Turning of hardened 100Cr6 bearing steel with ceramic and PCBN cutting tools

This work deals with the machinability of hardened 100Cr6 bearing steel (62–64 HRC) when continuous dry turning using mixed alumina, whisker reinforced alumina and polycrystalline cubic boron nitride (PCBN) inserts. A full factorial experimental design was employed and the cutting range tested was as follows: cutting speed varying from 70 to 210 m/min and feed rate from 0.08 to 0.28 mm/rev. Tool life and surface finish were evaluated. As far as tool life is concerned, best results were obtained with the PCBN compact, followed by the mixed alumina tool at low feed rates and by the whisker reinforced alumina when feed rate was increased. Comparable surface roughness values were produced, with Ra values as low as 0.25 μm.