With the increase of the number of high-precision and high hardness mechanical parts, as well as the development of precision casting and precision forging technology, the performance, variety and output of grinding machines are constantly improving and growing. (1) Cylindrical grinder: It is a basic series of ordinary type, mainly used for grinding cylindrical and conical external surfaces. (2) Internal grinder: It is a common base type series, mainly used for grinding cylindrical and conical internal surfaces. In addition, there are grinding machines with both internal and external circular grinding. (3) Coordinate grinder: internal grinder with precise coordinate positioning device. (4) Centerless grinder: The workpiece is clamped centerless, generally supported between the guide wheel and the bracket, and the guide wheel drives the workpiece to rotate. It is mainly used for grinding cylindrical surfaces. For example, bearing shaft support. (5) Surface grinder: mainly used for grinding the surface of workpiece. a. The hand grinder is suitable for processing small size and high precision workpieces, and can process various special-shaped workpieces including camber, plane, groove, etc. b. The large water mill is suitable for processing larger workpieces, with low processing accuracy, which is different from the hand grinder. (6) Abrasive belt grinder: A grinder that uses fast moving abrasive belts for grinding. (7) Honing machine: It is mainly used to process various cylindrical holes (including smooth holes, axial or radial discontinuous surface holes, through holes, blind holes and multi step holes), as well as conical holes, elliptical holes and cycloidal holes. (8) Grinder: It is used to grind the inner and outer surfaces of the workpiece plane or cylinder. (9) Guide rail grinder: mainly used for grinding the guide rail surface of the machine tool. (10) Tool grinder: A grinder used for grinding tools. (11) Multi purpose grinding machine: It is used for grinding cylindrical and conical inner and outer surfaces or planes, and can use servo devices and accessories to grind a variety of workpieces. (12) Special grinding machine: a special machine tool used for grinding certain types of parts. According to its processing objects, it can be divided into spline shaft grinder, crankshaft grinder, cam grinder, gear grinder, thread grinder, curve grinder, etc. (13) Face grinder: a grinder used for grinding the end face of gears.