Abrasive

Abrasive refers to a material containing hard particles used to wear away surfaces by friction. Abrasives are selected for hardness, friability, and cutting ability, and are used to shape metal, stone, wood, glass, and ceramics. They can be natural minerals or synthetic compounds, and are formed into tools and articles for grinding, polishing, or finishing. Effectiveness depends on particle size, shape, and bonding.

Natural abrasives include emery and garnet, historically common for grinding and polishing. Most modern abrasives are synthetic, such as aluminum oxide (corundum), silicon carbide, boron carbide, and synthetic diamond or cubic boron nitride (CBN). Different types vary in hardness and fracture behavior; for example, silicon carbide is useful for stone and nonferrous metals, while diamond and CBN offer extreme hardness for hard materials.

Abrasives are used in bonded forms, where grains are held in a rigid matrix to produce wheels, blocks, or stones, and in coated forms, where grains are bonded to a flexible backing in sheets or belts (sandpaper and discs). They operate by grinding, cutting, or lapping, and require appropriate grit size, backing, and bond to control material removal, heat, and surface finish. Friability of grains influences edge sharpness as they fracture.

Coarser grits remove material quickly but roughen surfaces; finer grits yield smoother finishes. Selection depends on material hardness, desired finish, and production needs. Finishing often uses progressively finer grits to minimize roughness.

Hazards include inhalation of dust containing crystalline silica and other particles; proper ventilation, dust control, and personal protective equipment are essential. Industry standards govern exposure limits and equipment safety.