Guest Lecture On Advanced Manufacturing Processes

Prepared By Prof. Shinde Vishal Vasant Assistant Professor Dept. of Mechanical Engg. NDMVP’S Karmaveer Baburao Thakare College of Engg. Nashik Contact No- 8928461713 E mail:- [email protected] Website:- www.vishalshindeblog.wordpress.com

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 1 Grinding Process • Grinding is a material removal and surface generation process used to shape and finish components made of metals and other materials. • The precision and surface finish obtained through grinding can be up to ten times better than with either turning or milling.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 2 Grinding • Grinding is a surface finishing operation where very thin layer of material is removed in the form of dust particles. • Thickness of material removed is in range of 0.25 to 0.50 mm. • Tool used is a wheel.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 3 Types Of Grinding Machine

• There are many forms of grinding, but the four major industrial grinding • Surface grinding • Cylindrical grinding • Centerless grinding • Internal grinding • Electrochemical grinding • Belt grinder • Bench grinder • Tool and cutter grinder • Gear grinder

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 4 Major Advantages And Applications Of Grinding

Advantages • Dimensional accuracy • Good surface finish • Good form and locational accuracy applicable to both hardened and unhardened material Applications • Surface finishing • Slitting and parting • De-scaling , De-burring • Stock removal (abrasive milling) finishing of flat as well as cylindrical surface • Grinding of tools and cutters and re-sharpening of the same.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 5 Materials • Most used in industry are synthetic. Aluminum oxide is used in three quarters of all grinding operations, and is primarily used to grind ferrous metals. • Next is , which is used for grinding softer, non-ferrous metals and high density materials, such as cemented carbide or ceramics. • Superabrasives, namely cubic boron nitride or "CBN" and diamond, are used in about five percent of grinding. Hard ferrous materials are ground with "CBN", while non-ferrous materials and non-metals are best ground with diamond.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 6 Standard Shapes Of Grinding Wheels

• Straight wheel • Cylinder • Tapered • Recessed one side • Straight cup • Recessed both sides • Flaring cup • Dish • Saucer • Mounted wheels

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 7 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 8 Selection Of Grinding Wheel

For grinding a job the right grinding wheel is to be selected. The selection of a grinding wheel will depend on the following factors. • Material to be ground • Amount of stock to be removed • Finish required • Area of contact • Wheel speed • Work speed • Personal factor • Method of cooling

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 9 Standard Marking System for Aluminum-Oxide and Silicon-Carbide Bonded Abrasives

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 10 Standard Marking System for Cubic-Boron- Nitride and Diamond Bonded Abrasives

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 11 Grinding Fluid The Grinding fluid serves three main functions : • Reduces Wheel wear. • Cools the w/p. • Flushes away the chips.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 12 Grinding Process

Grinding is an abrasive process that uses a grinding wheel as the cutting tool.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 13 Surface Grinding

Surface grinding uses a rotating abrasive wheel to remove material, creating a flat surface.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 14 Surface Grinding

• It is machine basically used to grind flat surface. • Job is mounted to a table which moves longitudinally as well as in transverse direction. • Manual feed or power feed. • Work piece is clamped to the table by operating magnetic chuck. • Required grade of grinding tool is fixed to spindle. • Grinding operation is carried out be operating both table traverse wheel and vertical feed hand wheel.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 15 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 16 Types Of Surface Grinding Machine

Basically there are four different types of surface grinding machines characterised by the movement of their tables and the orientation of grinding wheel spindles as follows:

• Horizontal spindle and reciprocating table • Vertical spindle and reciprocating table • Horizontal spindle and rotary table • Vertical spindle and rotary table

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 17 Surface grinding • In surface grinding, the spindle position is either horizontal or vertical, and the relative motion of the work piece is achieved either by reciprocating the work piece past the wheel or by rotating it. The possible combinations of spindle orientations and work piece motions yield four types of surface grinding processes illustrated in the figure

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 18 Horizontal And Vertical Grinding Machines

• This machine may be similar to a milling machine used mainly to grind flat surface. However, some types of surface grinders are also capable of producing contour surface with formed grinding wheel.

A: rotation of grinding wheel B: reciprocation of worktable C: transverse feed D: down feed 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 19 Cylindrical Grinding • It is a process of grinding curved surfaces. • Surface may be straight or tapered. • Work piece is mounted on two centers, one is tailstock centre and the other is headstock centre. • Head stock center may or may not revolve.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 20 Cylindrical Grinding

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 21 Cylindrical Grinding

• In this operation, the external or internal cylindrical surface of a work piece are ground. In external cylindrical grinding (also center-type grinding) the work piece rotates and reciprocates along its axis, although for large and long work parts the grinding wheel reciprocates. • In internal cylindrical grinding, a small wheel grinds the inside diameter of the part. The work piece is held in a rotating chuck in the headstock and the wheel rotates at very high rotational speed. In this operation, the work piece rotates and the grinding wheel reciprocates.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 22 External Cylindrical Grinding

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 23 Internal Cylindrical Grinding

Internal grinding is used to grind the internal diameter of the workpiece. Tapered holes can be ground with the use of internal grinders that can swivel on the horizontal.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 24 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 25 Plunge Cut Grinding

