DOCSLIB.ORG

Numerical Control Fabrication: Its Nature and Application

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Numerical Control Fabrication: Its Nature and Application MICHAEL L. HAGLER NUMERICAL CONTROL FABRICATION: ITS NATURE AND APPLICATION Numerical control is a tool that frees the craftsman from the mechanical control of equipment in much the same way that the calculator and computer freed the engineer from the burden of manual calcula­ tions. This article presents background information that describes the nature of numerical control and highlights several applications of numerical control fabrication at APL. INTRODUCTION machine's motions and functions needed to fabricate a In order to understand the application of numerical workpiece contained in the numerical control program. control and computer numerical control fabrication, it It is important to understand that numerical control is valuable to review the nature of these processes that is a concept of machine control, not a manufacturing have become so commonplace in metalworking facilities. method. While it is important to understand what nu­ Numerical control is the operation of a machine by merical control is, it is equally critical to understand what a series of coded instructions comprised of alphanumeric it is not. Numerical control is not an electronic brain; characters. The instructions are translated into electri­ not even computer numerical control at the current state cal pulses or other output signals that activate motors of technology can approach the capabilities of the hu­ and other devices to control a machine. For machine man brain. Numerical control cannot think, evaluate, tools, numerical control commands range from positive judge, discern, or show any true adaptability. It is pos­ positioning of the spindle in relation to the workpiece, sible, with advanced computer numerical control, to have to auxiliary functions such as selecting a tool station or predetermined logic trees or alternatives that allow in­ a turret, or controlling the speed and direction of spin­ correct instructions or unplanned occurrences such as dle rotation. Numerical control commands can include tool breakage to cause machine actions to override the functions such as coolant control, dimension sensing, program instructions. The basic process, however, re­ and tolerance verification. The commands, compiled and mains that of (a) a programmer developing instructions logically organized to direct a machine tool in a specific that are encoded and (b) the machine control unit ex­ task, comprise a numerical control part program. The ecuting them. program, once developed, can be stored and executed A numerical control machine tool has design param­ at a later time to obtain exactly the same results as the eters that determine its capabilities; adding numerical first time it was used. control will not provide machining capabilities that are The program is executed by feeding the data into a not already present. The fact that a numerical control machine control unit. A common medium for data is installed on a machine with a 7-horsepower spindle transfer is punched paper tape, the method used at APL. in no way changes the spindle's capability to drive a cut­ Early machine control units for numerical control were ting tool. When properly applied, however, numerical hard-wired units where all the features of the controller control will permit greater efficiency in using that spin­ had circuits that were developed for their execution. dle by machining during a greater percentage of the fab­ There was limited flexibility or ability to modify features rication cycle. This holds true for other machine and no editing capability for the program at the machine capabilities. For example, if the maximum table travel control unit. As computer technology developed and mi­ is 30 inches, numerical control will not electronically pro­ crocomputer capabilities became less costly and more vide a 4O-inch travel range, but numerical control will tolerant of fabrication environments, computer numer­ allow more efficient use of the 30-inch movement. ical control equipment became the standard in the fabri­ A fundamental requirement of numerical control is cation industry. Today, the terms have blended until they the ability to communicate in the language of the ma­ are almost interchangeable in usage, with numerical con­ chine control unit. A machine control unit can only pro­ trol being the generic term for both. cess or act on certain limited symbolic codes that have specific meanings. The programmer must understand the THE NATURE OF THE PROCESS codes and their precise meaning to the machine control Numerical control is revolutionary because the respon­ unit and then must limit communication to that frame­ sibility for controlling a machine is now shared between work. Creative thinking to use the full capability of a a craftman's skill and the documentation of the machine and the machine control unit and learning how 260 Johns Hopkins APL Technical Digest, Volume 7, Number 3 (1986) to communicate (encode effectively) in the machine con­ TYPES OF NUMERICAL CONTROL trol unit's language comprise the art of effective numer­ PROGRAMMING ical control. There are several reasons why numerical control Just as computers have evolved from the vacuum tube equipment is effective in all fabrication environments, mainframe to the powerful personal computer, an anal­ including both the high volume of industry and the low ogous evolution is taking place in the related area of nu­ volume of the experimental environment