Amorphous diamond (also known as diamond-like carbon - Annotation) coating is a carbon film deposited by PVD process. It SP3 key part of the diamond, and SP2 key part of the carbon; film hardness is high, but lower than the hardness of diamond film; thickness thinner than we usually deposited diamond film. Machining graphite, amorphous diamond coated tool life is 2 to 3 times the uncoated carbide tools. Contrast, CVD diamond is a pure diamond coatings deposited by CVD process, the tool life when machining graphite is a cemented carbide tool 12 to 20 times, thereby reducing the number of tool changes, and improve the processing of the reliability and precision consistency
Can not use the diamond tool machining hardened steel

Diamond is constituted by carbon atoms. Certain materials when heated, will be sucked out from the diamond carbon atoms and the formation of carbides in the workpiece. Iron is one of these materials. The iron group material with a diamond tool machining, heat generated by friction will cause the diamond carbon atoms diffuse into the iron, cutting disc and the resulting diamond coating due to chemical wear and early failure.
Can not use the diamond tool machining hardened steel

Diamond is constituted by carbon atoms. Certain materials when heated, will be sucked out from the diamond carbon atoms and the formation of carbides in the workpiece. Iron is one of these materials. The iron group material with a diamond tool machining, heat generated by friction will cause the diamond carbon atoms diffuse into the iron, cutting wheel and the resulting diamond coating due to chemical wear and early failure.