GRINDINGSUBMITTED BY AVINASH SNEHI (1214340049)ME-1 3rd YEAR

INTRODUCTION TO GRINDING PROCESS

• The Grinding process is used to produce a high surface finish with a close tolerance and for machining hard materials.

• The process is a variation of polishing and uses abrasive materials held together by an adhesive in the form of a solid wheel.

Purposes for GRINDING

• Removal of surplus material• Production of high surface finishes• Machining very hard materials

GRINDING WHEELS

• A grinding wheel consists of abrasive particles and bonding material. The bonding material holds the particles in place and establishes the shape and structure of the wheel.

• The wheel is generally made from a matrix of coarse particles pressed and bonded together to form a solid circular shape,various profiles and cross sections are available depending on the uses for the wheels.

GRINDING WHEEL

GRINDING WHEELS

FUNCTIONS OF A GRINDING WHEEL

• To remove materials from a workpiece• Each grains acts as a cutting tool• It is a cheap formation process• The only self sharpening cutting tool• Considered as a abrasive machining

ABRASIVES

• Abrasives are the intended for actual cutting action hence they are the hard substances.

• Abrasives are classified as• Aluminium Oxides• Ceramic• Silicon carbide• Super Abrasive-DIAMOND• Tungsten Carbide

Bond

• It is a material used as GLUE to hold the abrasive grains together.Bond has no cutting action.The bonding materials commonly used are

• Metal• Resin• Rubber• silicate

TYPES OF GRINDING WHEEL

GRINDING WHEEL WEAR

• Grinding wheel wear is an important consideration because it adversly affects the shape and accuracy of ground surfaces as in the case with cutting tools.

TYPES OF WEAR

• Attritious Wear• Grain Fracture• Bond Fracture

ATTRITIOUS WEAR

• The cutting edges of a sharp grain become dull.• Wear are caused by the interaction of the grain with the

workpiece involving both physical and chemical reactions.

• These reactions involve diffusion,chemical degradation or decomposition of the grain.

• Attritious wear is low when the two materials are chemically inert with respect to each other.

• The more the inert the materials,the lower will be the tendency of reaction.

• This wear based on the reactivity of the grain and the workpiece and their relative mechanical properties such as hardness and toughness.

GRAIN FRACTURE

Because abrasive grains are brittle,their fracture in grinding are important.• If the wear is excessive,the grain become dull.• Grinding become inefficient and produces undesirably

high temperatures.• New sharp cutting edge are produced continuously during

grinding.

BOND FRACTURE

• The strength of bond is a significant parameter in grinding.• If the bond is too strong sharp grain along the circumference of

the grinding wheel can begin to the contact of workpiece thus process becomes insufficient.

• If the bond is too weak the grain will dislodged easily,wear rate is of wheel is increases then dimensional accuracy becomes difficult.

GRINDING MACHINES AND OPERATIONS

• A grinding machine is a machine tool used for producing very fine finishes or making very light cuts using an abrasive wheel as the cutting device.

• A distinguishing feature of grinding machines is the rotating abrasive tool.

• Grinding machine is employed to obtain high accuracy along with very high class of surface finish on the workpiece.

CATEGORIES OF GRINDING MACHINE

1. Surface Grinding2. Cylindrical Grinding3. Internal Grinding4. Centre Grinding5. Centerless Grinding

SURFACE GRINDING

• Surface grinding is an abrasive machining process in which the grinding wheel removes material from the plain flat surfaces of the workpiece.

• the spindle position is either horizontal or vertical.• the relative motion of theworkpiece is achieved either by

reciprocating the workpiece past the wheel or by rotating it.

CYLINDRICAL GRINDING

• In this operation, the external or internal cylindrical surface of a workpiece are ground. In external cylindrical grinding (also center-type grinding) the workpiece rotates and reciprocates along its axis although for large and long workparts the grinding wheel reciprocates.

• In internal cylindrical grinding, a small wheel grinds the inside diameter of the part. The workpiece is held in a rotating chuck in the headstock and the wheel rotates at very high rotational speed. In this operation, the workpiece rotates and the grinding wheel reciprocates.

CENTRELESS GRINDING

• Centerless grinding is a process for continuously grinding cylindrical surfaces in which the workpiece is supported not by centers or chucks but by a rest blade. The workpiece is ground between two wheels. The larger grinding wheel does grinding, while the smaller regulating wheel, which is tilted at an angle regulates the velocity of the axial movement of the workpiece.

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