Lapping is a precision machining process used to produce flat surfaces on a variety of materials. It involves the use of a loose abrasive material, typically diamond or silicon carbide, suspended in a liquid or paste. The workpiece is held against a rotating lap, a flat surface made of cast iron, copper, or other materials, while the abrasive slurry is applied. The lap rotates at a slow speed, typically between 50 and 200 rpm, and the workpiece is moved back and forth across the surface of the lap. The process is repeated with progressively finer abrasives until the desired surface finish is achieved. Lapping is commonly used in the production of optical components, semiconductor wafers, and precision bearings.