⑴ Types of coated tools

According to different coating methods, coated tools can be divided into chemical vapor deposition (CVD) coated tools and physical vapor deposition (PVD) coated tools. Coated carbide cutting tools generally use chemical vapor deposition method, and the deposition temperature is around 1000°C. Coated high-speed steel cutting tools generally use physical vapor deposition method, and the deposition temperature is around 500°C;

According to the different substrate materials of coated tools, coated tools can be divided into carbide coated tools, high-speed steel coated tools, and coated tools on ceramics and superhard materials (diamond and cubic boron nitride).

According to the properties of the coating material, coated tools can be divided into two categories, namely "hard" coated tools and 'soft' coated tools. The main goals pursued by "hard" coated tools are high hardness and wear resistance Its main advantages are high hardness and good wear resistance, typically TiC and TiN coatings. The goal pursued by "soft" coating tools is a low friction coefficient, also known as self-lubricating tools, which friction with the workpiece material The coefficient is very low, only about 0.1, which can reduce adhesion, reduce friction, and reduce cutting force and cutting temperature.

Recently, nanocoating (Nanoeoating) cutting tools have been developed. Such coated tools can use different combinations of coating materials (such as metal/metal, metal/ceramic, ceramic/ceramic, etc.) to meet different functional and performance requirements. Properly designed nano-coatings can make tool materials have excellent friction-reducing and anti-wear functions and self-lubricating properties, making them suitable for high-speed dry cutting.

⑵ Characteristics of coated cutting tools

The performance characteristics of coated cutting tools are as follows:

① Good mechanical and cutting performance: Coated tools combine the excellent properties of the base material and the coating material. They not only maintain the good toughness and high strength of the base material, but also have the high hardness, high wear resistance and low Friction coefficient. Therefore, the cutting speed of coated tools can be increased by more than 2 times than that of uncoated tools, and higher feed rates are allowed. The life of coated tools is also improved.

② Strong versatility: Coated tools have wide versatility and significantly expand the processing range. One coated tool can replace several non-coated tools.

③ Coating thickness: As the coating thickness increases, the tool life will also increase, but when the coating thickness reaches saturation, the tool life will no longer increase significantly. When the coating is too thick, it will easily cause peeling; when the coating is too thin, the wear resistance will be poor.

④ Regrindability: Coated blades have poor regrindability, complex coating equipment, high process requirements, and long coating time.

⑤ Coating material: Tools with different coating materials have different cutting performance. For example: when cutting at low speed, TiC coating has advantages; when cutting at high speed, TiN is more suitable.

⑶Application of coated cutting tools

Coated tools have great potential in the field of CNC machining and will be the most important tool variety in the field of CNC machining in the future. Coating technology has been applied to end mills, reamers, drill bits, composite hole processing tools, gear hobs, gear shaper cutters, gear shaving cutters, forming broaches and various machine-clamped indexable inserts to meet various requirements of high-speed cutting processing. The needs of materials such as steel and cast iron, heat-resistant alloys and non-ferrous metals.