ABRASIVES

ABRASIVES

An abrasive is a material, often a mineral that is used to shape or finish a work piece through rubbing which leads to part of the work piece being worn away. While finishing a material often means polishing it to gain a smooth, reflective surface which can also involve roughening as in satin, matte or beaded finishes. Abrasives are extremely commonplace and are used very extensively in a wide variety of industrial, domestic, and technological applications. This gives rise to a large variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding. 

1.     Grit or grain:

It indicates the size of the abrasive grains used in making a wheel.

·        Coarse wheels are used for fast removal of materials and for soft and ductile materials.

·        Fine grain wheels are used to grind hard and materials.

2.     Grade: 

It refers to the tenacity or hardness with which the bind held the cutting points.  It is denoted by the 'A' -softest and 'Z'-the hardest hard wheels are recommended for soft   materials and soft wheels are recommended for the hard materials.

3.     Structure or grain spacing:

The structure refers to the number of cutting edges per unit area of wheel face as well as to the number and size of void spaces between grains & denoted by numbers. Soft, tough and ductile materials and heavy cuts require an open structure where as hard and brittle materials and finishing cuts require a dense structure.