abrasiv

An abrasive is a material used to wear away, cut, grind, or polish another surface by friction. Abrasives exist as loose grains, powders, or as components of engineered tools such as grinding wheels and sanding belts. They are categorized as bonded abrasives, where abrasive grains are held in a matrix, and coated abrasives, where grains are affixed to a backing material by a layer or coating.

Common abrasive materials include natural minerals such as emery and garnet, and synthetic grains such as alumina (aluminum oxide), silicon carbide, cubic boron nitride, and diamond. The choice depends on hardness, toughness, and friability of the grain, as well as the workpiece material and desired finish.

Grit size describes particle size; standards such as FEPA or ANSI provide ranges. Generally, coarser grits produce faster material removal but rougher finishes; finer grits produce smoother finishes. Bond types may be vitrified or resin-based, metal, or rubber, affecting tool rigidity and heat dissipation.

Typical applications include grinding metal to shape and size, deburring, surface finishing, sanding wood, and polishing stone or glass. In addition to wheels and belts, loose abrasives are used in blasting or lapping processes.

Safety: dust can be hazardous; respirable crystalline silica is a concern with some materials. Proper ventilation, guards, hearing protection, eye protection, and dust controls are important. Wheel selection and dressing, machine speed, and cooling are important to prevent wheel fracture and overheating.

History: The concept extends back to ancient emery and natural abrasives; synthetic abrasives developed in the 20th century expanded capabilities.