at APL. merical control programming. There are now multiple With numerical control, multifunctional machines be­ appropriate methods for developing numerical control come more practical. A machining center, for example, programs. APL is developing the capabilities for using can mill, drill, and bore. Most of the installed equip­ the most appropriate and cost-effective method for each ment has multiple tools stored on the machine, ready project; three modes of programming are used to pro­ for automatic insertion in the machine spindle as re­ vide the appropriate level of sophistication required to quired to perform multiple operations with only one fabricate a part (Fig. 1). setup of the workpiece. The average part does not have The most sophisticated programming mode at APL to be transferred between machines for different pro­ uses computer-aided design, an interactive graphics sys­ cesses, which reduces the cycle time for the fabrication tem that can display color geometry and toolpaths in of the part, an extremely critical consideration at APL. three dimensions. The complexity of the geometry can Numerical control can produce a part at a consistent range from simple straight lines and arcs to complex rate of speed. In conventional machining, it has been curves and surfaces. The numerical control capabilities observed that the rate at which the machinist removes of the computer-aided design system include profiling, material decreases as the part draws closer to comple­ automatic pocketing, point-to-point milling, surface mill­ tion. This is a reaction to the realization that an error ing, drilling, tapping, and various turning and punch­ at a late point in the fabrication process will void all ing operations. previous activity. With numerical control machining, the There are three advantages in using the computer­ program can be verified graphically on a cathode ray aided design system for numerical control programming. tube at the controller and can then be machined in met­ The first is the ability to program the machine to cut al at a constant rate, because the program has been veri­ difficult shapes and contours without performing man­ fied before the first cutting tool has touched the material. ual calculations. The programmer can display three­ In a numerical control program, the experience and dimensional part geometry at any desired viewing an­ judgment of the craftsman are preserved indefInitely, al­ gle. He can then interactively drive a graphically dis­ lowing the program to be used repeatedly with identical played tool along that geometry. The second advantage and predictable results. Numerical control should be is that the programmer can verify the toolpath by sim­ viewed as an extension, not a replacement, of the crafts­ ply displaying the tool following the geometry. All neces­ man. Numerical control serves as a catalyst that relieves sary geometry and toolpaths are displayed as they are the craftsman of the responsibility for turning handles defmed. The third and primary advantage is that the part and moving a workpiece and allows him to apply his geometry has been defmed for the programmer, who has true skill: the determination of the fabrication process. direct access to the computer-aided design engineering Computervision: three-dimensional CAD/CAE Mainframe CAM NC design station design programming database station Microcomputer-based: two-dimensional r------, Engineering Microcomputer drawing NC programming station Figure 1-The three methods of nu­ merical control programming used Conversational: at APL. CAD = Computer-aided design CAE = Computer-aided engineering CAM = Computer-aided manufacturing NC = Numerical control Johns Hopkins APL Technical Digest, Volume 7, Number 3 (1986) 261 Hagler - Numerical Control Fabrication: Its Nature and Application drawing created by the designer. These advantages al­ low the programmer to do complex work more quickly and reliably. ~--------R1--------------~~ The types of work on which computer-aided design capability is of greatest benefit include (a) complex ~-------R2----------~ curves, such as a series of
Load more

Recommended publications
  • Numerical Control (NC) Fundamentals
    Lab Sheet for CNC Laboratory Department of Production Engineering and Metallurgy Prepared by: Dr. Laith Abdullah Mohammed Production Engineering – CNC Lab Lab Sheet Numerical Control (NC) Fundamentals What is Numerical Control (NC)? Form of programmable automation in which the processing equipment (e.g., machine tool) is controlled by coded instructions using numbers, letter and symbols - Numbers form a set of instructions (or NC program) designed for a particular part. - Allows new programs on same machined for different parts. - Most important function of an NC system is positioning (tool and/or work piece). When is it appropriate to use NC? 1. Parts from similar raw material, in variety of sizes, and/or complex geometries. 2. Low-to-medium part quantity production. 3. Similar processing operations & sequences among work pieces. 4. Frequent changeover of machine for different part numbers. 5. Meet tight tolerance requirements (compared to similar conventional machine tools). Advantages of NC over conventional systems: Flexibility with accuracy, repeatability, reduced scrap, high production rates, good quality. Reduced tooling costs. Easy machine adjustments. More operations per setup, less lead time, accommodate design change, reduced inventory. Rapid programming and program recall, less paperwork. Faster prototype production. Less-skilled operator, multi-work possible. Limitations of NC: · Relatively high initial cost of equipment. · Need for part programming. · Special maintenance requirements. · More costly breakdowns. Advantages
