1.Select mold NC milling cutter in mold NC machining, milling parts inside and outside contour and milling plane commonly used flat end milling cutter, for some three-dimensional surface and variable angle contour shape processing, commonly used spherical milling cutter, ring milling cutter, drum milling cutter, conical milling cutter and disc milling cutter.   Mould milling cutter is used to process the forming surface of mould cavity, and the machining of cavity mainly depends on various end milling cutters. Mould milling cutter is evolved from end milling cutter. According to the shape of the working part, it can be divided into conical flat head, cylindrical ball head and conical ball head. According to the material is divided into carbide mold milling cutter, high speed steel mold milling cutter, etc. Cemented carbide die milling cutter is widely used, in addition to milling various mold cavity, can also replace the hand file and grinding wheel grinding head for cleaning casting, forging, welding workpiece flash, and some forming surface finishing.   2. The reasonable tool life of die and mould milling cutter is generally divided into the maximum productivity tool life and the minimum cost tool life. The former is determined according to the minimum working hours of a single piece, and the latter is determined according to the minimum process cost.   Compared with the ordinary machine tool processing method, CNC machining puts forward higher requirements for the tool, which not only requires good rigidity and high precision, but also requires stable size, high tool life, and convenient installation and adjustment to meet the requirements of high efficiency of CNC machine tools. The cutters selected on CNC machine tools are often made of cutter materials that are suitable for high-speed cutting, and the transferable blades are used. Standard for Tool Life of Multi - tool Machine Tools and Combined Machine Tools with Complicated Tooling, Tool Changing and Tool Adjusting