The tool coating treatment is one important way to improve tool performance. Appears coated tools, the tool cutting has been a major breakthrough. The tool is coated on the cutter body toughness, and good wear resistance coating layer or layers of refractory compounds, it is the tool substrate and a hard coating layer combination, which greatly improves the performance of the tool. Coated tools can improve processing efficiency, improve accuracy and extend tool life, reduce processing costs.      The new CNC machine tools used in cutting tools have about 80% of the use of coated tools. Coated tools will be the future of the most important areas of CNC machining tool varieties.      ⑴ types of coated tools      Depending on the method of coating, coated tools can be divided into chemical vapor deposition (CVD) and physical vapor deposition coated tools (PVD) coated tools. Coated carbide tools commonly used chemical vapor deposition, the deposition temperature of about 1000 ℃. Coated high-speed steel cutting tools commonly used physical vapor deposition, the deposition temperature of about 500 ℃;      Depending on the substrate material coated tools, carbide coated tools can be divided into coated tools, high speed steel coated tools, as well as ceramics and superhard materials (diamond and cubic boron nitride) coating on the tool.      Depending on the nature of the coating material, coated tools can be divided into two categories, namely, "hard" coated tools and 'soft' coated tools. "Hard" The main objective of coated tools in pursuit of high hardness and wear resistance , and its main advantage is the high hardness, wear resistance, typically TiC and TiN coatings. "soft" coated tools goal is a low friction coefficient, also known as self-lubricating tool, it is friction with the workpiece material coefficient is very low, only about 0.1, can reduce adhesion, reduce friction, reduce cutting forces and temperatures.      Recently developed a nano-coating (Nanoeoating) tool. Such coated tools can be a variety of different combinations of coating materials (such as metal / metal, metal / ceramic, ceramic / ceramic, etc.), in order to meet different functional and performance requirements. Rational design of nano-coating allows the tool material has excellent tribological function and self-lubricating properties, suitable for high-speed dry cutting.