    [Show full text]
  • Enrolled Joint Resolution
    2009 Assembly Joint Resolution 67 ENROLLED JOINT RESOLUTION Relating to: commending MAG Giddings and Lewis on its sesquicentennial. Whereas, the company now known as MAG Giddings & Lewis was founded in 1859 in Fond du Lac, Wisconsin, as a small machine shop that produced parts and provided repairs for Wisconsin's sawmills and gristmills; and Whereas, over time, the business expanded its shop to include a gray iron foundry, the first in Wisconsin, and became the Novelty Iron Works, with a continued emphasis on sawmill machinery; and Whereas, in the 1870s and 1880s, the Novelty Iron Works continued its expansion into manufacturing industrial steam engines for clients across the United States; and Whereas, in the 1870s and 1880s, changes in ownership brought the Novelty Iron Works under a partnership of Colonel C. H. DeGroat, George Giddings, and O. F. Lewis, leading to a new name, DeGroat, Giddings & Lewis; and Whereas, in 1895, DeGroat sold his interest in the partnership to Giddings and Lewis, and the company was incorporated as the Giddings & Lewis Manufacturing Company, commonly known as Giddings & Lewis; and Whereas, as Wisconsin's lumber industry began to decline in the late 1890s and early 1900s, Giddings & Lewis began to concentrate on manufacturing machine tools, including lathes, gear cutting equipment, shapers, planers, drills, grinders, and even shell lathes for the British Ministry of Munitions during World War I; and Whereas, Giddings & Lewis entered into a sweeping modernization program during the 1920s and 1930s, went public
    [Show full text]
  • What Is a CNC Machine? CNC : Computerised Numerical Control
    What is a CNC Machine? CNC : Computerised Numerical Control (Computer + Numerical Control) • Numerical control is a programmable automation in which process is controlled by Numbers, Letters, and symbols. • CNC Machining is a process used in the manufacturing sector that involves the use of computers to control machine tools like lathes, mills and grinders. 1 Why is CNC Machining necessary? • To manufacture complex curved geometries in 2D or 3D was extremely expensive by mechanical means (which usually would require complex jigs to control the cutter motions) • Machining components with high Repeatability and Precision • Unmanned machining operations • To improve production planning and to increase productivity • To survive in global market CNC machines are must to achieve close tolerances. 2 Ball screw / ball bearing screw / recirculating ballscrew Mechanism • It consists of a screw spindle, a nut, balls and integrated ball return mechanism a shown in Figure . • The flanged nut is attached to the moving part of CNC machine tool. As the screw rotates, the nut translates the moving part along the guide ways. Ballscrew configuration • However, since the groove in the ball screw is helical, its steel balls roll along the helical groove, and, then, they may go out of the ball nut unless they are arrested at a certain spot. 3 • Thus, it is necessary to change their path after they have reached a certain spot by guiding them, one after another, back to their “starting point” (formation of a recirculation path). The recirculation parts play that role. • When the screw shaft is rotating, as shown in Figure, a steel ball at point (A) travels 3 turns of screw groove, rolling along the grooves of the screw shaft and the ball nut, and eventually reaches point (B).
    [Show full text]
  • DRAFT – Subject to NIST Approval 1.5 IMPACTS of AUTOMATION on PRECISION1 M. Alkan Donmez and Johannes A. Soons Manufacturin
    DRAFT – Subject to NIST approval 1.5 IMPACTS OF AUTOMATION ON PRECISION1 M. Alkan Donmez and Johannes A. Soons Manufacturing Engineering Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 ABSTRACT Automation has significant impacts on the economy and the development and use of technology. In this section, the impacts of automation on precision, which directly influences science, technology, and the economy, are discussed. As automation enables improved precision, precision also improves automation. Followed by the definition of precision and the factors affecting precision, the relationship between precision and automation is described. This section concludes with specific examples of how automation has improved the precision of manufacturing processes and manufactured products over the last decades. 1.5.1 What is precision Precision is the closeness of agreement between a series of individual measurements, values, or results. For a manufacturing process, precision describes how well the process is capable of producing products with identical properties. The properties of interest can be the dimensions of the product, its shape, surface finish, color, weight, etc. For a device or instrument, precision describes the invariance of its output when operated with the same set of inputs. Measurement precision is defined by the International Vocabulary of Metrology [1] as the "closeness of agreement between indications obtained by replicate measurements on the same or similar objects under specified conditions." In this definition, the "specified conditions" describe whether precision is associated with the repeatability or the reproducibility of the measurement process. Repeatability is the closeness of the agreement between results of successive measurements of the same quantity carried out under the same conditions.
