Machined surface quality refers to the microscopic roughness of the machined surface of the part after machining, also known as roughness, represented by Ra, Rz, Ry three codes plus Numbers. Mechanical drawings will have corresponding surface quality requirements, generally the surface roughness of the workpiece, Ra<0.8um, is called: mirror. The surface quality directly affects the physical, chemical and mechanical properties of the processed workpiece. The working performance, reliability and life of the product depend on the surface quality of the main parts to a great extent. Generally speaking, important or key parts of the surface quality requirements are higher than ordinary parts. This is because the surface quality of good parts will greatly improve their wear resistance, corrosion resistance and fatigue damage resistance