Infeed (Plunge) Grinding is used to grind work pieces which have projections or shoulders, multiple diameters or other irregular shapes which preclude the use of through feed grinding. For example :- Grinding of crank shaft.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 26 Centerless Grinding Machine

• It is used to grind curved surface work piece which are long and slender. • Work piece rests on a work-rest blade and is backed by a second wheel called as regulating wheel. • Grinding wheel pushes the work piece down the work-rest blade against the regulating wheel. • Center less grinding differs from centered grinding operations in that no spindle or fixture is used to locate and secure the work piece. • The work piece is secured between two rotary grinding wheels, and the speed of their rotation relative to each other determines the rate at which material is removed from the work piece.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 27 Center less Grinding

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 28 Thread Grinding

Figure - Thread grinding by (a) traverse and (b) plunge grinding.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 29 Electrochemical Grinding

• The wheels and work piece are electrically conductive. • Wheels used last for many grindings - typically 90% of the metal is removed by electrolysis and 10% from the abrasive grinding wheel. • Capable of producing smooth edges without the burrs caused by mechanical grinding. • Does not produce appreciable heat that would distort work piece. • Decomposes the work piece and deposits them into the electrolyte solution. The most common electrolytes are sodium chloride and sodium nitrate.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 30 Applications

• Grinding turbine blades • Grinding honeycomb metals for aerospace application • Sharpening hypodermic needles • Machining carbide cutting-tool inserts • ECG is used to remove surface defects from parts where excessive material removal and residual stresses are undesired, such as re-profiling locomotive gears

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 31 Electrochemical Grinding

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 32 Specification Of Grinding Wheel

i. Abrasives ii. Bond iii. Grit/grain size iv. Grade v. Structure of wheels

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 33 Specification of Grinding wheel

• Specification of a grinding wheel ordinarily means compositional specification. Conventional abrasive grinding wheels are specified encompassing the following parameters. – The type of grit material – The grit size – The bond strength of the wheel, commonly known as wheel hardness – The structure of the wheel denoting the porosity i.e. the amount of inter grit spacing – The type of bond material – other than these parameters, the wheel manufacturer may add their own identification code prefixing or suffixing (or both) the standard code. 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 34 Dressing Of Grinding Wheel • When the sharpness of grinding wheel becomes dull because of glazing and loading, dulled grains and chips are removed (crushed or fallen) with a proper dressing tool to make sharp cutting edges and simultaneously, make recesses for chips by properly extruding to grain cutting edges. Thus, these operations are for the dressing. • Dressing is the process of breaking away the glazed surface so that sharp particles are again presented to the work.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 35 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 36 Grinding-Wheel Dressing

Figure (a) Forms of grinding-wheel dressing. (b) Shaping the grinding face of a wheel by dressing it with computer control. Note that the diamond dressing tool is normal to the surface at point of contact with the wheel. 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 37 Truing And Dressing Of Grinding Wheel

• Truing is the act of regenerating the required geometry on the grinding wheel, whether the geometry is a special form or flat profile. Therefore, truing produces the macro-geometry of the grinding wheel.

• Truing and dressing are commonly combined into one operation for conventional abrasive grinding wheels, but are usually two distinctly separate operation for super abrasive wheel.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 38 Difference Between Truing And Dressing

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 39 Balancing Of Grinding Wheel

• Due to high rpms, unbalanced grinding wheels may have negative effects both on quality and productivity. • It is essential to control the vibrations induced in the machine as an effect of the imbalance of mechanical parts and the rotating grinding wheel. • To enable the full potential of modern tool grinding machines and to produce efficiently according to today`s standards, it is absolutely essential to use balanced tools.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 40 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 41 Safety Precautions

• Wear goggles for all grinding machine operations. • Check grinding wheels for cracks before mounting. • Never operate grinding wheels at speeds in excess of the recommended speed. • Never adjust the work piece or work mounting devices when the machine is operating. • Do not exceed recommended depth of cut for the grinding wheel or machine. • Remove work piece from grinding wheel before turning machine off. • Use proper wheel guards on all grinding machines. • On bench grinders, adjust tool rest 1/16 to 1/8 inch from the wheel.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 42 Types Of Super Finishing Processes

Honing.

Lapping. Burnishing.

Buffing. Polishing

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 43 • Honing is a finishing process, in which a tool called hone carries out a combined rotary and reciprocating motion while the work piece does not perform any working motion. Most honing is done on internal cylindrical surface, such as automobile cylindrical walls. • Honing is an abrasive machining process that produces a precision surface on a metal work piece by scrubbing an abrasive stone against it along a controlled path. • Honing uses a special tool, called a honing stone or a hone, to achieve a precision surface. The hone is composed of abrasive grains that are bound together with an adhesive. Generally, honing grains are irregularly shaped and about 10 to 50 micrometers in diameter (300 to 1,500 mesh grit). Smaller grain sizes produce a smoother surface on the workpiece.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 44 Work piece Honning (Pipe) Setup Tool or Hone

Coolant

Machine Bed

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 45 Honning Tool

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 46 Advantages And Disadvantages

