(1) It can improve the machining flexibility, break through the limitation of the grinding wheel. And produce workpiece with different geometric shapes by changing the cutting edge and the way of walking the cutting tool;(2) The environmental protection problem in cutting processing is increasingly serious, the waste fluid and waste generated by grinding processing are more and more difficult to deal with and remove. And harmful to the human body, and the hard cutting without adding coolant, significant; (3) High cutting efficiency, short processing time, small equipment investment, can reduce the processing cost; (4) The energy consumed by cutting the same volume is only 20% of the grinding, so the cutting heat generated is less. And the processed surface is not easy to cause burns and micro-cracks, which is easy to maintain the integrity of the workpiece surface performance; (5) Under the same metal removal rate, hard cutting saves energy compared with grinding. Tools commonly used for hard cutting are ceramic, TiC coated blades and PCBN tool materials, but PCBN is the best tool material for hard turning at a high speed (above 1000m/min). For example, in the automobile gearbox synchronizer set fork (material is 20CrMnTi, hardness is HRC58 ~ 62) processing with the car grinding, the efficiency increased more than 4 times, the processing cost reduced to the original grinding process 1/3 ~ 1/2.