(2) Coatings are the key technology to improve tool performance. Coating technology plays an important role in the development of modern cutting and cutting tools. The coating technology can achieve very good comprehensive mechanical properties of the cutting tool, not only effectively improve the service life of the tool, but also greatly improve the cutting efficiency of the Chinese metal processing online , so the coated tool becomes a high-speed cutting technology. The fastest-growing tool has a ratio of more than 50% in the tool. The coating tool is mainly used in drills, reamers, taps, hobs, inserts and carbide inserts.
Chemical coating (CVD) is the main coating process for indexable inserts. By chemical vapor deposition and vacuum sputtering, a layer of TiC or Al2O3 with a thickness of 5 ~ 12μm is sprayed on the surface of the cemented carbide tool. Improve the hardness of the tool surface and improve wear resistance and lubricity.
Among them, the hardness of Al2O3 coated tool is up to 300HV, which has higher high temperature hardness and stability. The two-layer and three-layer composite coatings such as TiC-TiN and TiC-TiN-Al2O3 have better cutting performance. CVD diamond coatings have also made progress, reducing the surface roughness of coatings, and entering the practical stage of China Metalworking Online . At present, the coating ratio of foreign carbide indexable inserts has reached more than 70%.
The progress of physical coating (PVD) has attracted remarkable progress, and significant progress has been made in furnace structure, process, automatic control, etc., and not only heat-resistant coatings suitable for high-speed cutting, dry cutting, and hard cutting have been developed. , such as Super TiAlN, and TiAlCN, which has better comprehensive performance, all rights reserved coatings and DLC, W/C anti-friction coatings, and through the innovation of coating structure, nano-scale ultra-thin super multi-layer coating The development and application of new coating materials will be accelerated, and the hardness and toughness of the coating will be greatly improved. The coating will become the main way to improve the performance of the tool.
(3) The use of superhard tool materials ceramics, PCBN and diamond will significantly increase ceramic knives with alumina-based Al2O3 and silicon nitride-based Si3N4, with high hardness and wear resistance, heat resistance up to 1200 °C Above, the chemical stability is good, the affinity with metal is small, the cutting speed can be increased by 3 to 5 times, and the high hardness material of 65HRC can be processed.
However, ceramics have poor impact toughness, so the requirements for high-speed cutting are high, that is, the material to be processed is required to be uniform, and the direction, angle and speed of the tool approaching the workpiece are very strict. Ceramic and cermet tool materials replace hard alloys in the finishing and semi-finishing of steel and cast iron, improving processing efficiency and product quality.
Polycrystalline cubic boron nitride (PCBN) is a soft hexagonal boron nitride added under high temperature and high pressure. It has better chemical stability than diamond, hardness up to 8000 ~ 9000 HV, good wear resistance and heat resistance up to 1400. °C, which is chemically inert with iron, is suitable for processing materials with high hardness, and will become the main tool material for high-speed cutting of ferrous metals, difficult-to-machine materials, and dry cutting and hard cutting.
Most of the diamond used to produce cutting is synthetic diamond. There are three types of synthetic diamonds: polycrystalline diamond (PCD), chemical vapor deposited diamond (CVD), and high temperature synthetic single crystal diamond. PCD and single crystal diamond are the best tools for the efficient and precise processing of non-metallic materials such as non-ferrous metals, ceramics, glass and graphite.
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