With the advancement of science and technology, some high-performance tool materials have appeared one after another, which reflects the improvement and development of cutting technology.
The toughness and hardness of a single tool material of a coated tool generally cannot be taken into account. In recent years, a new process of coating on the surface of tool materials has been adopted, and good results have been achieved.
The coated tool is a 5~12um thick layer of refractory metal with high wear resistance on the high-speed steel or cemented carbide tool substrate with relatively good toughness, respectively, by physical vapor deposition or chemical vapor deposition. , such as titanium carbide (TiC), titanium nitride (TiN) and aluminum oxide (Al:O,) and so on. The cutting part of the tool not only has the strength and toughness of the base material, but also has high hardness and wear resistance of the coating material, which better solves the contradiction between strength, toughness, hardness and wear resistance, thereby improving the cutting tool. The comprehensive performance, especially suitable for high-speed cutting.
1) TiC coated inserts. Lathe TiC coating has high melting point, hardness and wear resistance, as well as good anti-oxidation ability. It can produce iron oxide film during cutting, which can reduce friction factor and reduce tool wear. Generally, the hardness can be higher than that of ordinary cemented carbide. More than 1 times, the cutting speed can be increased by about 40%. The bonding temperature of TiC and steel is high, the surface grains are fine, and it is not easy to produce built-up edge, which is suitable for fine turning.
2) TiN coated inserts. The TiN coating has a small affinity with iron-based materials and a low friction coefficient, which can effectively reduce the cutting temperature. The anti-oxidation ability and rear wear ability of the lathe are stronger than that of the TiC insert, the machined surface can be brushed to a smaller roughness value, and the tool life can be improved, and it is suitable for cutting plastic materials that are easy to stick to the tool.
3) Al: 0. Coated blades. Al:. , the coating has good thermal stability and high high temperature hardness at high temperature. When the lathe is cutting, the friction factor is small, and it is not easy to generate built-up edge, which can obtain a small surface roughness value and ensure the stability of dimensional accuracy.
4) Composite coating. At present, the single-coated inserts of lathes are rarely used, and composite coatings are mostly used, such as: TiC-TiN composite coating, TiC-AI203 composite coating.