ADVANTAGES DISADVANTAGES • Low cost simple fixturing • Accuracy in thin walled parts • Honing is a slow process. • Accuracy in long bores • Horizontal honing may • Honing maintains the original bore create oval holes unless the centreline work is rotated or supported. • Bores are corrected with least possible amount of material • If the workpiece is thin, removal even hand pressure may • Material removal in all materials cause a slightly oval hole. regardless of hardness. • Any degree of surface finish in a part. • High stock removal rates ( up to 12 times faster than internal grinding) 03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 47 Applications • finishing of cylinders for internal combustion engines • air bearing spindles • Gears

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 48 Super finishing /Micro honing

• Super finishing is a micro finishing process that produces a controlled surface condition on parts which is not obtainable by any other method. The operation which is also called ‘micro stoning’ consist of scrubbing a stone against a surface to produce a fine quality metal finish.

• The process consists of removing chatter marks and fragmented or smear metal from the surface of dimensionally finished parts.

• As much as 0.03 to 0.05 mm of stock can be efficiently removed with some production applications, the process becomes most economical if the metal removal is limited to 0.005 mm

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 49 Super finishing

Figure:- Schematic illustrations of the super finishing process for a cylindrical part. (a) Cylindrical mircohoning, (b) Centerless microhoning.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 50

• In lapping, instead of a bonded abrasive tool, oil-based fluid suspension of very small free abrasive grains (aluminum oxide and silicon carbide, with typical grit sizes between 300 and 600) called a lapping compound is applied between the work piece and the lapping tool.

• The lapping tool is called a lap, which is made of soft materials like copper, lead or wood. The lap has the reverse of the desired shape of the work part. To accomplish the process, the lap is pressed against the work and moved back and forth over the surface.

• Lapping is sometimes performed by hand, but lapping machines accomplish the process with greater consistency and efficiency.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 51 Lapping

Figure (a) Schematic illustration of the lapping process. (b) Production lapping on flat surfaces.(c) Production lapping on cylindrical surfaces.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 52 Advantages:-

1.Increase wear life of part.

2.Improve accuracy and surface finish.

3.Improve surface flatness.

4.Provide better seals and eliminate need for gaskets.

Applications:- Lapping is used to produce optical lenses, metallic bearing surfaces, gauges, and other parts requiring very good finishes and extreme accuracy.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 53 Lapped Objects

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 54 Burnishing

• Burnishing is the plastic deformation of a surface due to sliding contact with another object. Visually, burnishing smears the texture of a rough surface and makes it shinier. Burnishing may occur on any sliding surface if the contact stress locally exceeds the yield strength of the material. • Burnishing is a Super-finishing process.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 55 SETUP

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 56 Advantages • Mirror Finish in One Pass, Accurate Sizing, Close Tolerances, Eliminates Lapping & Honing • Improved Metallurgical Properties - Work Hardened Surface, Increase in fatigue strength, • No Additional Machine Investment - attachable to any Standard Already Present in the Shop • Long Tool Life No Operator Skill Required Low Torque & Power Requirements Maximum Parts Interchangeability

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 57 Applications

• Bright burnishing tools are being used in sectors like Automobile, Aircraft, Defense, Spacecraft, Railways, Textile, Machine Tool, Motors and Pump Industry, Hydraulic and Pneumatic Farm Equipment, Home Appliances etc., and areas where close tolerance and superior surface finish is required.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 58 Polishing

• Polishing is a finishing operation to improve the surface finish by means of a polishing wheel made of fabrics or leather and rotating at high speed. The abrasive grains are glued to the outside periphery of the polishing wheel. • Polishing operations are often accomplished manually. • Polishing is the process of creating a smooth and shiny surface by rubbing it or using a chemical action, leaving a surface with a significant specular reflection • Polishing may be used to enhance and restore the looks of certain metal parts or object on cars and other vehicles, handrails, cookware, kitchenware, and architectural metal.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 59

Setup

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 60 Advantages & Disadvantages

ADVANTAGES DISADVANTAGES

• Gives a natural appearance with a • A messy process, requiring high gloss and sheen. additional work to clean up. • Produces a relatively durable finish. • If oxalic acid is included in the • Never requires stripping. powder, it can cause etching or • Can be applied with a standard low blistering of marble and speed weighted floor machine. limestone depending on the skill • If oxalic acid or oxalate is included of the person using it. in the powder, it will remove fine to • Requires equipment (i.e., a floor medium scratches. machine, wet vac, mop, mop • Only done periodically, not daily or bucket, etc.). weekly. • Compounds composed of aluminum oxide will not etch floor.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 61 Buffing • Buffing is a finishing operation similar to polishing, in which abrasive grains are not glued to the wheel but are contained in a buffing compound that is pressed into the outside surface of the buffing wheel while it rotates. As in polishing, the abrasive particles must be periodically replenished. • As in polishing, buffing is usually done manually, although machines have been designed to perform the process automatically. • Buffing wheels are made of discs of linen, cotton, broad cloth and canvas • Buffing is also used to manufacture light reflectors.

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 62 Buffing

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 63 Summery of Abrasive machining processes

03/10/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK 64