    [Show full text]
  • MCIS Direct Numerical Control for NX CAM
    MCIS Direct Numerical Control for NX CAM Connect NX CAM output directly to CNC machines Benefits Summary • Reduce NC data NX™ CAM software uses direct numerical control (DNC) connections from management costs for the Siemens’ Motion Control Information System (MCIS) to provide CNC file shop floor control to the shop floor. By directly linking CNC machines to NX CAM files, • Leverage user-friendly DNC enables NC programmers, shop floor managers, and machine tool interface to manage NC operators to easily organize, manage and transfer the correct NC programs to programs specified machines. • Reduce setup times • Automate NC program transfer to the machine tool • Keep NC data safe and backed up • Use Siemens’ SINUMERIK controllers without any additional hardware • Scalable to production requirements Connecting NX CAM data to the shop floor DNC system for transfer to CNC machines. NX machining and manufacturing solutions combine to ensure that parts are manufactured on-time and to specification by helping planning and production departments to work together more efficiently with the right data. The MCIS-DNC system can be configured to automatically transfer NC program files posted directly from NX CAM to the proper machine tools on the network. This gaurantees that the right NC program is always loaded on the right machine. Automatically route NX CAM data to the shop floor Using MCIS-DNC Explorer to manage You can generate enhanced NC programs from NX CAM that include special NC programs and related files on the instructions the DNC system can use to automatically route programs to shop floor. specified machines and operators on the shop floor.
    [Show full text]
  • ME 440: Numerically Controlled Machine Tools Outline
    Outline – Introduction ME 440: Numerically Controlled Machine Tools • Basic Definitions – Machine Tools – Precision Engineering Introduction • Historical Developments • Numerical Control Assistant Prof. Melik Dölen • Direct Numerical Control Department of Mechanical Engineering • CtNilCtlComputer Numerical Control • Distributed Numerical Control Middle East Technical University – Flexible Manufacturing Systems Chapter 1 ME 440 2 Definition of Machine Tool Conventional Machine Tools • Milling Mac hine • A machine used for sculpturing metal and • Lathe other substances to the desired form. • Drilling/Boring Machine • A machine system utilized for producing • Shaper/Planer machine par ts an d e lemen ts. • Grinding Machine •A machine tool is a powered mechanical • Filing Machines device, typically used to fabricate metal • Sawing Machines comppyonents of machines by the selective removal of metal. Chapter 1 ME 440 3 Chapter 1 ME 440 4 Non-traditional Machine Tools Machining Accuracy • Electro-Discharge Machine • Wire EDM • Plasma Cutter • Electron Beam Machine • Laser Beam Machine Chapter 1 ME 440 5 Chapter 1 ME 440 6 Ultraprecision Machining History of Machine Tools Processes • 1770: Simple production machines • Single-point diamond and mechanization – at the turning and CBN beggginning of the industrial cutting revolution. • 1920: Fixed automatic mechanisms • Abrasive/erosion and transfer lines for mass processes (fixed and production. free) • 1945: Machine tools with simple automatic control, such as plug • Chemical/corrosion board controllers. processes (etch- • 1952: Invention of numerical control machining) (NC). Chapter 1 ME 440 7 Chapter 1 ME 440 8 History of Machine Tools (Cont’ d) History of Machine Tools (Cont’d) • 1961: First commercial Industrial robot. • 1972: First CNCs introduced. • 1978: Flexible manufacturing system (FMS); contains CNCs, robots, material transfer system.
