Cubic boron nitride is the second hardest material in the world invented successfully in 1957; the hardness of CBN’s single crystal is HV8000-9000 while the hardness of PCBN is HV 2500—5000, so its considerably better abrasive resistance than tungsten carbide and ceramics. With a higher ability of oxidation resistance within 1000℃, CBN will not have any chemical reaction together with ferrous material in 1200–1300℃. So it is unique for CBN material dry cutting ferrous materials. The principal application areas for CBN cutting tools are hardened steels, cast irons and sintered irons as well as powder metallurgy components.