Tool Wear, Cutting Forces and Temperature Evaluation When Turning Hardened Bearing Steel Using PCBN and Ceramic Tool Materials

Abstract

The paper details the machining of fully hardened MSI E52100 bearing steel (62 HRC) using commercial high and low concentration polycrystalline cubic boron nitride (PCBN) and conventional mixed ceramic tooling. Continuous turning tests were conducted under both roughing and finishing conditions and a full factorial experimental design was used to evaluate tool material performance. Under rough cutting conditions the PCBN tools presented higher wear resistance, whereas when finishing, the mixed alumina and low concentration PCBN provided consistently good results both with regard to tool life and workpiece surface finish. Sample SEM micrographs of worn tools are presented which suggest that diffusion and abrasive wear were the principal causes of tool failure. No evidence of built-up edge or notching (leading or trailing edge) was observed over the operating range. Three component cutting force measurement showed forces when roughing to be 6-9 times higher than when fmishing. Finally, a series of temperature measurement experiments are detailed using a remote implanted thermocouple.