    [Show full text]
  • Outlook for Numerical Control of Machine Tools 28 ’65
    L 2*. 3 ' W37 OUTLOOK FOR NUMERICAL CONTROL OF MACHINE TOOLS 28 ’65 A Study of a Key Technological Development in Metalworking Industries Bulletin No. 1437 UNITED STATES DEPARTMENT OF LADOR W. Willard Wirtz, Secretary BUREAU OF LABOR STATISTICS Ewan Clague, Commissioner Digitized for FRASER http://fraser.stlouisfed.org/ Federal Reserve Bank of St. Louis OTHER BLS PUBLICATIONS ON AUTOMATION AND PRODUCTIVITY Manpower Planning to Adapt to New Technology At an Electric and Gas Utility--A Case Study (Report No. 293, 1965). Techniques used to facilitate manpower adjustments. Covers three technological innovations affecting more than 1,900 workers. Case Studies of Displaced W orkers (Bulletin 1408, 1964), 94 pp. , 50 cents. Experiences of workers after layoff. Covers over 3, 000 workers from five plants in different industries. Technological Trends in 36 Major American Industries, 1964, 105 pp. Out of print, available in libraries. Review of significant technological developments, with charts on employment, production,and productivity. Prepared for the President's Advisory Committee on Labor-Management Policy. Implications of Automation and Other Technological Developments: A Selected Annotated Bibliography (Bulletin 1319-1. 1963), 90 pp. , 50 cents. Supplement to bulletin 1319, 1962, 136 pp. , 65 cents. Describes over 300 books, articles, reports, speeches, conference proceedings, and other readily available materials published prim arily between 1961 and 1963. Industrial Retraining Programs for Technological Change (Bulletin 1368, 1963), 34 pp. Out of print, available in libraries. A study of the performance of older workers based on four case studies of industrial plants. Impact of Office Automation in the Internal Revenue Service (Bulletin 1364, 1963), 74 pp.
    [Show full text]
  • Manufacturing Glossary
    MANUFACTURING GLOSSARY Aging – A change in the properties of certain metals and alloys that occurs at ambient or moderately elevated temperatures after a hot-working operation or a heat-treatment (quench aging in ferrous alloys, natural or artificial aging in ferrous and nonferrous alloys) or after a cold-working operation (strain aging). The change in properties is often, but not always, due to a phase change (precipitation), but never involves a change in chemical composition of the metal or alloy. Abrasive – Garnet, emery, carborundum, aluminum oxide, silicon carbide, diamond, cubic boron nitride, or other material in various grit sizes used for grinding, lapping, polishing, honing, pressure blasting, and other operations. Each abrasive particle acts like a tiny, single-point tool that cuts a small chip; with hundreds of thousands of points doing so, high metal-removal rates are possible while providing a good finish. Abrasive Band – Diamond- or other abrasive-coated endless band fitted to a special band machine for machining hard-to-cut materials. Abrasive Belt – Abrasive-coated belt used for production finishing, deburring, and similar functions.See coated abrasive. Abrasive Cutoff Disc – Blade-like disc with abrasive particles that parts stock in a slicing motion. Abrasive Cutoff Machine, Saw – Machine that uses blade-like discs impregnated with abrasive particles to cut/part stock. See saw, sawing machine. Abrasive Flow Machining – Finishing operation for holes, inaccessible areas, or restricted passages. Done by clamping the part in a fixture, then extruding semisolid abrasive media through the passage. Often, multiple parts are loaded into a single fixture and finished simultaneously. Abrasive Machining – Various grinding, honing, lapping, and polishing operations that utilize abrasive particles to impart new shapes, improve finishes, and part stock by removing metal or other material.See grinding.
    [Show full text]
  • Machine Code Glossary for Machining Centers
    Machine Code Glossary for Machining Centers What is G-Code? G-code is the common name for the most widely used numerical control (NC) programming language. Used primarily in automation, it is part of computer-aided engineering. G-code is also known as “G programming language”. In basic terms, G-code is a language in which people tell computerized machine tools what to make and how to make it. The "how" is defined by instructions on where to move to (direction of travel), how fast to move (rapid or controlled feedrate) and through what path to move (linear, circular, etc). The most common example is that, within a machine tool, a cutting tool is moved according to these instructions through a toolpath, cutting away excess material to leave only the finished workpiece. The same concept also applies to non-cutting tools, such as forming or burnishing tools and to measuring probes that validate the results. Commonly Used G Codes for Machining Centers G00 = Linear move (Rapid) G01 = Linear move (Feed) G02 = Circular move (interpolation) CW G03 = Circular move (interpolation) CCW G04 = Dwell time G10 = Zero offset shift G11 = Zero offset shift (cancel) G17 = XY plane selection G18 = ZX plane selection G19 = YZ plane selection G20 = Check for Inch mode G21 = Check for MM mode G28 = Return to reference point G29 = Return from reference point G30 = Return to 2nd, 3rd (etc.) reference point G40 = Cutter (diameter or radius) compensation off G41 = Cutter (diameter or radius) compensation to the left of the programmed path (climb) G42 = Cutter (diameter
