photograph courtesy pp. 20, 28, 31, 32, 66, 104 by Potter & Soar Ltd. who Technology IWS, Germany. of Renishaw plc – left, 110, 142, 206 are part of the Aughey 196 Courtesy of BIC® Cristal® www.renishaw.com Photographs by Xavier Young: Group of companies. 201 Air-chair designed by 255 Courtesy of Cornerstone 18, 24, 29, 40, 50, 64, 99, 112 Designer: Antoni Arola. Jasper Morrison. Air-chair, Research Group. 108–09, 120, 130 top, 134 Photograph by Carme Masià. Magis, photo by Tom Vack. 257 & 258 Photograph by right, 140, 149, 170, 172, 174, 116 left Mathmos Airswitch Magis SPA, Z.I. Ponte Tezze Martin McBrien. Courtesy 187, 209, 219, 231, 236, 275 Flask Lamp is a trademark – Via Triestina Accesso E, of Dr. Julian Allwood and and a patented technology 30020 Torre di Mosto (VE), University of Cambridge 18 By permission of Mag owned by Mathmos— Italy. Tel: +39 0421 319600, Dept. of Engineering Instrument, Inc. MAG- www.mathmos.com. Fax: +39 0421 319700, 262 (Sublimation Dye Printing) LITE and MAGLITE are 116 right Courtesy of Kosta [email protected]. Alessandro Paderni; registered trademarks of Boda. Photographer Vassilis 203 Courtesy Gianni di Liberto (Vacuum Metallizing) left: Mag Instrument, Inc. Theodorou 206 Stanley UK Sales Ltd. Courtesy Tom Dixon right: 21–22 DEMAKERSVAN 118 left Photograph by Goran 212 Courtesy IDT Systems Ida Riveros 24 Courtesy of Arcam AB. Tacevski. The vases were 214 Courtesy of Tulip 263 (Flocking) Courtesy Miele 26 Wade Ceramics Ltd. developed with Mr. Karel Computers. & Cie KG; (Acid Etching) 29 WWRD UK LTD. Krajc, Head of the Technology 216 Courtesy of Metal Injection Courtesy Studio Tord Boontje 33 Reproduced by permission Department of glassworks at Mouldings Ltd. 265 Courtesy Franc Fernandez of TWI Ltd. Kavalier Sázava. 219 Courtesy Mattel. LOTUS, and kxdesigners 38 left Sam Buxton, Mikro 118 right Photographs by Craig EUROPA and the Europa car 267 Adrian Niessler and Kai Man Off Road, 2002, Martin and Brian Godsman, design are the intellectual Linke 95lx35wx40h mm. Image property of Scott Glass Ltd. property of Group Lotus plc. 269 (Self-healing coating) courtesy of the artist. 120 Courtesy of KIKKOMAN N.B. The rights of Group Courtesy Hyundai; 38 right Sam Buxton, CORPORATION. Lotus plc extend to the (Liquid-Repellent Coatings) Mikro Man Player, 2002, 123 Photographs courtesy of design of the car embodied in Courtesy p2i 95lx35wx40h mm. Image Beatson Clark Ltd. the toy featured in work and 270 (Ceramic Coating) courtesy of the artist. 124 Bruni Glass SPA copyright. the trade marks LOTUS and Courtesy of SRAM LLC; 40 Normann Copenhagen. Photograph by Bruni Glass EUROPA. Group Lotus owns (Powder Coating) Courtesy 42 Design: Louise Campbell. SPA. no rights in the toy itself nor COLNAGO Manufacturer: Hay 130 bottom Courtesy Marcel in the photographs of the toy 274 Courtesy 46 Fuminari Yoshitsugu Wanders to be reproduced in the book. WHEELABRATOR GROUP 50 Acme WhistleCo. 134 left Wade Ceramics Ltd. 222 Photograph Ida Riveros 279 (Chrome Plating) 52 Setsu & Shinobu ITO. FIAM 135 Courtesy of Diptech. 224 Reproduced with Amendolagine e Barracchia Italia Spa. 137 & 138 Courtesy Marloes permission of Rolls-Royce Fotografi; (Anodizing) 56 Peter Mallet ten Bhömer Motor Cars Limited. The Courtesy VERTU 58 Heatherwick Studio 140 Courtesy of Wedgwood Spirit of Ecstasy, Rolls- 281 (Ceramic Glazing) 59 Rexam Beverage Can 143 & 144 top. Courtesy of Royce name, and logo are Courtesy Porzellan Europe & Asia Darmstadt University of registered trade marks and Manufaktur Nymphenburg 61 & 62 Courtesy of Industrial Technology are owned by Rolls-Royce www.nymphenburg.com; Origami, Inc. 146 & 147. Sigg Switzerland AG Motor Cars Limited or (Vitreous Enamelling) 67 & 68 Courtesy 3D-Metal 149 Courtesy of Vernacare used under license in some Xavier Young Forming B.V. 154 Courtesy of Polyworx. jurisdictions. Photograph by 70 Image Marc Newson Infusion of the permission of Polycast. 73 & 74 All images Zieta Southernwind 100’ 226 Photographs by Prozessdesign carbon/epoxy sailing permission of Polycast. 76 Created by Stephen Newby/ yacht; technology 228 Courtesy of Olof Kolte Full Blown Metals. Image designed and 234 Marc Newson Ltd taken by Joe Hutt. implemented by 236 WWRD UK LTD. 78 Courtesy Sodra Pulp Labs Polyworx BV. 240 Homaro Cantu/ Moto 80 Lapalma s.r.l., via E. 158 Courtesy of Mathias Restaurant, Chicago Majorana 26, 35010 Bengtsson. 242 Models produced by Mcor on Cadoneghe (PD), Italy. 159 Photographs courtesy the Matrix 300 file provided 83 Design: Komplot Design/ of Goodrich Crompton by Paul Hermon Queen’s Poul Christiansen & Boris Technology Group. University and photographed Berlin. Production: Gubi, 170 © KYOCERA. by Cormac Hawley Denmark. 172 NGK Spark Plugs (UK) Ltd. 244 Photographs courtesy of the 85 Photographs by Reholz 176 By permission of Centre for Rapid Automated

LK016_P0282EDmakingIt2us.indd 288 16/09/2011 15:13