Coated tool
Coated tools are growing rapidly, and more than 80% are currently coated tools. Widely used in the coating of different nitrides, oxides and borides on cemented carbide and high speed steel knives, among which alumina (Al2O3), titanium carbonitride (TiCN), titanium aluminum nitride (TiAlN) , titanium aluminum carbonitride (TiAlCN), etc., have excellent high temperature performance. From single coating to multi-coating, the coating process includes chemical vapor deposition (CVD) and physical vapor deposition (PVD). The PVD method is mainly used for high speed steel tools, and both CVD and PVD methods can be used for cemented carbide tool coatings. The PVD method of cemented carbide knives has good resistance to breakage and is suitable for interrupted cutting, but the wear resistance is not as good as that of CVD. The coating tool has different properties depending on the coating material. The coated carbide tool has high hardness and wear resistance (2100～4200HV), high heat resistance (1000～1200°C), high resistance. Excellent bonding properties, high chemical stability and low coefficient of friction, etc., excellent WC-based, TiC (N)-based cemented carbide and ceramics can be used as the substrate of the coating tool. At present, coating materials for coated carbide tools suitable for high-speed cutting mainly include CVD TiCN+Al2O3+TiN, TiCN+Al2O3, TiCN+Al2O3+HfN, TiN+Al2O3 and TiCN, and PVD composite coating TiAlN/TiN. , TiAlN, etc. Single-coated TiC or TiN is no longer needed. Coated carbide tools with different coating materials can be used to process steel, alloy steel, stainless steel, cast iron and alloy cast iron at speeds of 200 to 500 m/min. Carbon nitride (CNx), nitride (TiN/NbN, TiN/VN) developed in recent years have good thermal stability at high temperatures and are suitable for high-speed cutting. Soft-coated tools (such as MoS2, WS2 coated high-speed steel tools) are mainly used to process high-strength aluminum alloys, titanium alloys or precious metals. The nano TiN/AlN composite coated milling insert recently developed in Japan has a coating of 2000 layers and a thickness of 2.5 nm per layer, which can be cut at high speed. At present, complex tools (bits, gear tools, broaches, etc.) are mainly coated with hard coatings such as TiCN and TiN on high-performance high-speed steel substrates. Coated tools are not suitable for rough machining and large impact interrupted cutting under special heavy loads and high hardness materials (such as hardened steel and chilled cast iron). When the coated tool is cut at low speed, it is prone to peeling and chipping, etc. After the coated tool is reground, the coating effect is reduced.
Powder metallurgy high speed steel (PM HSS)
In recent years, industrial developed countries have vigorously developed powder metallurgy high-speed steel, which is a small high-speed steel powder directly obtained from high-pressure steel molten steel atomized by high-pressure argon or pure nitrogen, and then hot isostatically pressed under high temperature and high pressure. Steel ingots, which are then made into high-speed steel. Compared with the high-speed steel manufactured by the fusion method, it has the advantages of no carbide segregation, fine and uniform grain powder, up to 2~3μm, hardness after heat treatment of 67-70HRC, and bending strength 0.5~1 times. The high temperature hardness at 600 ° C is 2 to 3 HRC higher, and the tool life is increased by 0.5 to 2 times under the same cutting conditions. Due to the isotropy of physical and mechanical properties, heat treatment deformation and stress can be reduced, making it suitable for manufacturing complex tools such as drills, broaches and gear tools. The cutting speed of this type of high-speed steel tool can be multiplied. After the surface PVD coating TiN, TiCN, TiAlN, the cutting speed can reach 150-200m/min. In the field of high-speed cutting of complex tools, powder metallurgy high-speed steel coated tools will further develop and occupy an important position.
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