    [Show full text]
  • CNC (Computer Numerical Control) Technologist/Specialist Location
    CNC (Computer Numerical Control) Technologist/Specialist Location: Sydney, NS Term: Permanent, Full-Time (Morning, Day, Evening, Flexible Hours) Anticipated Start Date: As Soon As Possible About the Organization Established in 2001, Protocase Inc is a rapidly expanding company that focuses on combining advances in software with advanced manufacturing techniques to offer unique custom manufacturing to the engineering, design, and research industries. Using the expertise and dedication of 130 employees (and counting), Protocase is proud to have a client base of more than 12,000 customers throughout North America and around the globe. Customers include Boeing, L3, Raytheon, Google, Apple, Microsoft, NASA, MIT and many more. To learn more about the company, visit http://www.protocase.com. About the Opportunity: Protocase is currently seeking a dedicated and experienced CNC Machining Technologist/Specialist to join our Production team in the fast-paced CNC Machining department in Sydney (Cape Breton), Nova Scotia. Our customers – engineers, designers and scientists – depend on Protocase to quickly and accurately CNC machine custom enclosures, panels and parts. Our CNC Machining equipment includes 3- and 5-axis milling machines, CNC Router, and CNC turning. As a member of the busy CNC team, you will help operators and programmers to optimize jobs, solve problems and improve processes, along with performing CNC programming tasks yourself. You will also assist our CNC Machining Specialist with troubleshooting equipment problems and repairing
    [Show full text]
  • Design and Implementation of G-Code Interpreter Based on QT
    2016 International Conference on Electrical Engineering and Automation (ICEEA 2016) ISBN: 978-1-60595-407-3 Design and Implementation of G-Code Interpreter Based on QT Guang-he CHENG1, Shuai ZHAO2,* and Rui-rui SUN1 1Shandong Computer Science Center (National Supercomputer Center in Jinan), Shandong Provincial Key Laboratory of Computer Networks, Jinan 250014, Shandong, China 2Qilu University of Technology, Jinan 250353, Shandong China *Corresponding author Keywords: Open CNC system, G code interpreter, SQLite database, Qt4. Abstract. This paper introduces a design of G code interpreter based on Qt. Firstly, it introduces the overall structure of the G code interpreter design. It introduces the regular expression as the tool of lexical, grammatical and semantic analysis, and introduces the SQLite database which is used to store the processing data. And then it explains the realization of the interpretation of the G code. Under the Qt4 environment, we develop the graphics applications, it not only has the module interface friendly, simple operation, easy transplant and a good human-computer interaction, but also has very high engineering application value. Introduction Compared with the traditional numerical control system, the embedded open CNC system has the advantages of small volume, low cost, low power consumption and stable system[1]. In the embedded system software, Qt/Embedded as a cross-platform GUI toolkit, which directly through the Qt API and Linux I/0 interaction, has a higher operating efficiency. The C++ class mechanism, who encapsulates the corresponding operation functions, plays a protective role to prevent the destruction of external data that caused by the instability[2]. The program written in Qt has good portability and wide adaptability.
    [Show full text]
  • Study Unit Toolholding Systems You’Ve Studied the Process of Machining and the Various Types of Machine Tools That Are Used in Manufacturing
    Study Unit Toolholding Systems You’ve studied the process of machining and the various types of machine tools that are used in manufacturing. In this unit, you’ll take a closer look at the interface between the machine tools and the work piece: the toolholder and cutting tool. In today’s modern manufacturing environ ment, many sophisti- Preview Preview cated machine tools are available, including manual control and computer numerical control, or CNC, machines with spe- cial accessories to aid high-speed machining. Many of these new machine tools are very expensive and have the ability to machine quickly and precisely. However, if a careless deci- sion is made regarding a cutting tool and its toolholder, poor product quality will result no matter how sophisticated the machine. In this unit, you’ll learn some of the fundamental characteristics that most toolholders have in common, and what information is needed to select the proper toolholder. When you complete this study unit, you’ll be able to • Understand the fundamental characteristics of toolhold- ers used in various machine tools • Describe how a toolholder affects the quality of the machining operation • Interpret national standards for tool and toolholder iden- tification systems • Recognize the differences in toolholder tapers and the proper applications for each type of taper • Explain the effects of toolholder concentricity and imbalance • Access information from manufacturers about toolholder selection Remember to regularly check “My Courses” on your student homepage. Your instructor
    [Show full text]