Grinding: Definition, Advantage, Disadvantage, Application, Specification, Type`s of Grinding

 

Grinding: Definition,  Advantage, Disadvantage, Application, Specification, Type`s of Grinding

It is a material cutting process which engages an abrasive tool whose cutting elements are grains of abrasive material known as grit. Grinding is the most common form of abrasive machining. These grits are characterized by sharp cutting points, high hot hardness, and chemical stability and wear resistance. The grits are held together by a suitable bonding material to give shape of an abrasive tool. Grinding can be compared with milling with an infinite number of cutting edge.

 

ADVANTAGES OF GRINDING OPERATION:

·            This can produce a high surface finish with accurate can obtain.

·            This can machine hard materials.

·            This operation can be done with less pressure applied on work.

·            It can obtain highly accurate dimensions.

·            It can work at high temperature also.

·            Speed of cutting can be done by this process.

·            In grinding abrasive particles, they are self-sharpened action.

·            This can operate for complex things also.

·            Smooth surface can obtain.

 

 

DISADVANTAGES OF GRINDING OPERATIONS:

·            Required tool is high cost.

·            Process is also a costly one.

·            It cannot remove the high amount of material, it only removes a little amount.

·            For removing the required amount from work it consumes more time.

·            You should work carefully, because imperfect contact may lead to damages.

 

Application of Grinding

·        Surface finishing

·        Slitting and parting

·        Descaling, debarring

·        Stock removal (abrasive milling)

·        Finishing of flat as well as cylindrical surface

·        Grinding of tools and cutters and resharpening of the same.

 

Grinding Specification

 

Grinding Ratio

The grinding ratio or G ratio is defined as thee cubic mm of stock removed divided by the cubic mm of wheel lost. The G ratio is a measure of grinding production and reflects the amount of work a wheel can do during its useful life.

 

Grade

The worn out grit must pull out from the bond and make room for fresh sharp grit in order to avoid excessive rise of grinding force and temperature. A soft wheel should be chosen for grinding hard material. A hard wheel should be chosen for grinding soft material.

 

Structure

The structure should be open for grinding wheels engaged in high material removal to provide chip accommodation space. The space between the grits also serves as pocket for holding grinding fluid. Dense structured wheels are used for longer wheel life, for holding precision forms and profiles.

 

Glazing

With continuous use a grinding wheel becomes dull with the sharp abrasive grains becoming rounded. This condition of a dull grinding wheel with worn out grains is termed as glazing.

 

Loading

Some grinding chips get lodged into the spaces between the grits resulting in a condition known as loaded wheel. Loading is generally caused during the grinding of soft and ductile materials. A loaded grinding wheel cannot cut properly and need dressing.

 

Dressing

Dressing is the conditioning of the wheel surface which ensures that grit cutting edges are exposed from the bond and thus able to penetrate into the workpiece material. n dressing attempts are made to splinter the abrasive grains to make them sharp and free cutting and also to remove any residue left by material being ground.

 

Truing

Truing is the act of regenerating the required geometry on the grinding wheel. Truing is also required on a new conventional wheel to ensure concentricity with specific mounting system.

 

Creep Feed Grinding

This machine enables single pass grinding of a surface with a larger down feed but slower table speed than that adopted for multi‐pass conventional surface grinding. In creep‐feed grinding, the entire depth of cut is completed in one pass only using very small in‐feed rates.

 

Cylindrical Grinding

Center‐type cylindrical grinding is commonly used for producing external cylindrical surfaces. The grinding wheel revolves at an ordinary cutting speed, and the workpiece rotates on centers at a much slower speed. Grinding machines are available in which the workpiece is held in a chuck for grinding both external and internal cylindrical surfaces.

 

Centerless Grinding

Centerless grinding makes it possible to grind both external and internal cylindrical surfaces without requiring the workpiece to be mounted between centers or in a chuck. Two wheels are used. The larger one operates at regular grinding speeds and does the actual grinding. The smaller wheel is the regulating wheel. It is mounted at an angle to the plane of the grinding wheel. The regulating wheel controls the rotation and longitudinal motion of the workpiece and usually is a plastic‐ or rubber‐bonded wheel with a fairly wide face.

 

Lapping

Lapping is basically an abrasive process in which loose abrasives function as cutting points finding momentary support from the laps.

 

Honing

Honing is a finishing process, in which a tool called hone carries out a combined rotary and reciprocating motion

while the workpiece does not perform any working motion. Most honing is done on internal cylindrical surface, such as automobile cylindrical walls. The honing stones are held against the workpiece with controlled light pressure. The honing head is not guided externally but, instead, floats in the hole, being guided by the work surface.

 

Buffing

Buffing is a polishing operation in which the workpiece is brought into contact with a revolving cloth wheel that has been charged with a fine abrasive, such as polishing rough. The wheels are made of disks of linen, cotton, broadcloth, or canvas, and achieve the desired degree of firmness through the amount of stitching used to fasten the layers of cloth together.