Lapping is one of the finishing processing methods of gears. The processing principle is to make the lapping gear and the lightly braked lapping wheel mesh freely with no gap, and add abrasive between the meshing tooth surfaces to make use of the relative sliding of the tooth surfaces. , to cut a very thin layer of metal from the tooth surface of the gear to be ground to achieve the purpose of reducing the surface roughness value and correcting the error of the gear part.

The precision of tooth lapping mainly depends on the precision of the gear before lapping and the precision of the lapping wheel, and lapping can only effectively improve the quality of the tooth surface and slightly correct the error of tooth shape and tooth orientation, but it has little improvement on other precisions.