The CVD diamond film coating is a new style material. It is superior to cemented carbide on cutting performances. The CVD diamond films coated tools are used for machining non-ferrous metals and nonmetals. Through cutting tests of machining graphite, the experiments were designed to study tool life of the diamond film coated compared with cemented carbide. Results imply that the diamond film coated tool enjoys many advantages over uncoated one, such as high hardness, high wear resistance, low friction coeff...