|
An excellently divided, hard, refractory material ranging from 6 to 10 on the Mohs scale, used to reduce, smooth, clean or polish the surfaces of other less hard substances, such as glass, plastic, stone, wood etc. Natural abrasive materials include diamond dust, garnet, sand (silica), corundum (Al oxide, emery), pumice, rouge (Fe oxide), & feldspar; the more important synthetic types are Sic, B carbide, Ce oxide & fused alumina. Abrasives in powder form are used in several ways:(1) Applied directly to the surface to be treated by mechanical pressure or compressed-air blast, as in cleaning building stone (2) Affixed to a paper or textile backing after the particles have been coated with an adhesive (3) Mixed with a bonding agent such as Na silicate or clay, the particles being compressed into a wheel rotated by a power-driven shaft
Materials used in operations such as grinding, polishing, lapping, honing, pressure blasting or other similar process are also in the definition of abrasives. Abrasives come in different particle or grit sizes depending on how much material needs to be removed.
Abrasive materials are made of the materials generally characterised by high hardness and moderate to high crack stiffness.
Every firm abrasive particle acts like a single point cutting tool. With hundreds if not thousands available in a small area, the effect they produce is quite remarkable.
Abrasive are used where high volumes of material need to be removed, such as in rough polishing, large scratch removal or operations requiring significant shape or dimensional change. Better-quality grades are generally used after coarser grades to produce a higher surface finish than are possible with coarse grades.
Abrasives include some materials as silicon carbide, generally used for non-ferrous metals, aluminium oxide or alumina, the most widely used abrasive, generally used for ferrous alloys, high tensile materials and wood, Diamond, most often used in ceramic grinding or final polishing due to high hardness and cost, Cubic boron nitride (CBN), Garnet, usually used for machining of wood, Zirconia/Alumina alloys, suited to carbon and stainless steels and welds, Glass, usually used for pressure blasting operations, Colloidal silica, generally used for finishing operations as it is only available as a suspension of extremely fine particles.
Following are the types of abrasive materials
Bonded Abrasives
Coated Arasives
Non-Woven Nylon Abrasives
Metal Bonded Abrasives
Burs
Lapping Compound |
