Turned parts are a kind of parts processed by a lathe on a lathe. The rotary motion of the workpiece and the linear or curved motion of the tool are used to change the shape and size of the blank, and it is processed to meet the requirements of the drawing. Turning is a method of cutting a workpiece on a lathe by rotating the workpiece relative to the tool. The cutting energy provided by turning is mainly provided by the workpiece rather than the tool. Turning is the most basic and common cutting method, which occupies a very important position in production. Turning is suitable for turning surfaces. Most of the workpieces with turning surfaces can be processed by turning methods, such as inner and outer cylindrical surfaces, inner and outer conical surfaces, end faces, grooves, threads and rotary forming surfaces. Turning accuracy is generally IT11-IT7, some can reach IT6, and the surface roughness Ra can reach 12.5-08um. Turned parts are called turned parts, and there are many types of turned parts. It is famous for hard turning to maintain the thermal stability of parts.