CNC milling is an indispensable process in modern machining. The process different from turning is that turning is the high-speed rotation of the machined part, and the tool moves slowly along the x.y.z direction on the tool holder to cut off the material. CNC milling process adopts that the material does not move, the tool rotates at high speed on the tool holder and moves slowly along the three directions of x.y.z to cut off the material. At the same time, NC milling machine tools are generally equipped with tool magazine, which can automatically select the tool through the program to realize the whole process of unmanned operation, stabilize the quality, improve the efficiency, and reduce the labor cost and man-made impact on the quality.