Industrial Abrasives

Abrasives are materials having a comparatively higher hardness and are used to shape other materials by grinding or abrasive action. These materials are used as loose grains, as grinding wheels, or as coated abrasives, coated on either cloth or paper (sandpaper being the most common example).

Abrasive products find a wide range of application in the industries including, but not limited to, grinding and polishing glass, cleaning and machining metals, cutting metals, glass, cement etc., grinding logs for paper pulp. Abrasives are also used to manufacture products like brake lining, non-slip flooring required in certain conditions, etc.

Abrasives are harder than the material that it is used to polish and this difference in hardness is what makes the abrasives work. Traditionally, various minerals were used as abrasives, typically those having hardness of 7 or more, on the Moh’s Scale of Hardness. Nowadays, many synthetic stones and other materials prepared artificially are used as abrasives in various applications. Diamond is a commonly used abrasive in various industrial applications, due to its high level of hardness. Various minerals that are used as abrasives are either crushed, or are already found in the powdered from, the grain size of which ranges from 1m to 2mm (1000micron=1mm).

Factors deciding how quickly a substance is abraded include:
Relative difference in hardness between two substances.
Grain size and its matrix- larger grains will cut faster as well as deeper.
The force at contact- more force will obviously mean more abrasion.
Type of lubricant or a coolant used.

Some of the naturally occurring abrasives are Calcite, Emery, Novaculite, Pumice, Rouge, and Sand. Some like Diamond and Zirconia Alumina are found in nature, but are also extensively manufactured synthetically. Other artificially prepared abrasives commonly used in industries are Borazon, Ceramic, Corundum, Dry Ice, Glass Powder, and Silicon Carbide.

While natural abrasives are often sold as dressed stones in the form of blocks, both naturally occurring as well as synthetic, abrasives are available in variety of shapes and sizes according to different use. These are usually bonded or coated abrasives, which includes blocks, belts, discs, wheels, sheets, rods, and loose grains. Grinding wheels are a type of abrasives that find a wide range of industrial applications, right from cutting, sharpening to shaping materials. Previously, such wheels used human power in the form of pedal or human operated cranks. However, now these comfortably work with the help of an electric motor. The high speed of motion imparted by such motors has necessitated the use of a coolant fuel for lowering of the resultant heat produced. However, many researchers suggest that such coolants or lubricants are more important to reduce the tensile stresses acting on the wheel.

The type of abrasive to be used for a particular work will be governed by the size, shape and the nature of the work piece, as well as the type of finishing desired.