Cutting performance, tool performance has a decisive influence on cutting efficiency, accuracy and surface quality. There is always a contradiction between the two key indicators of tool performance - hardness strength (toughness). High hardness materials tend to have low strength and toughness, and toughness is often at the expense of hardness. The soft tool base is coated with one or more layers of high-strength, wear-resistant metal or non-metallic compound film (such as TiC, TiN, Al2O3, etc.) to form a coating tool, which better solves the contradiction between tool strength and toughness. The cutting tool developed a revolution. Coated tools have been the fastest growing new tool in the last 20 years. At present, coated tools in industrialized countries have accounted for more than 80%, and more than 90% of cutting tools used on CNC machines have coated tools. 1 coating tool, coating material and coating method 1) Coating tool features The coated tool combines the high hardness and high toughness of the substrate with high hardness and high wear resistance, which improves the wear resistance of the tool without reducing its toughness. The coating tool has a wide versatility and a wide range of processing, and the use of coated tools can achieve significant economic benefits. A coated tool can be used in place of several non-coated tools, which greatly reduces tool inventory, simplifies tool management, and reduces tooling costs. However, after the coating process of the existing coating process, the material properties of the coating material of the base material are different, the internal stress of the coating residue is large, the interface bonding strength between the coating substrates is low, the coating is easy to peel off, and the coating process is still The disadvantages are that the strength of the substrate is lowered, the resharpability of the coating blade is poor, the coating equipment is complicated, expensive, the process requirements are high, the coating time is long, and the tool cost is increased. 2) Common coating materials and properties Common coating materials Common coating materials include carbide, nitride, carbonitride, oxide, boride, silicide, diamond and composite coatings in dozens of categories. These coating materials can be classified into metal bond type and covalent bond type ion bond type according to the chemical bond characteristics. Coating material properties Metal bond coating materials (such as TiB2, TiC, TiN, VC, WC, etc.) have high melting point, low brittleness, high interface bonding strength, strong interaction tendency, good multi-layer matching, good comprehensive performance, and most common coatings. material. The covalent bond type coating materials (such as B4C, SiC, BN, diamond, etc.) have high hardness, low coefficient of thermal expansion, poor bonding strength with the interface of the substrate, and poor stability of multilayer adhesion. The ion-bonded material has good chemical stability, large brittleness, large thermal expansion coefficient, low melting point and low hardness. These coating materials use up to TiC, TiN, Al2O3, diamond and composite coatings. TiC has good wear resistance and can effectively improve the anti-crater wear resistance of the tool. It is suitable for low speed cutting and wear. TiN coating has low friction coefficient, good lubrication performance, can reduce cutting hot cutting force, and is suitable for generating fusion wear. Cutting; Al2O3 high temperature wear resistance, heat resistance and oxidation resistance better than TiCTiN, low crater wear rate, suitable for high speed, large cutting hot cutting; diamond coating hardness, high thermal conductivity, low friction coefficient, suitable for colored Metal alloys are cut at high speed; while composite coatings combine several coating materials, they are currently dominated by a two-coat, three-coat combination. Currently, coating methods such as CVD (Chemical Vapor Deposition) PVD (Physical Vapor Deposition) are commonly used, and other methods such as plasma spraying, flame spraying, electroplating, and dissolved salt electrolysis have significant application limitations. The CVD method utilizes metal halide vapors, other chemical components of hydrogen, and a gas-solid reaction such as decomposition, heat-sealing, or chemical transfer to heat the surface of the substrate to form a solid deposited layer at a high temperature of 950 to 1050 °C. The CVD process has high requirements, and the chlorine corrosion and hydrogen embrittlement deformation may cause the coating to be easily broken and the strength of the substrate section to decrease. When the cemented carbide is coated, the decarburization phenomenon is easily formed to form the n phase. In recent years, the low temperature CVD PCVD method has been successfully developed to improve the original CVD process. Next page Exit Sign ,Exit Sign With Lights,Photoluminescent Exit Signs ,Emergency Exit Door Sign Effort Semiconductor Lighting Ltd. , https://www.effortem.com
3) Common coating methods