Amorphous diamond (also known as diamond-like carbon) coating is a carbon film deposited using a PVD process. It has a part of the diamond SP3 bond, but also has a part of the carbon SP2 bond; the film hardness is high, but lower than the hardness of diamond film; its thickness than we usually deposited diamond film to be thinner. When graphite is processed, the life of amorphous diamond coated tools is 2-3 times that of uncoated carbide tools. CVD diamond, on the other hand, is a pure diamond coating deposited using a CVD process, with 12-20 times the tool life of graphite when machining graphite, which reduces tool change times and increases machining reliability and accuracy consistency.