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Polycrystalline diamond cutting tool (PCD) : PCD hardness is 8000 hv, 80 ~ 120 times of the carbide; Coefficient of thermal conductivity of 700 w/mK, 1.5 ~ 9 times for carbide, even higher than that of PCBN and copper, so the PCD cutting tool quickly heat transmission; Friction coefficient is generally 0.1 ~ 0.3 (carbide friction coefficient is 0.4 ~ 1), it can significantly reduce the cutting force; Thermal expansion coefficient of only 0.9 to 10 ^ 6-10 ^ 6-1.18 - and it was worth only 1/5 of the carbide, so the cutting tool thermal deformation is small, high machining accuracy; And its affinity with non-ferrous metals and non-metallic materials is very small, in the course of processing chip is not easy to form the devolop tumors on the blade