Selection of CBN Cutting Tools
a) CBN’s hardness and wear-resistance only second to diamond ,meanwhile it has very good high-temperature hardness .Comparing to Cermets ,its heat-resistance and chemical stability are not so good as the cermets ,but better at toughness and anti-damage performance.It has been widely used in cutting machine of hardened steel(HRC≥50),pearlitic gray cast iron,chilled cast iron and high-temperature alloys.Compared with tungsten carbide tools ,its cutting speed is capable to be increased by an order of magnitude.
b) The CBN cutting tools with high content of PCBN has high hardness ,wear-resistance,anti-press strength and anti-shock toughness,but also with disadvantage at bad heat stability and low chemically inert and is suitable for cutting machining of heat-resistance alloys,cast iron and iron-series sintered metals .On the contrary ,the PCBN cutting tools with low content of CBN powder,which take cermets as binder ,its hardness is low but compensate to previous material’s bad heat stability and low chemically inert ,and suitable to machining hardened steel
.
c) When cutting machine gray cast iron and hardened steel,we can select cermets cutting tools or CBN
ones ,so ,we have to take cost and machining quality analysis ,so as to decide select which one .The PCBN cutting tools performance better than on Al2O3 and Si3N4 when machine gray cast iron .However when dry machine hardened steel,the Al2O3 cutting tools cost is much cheaper than PCBN ones .Actually the cermets cutting tools have very good heat-resistance and chemically stability ,but not so good as PCBN in toughness and hardness.Consequently ,when take cutting machining on the material under HRC60 with small feed ,the cermets tools are a good choice ,the PCBN cutting tools is suitable to machine the material with hardness above HRC60,especially it is more suitable in automatically and high-precision machining .In addition to that ,in the same wear of flank face of the cutting tools ,the residual stress on the surface of the workpiece is much stable after machined by the PCBN cutting tools
