Lapping is a precision machining method that uses free abrasive grains and a lapping plate to finish workpieces with high precision and to a super-mirror surface. Because the processing pressure is low, it suppresses the formation of altered layers and burrs, achieving micron-order precision in dimensional accuracy, flatness, and parallelism. A typical processing method is wet lapping, where a lapping fluid with abrasive grains such as diamond or GC (silicon carbide) dispersed is supplied while the workpieces are moved relative to the lapping plate. It is widely used for the final finishing of hard-brittle and difficult-to-machine materials such as semiconductor wafers, optical lenses, precision machine parts, ceramics, and cemented carbides, contributing to improved sliding properties and airtightness.