Wear Mechanism Analysis and Its Effects on the Cutting Performance of PCBN Inserts during Turning of Hardened 42CrMo

Abstract

Super-strength steel 42CrMo after quenched and tempered has been widely applied to crucial parts due to the properties such as good impact toughness and high fatigue limit. However, it falls into the category of most difficult-to-cut material because of its high cutting resistance and low thermal conductivity, which can easily lead to tool breakage. To increase efficiency, ensure quality and reduce costs, wear modes and its corresponding mechanism of PCBN inserts were experimentally investigated during turning of the hardened 42CrMo (62-65 HRC) in this paper. The results suggest brittle fracture is the main failure mode. The wear mechanism was mainly abrasive wear and adhesion/diffusion wear, accompanying oxidation wear and chipping. Within the cutting range studied in this work, the operation for turning instead of grinding can be realized and the optimal cutting speed range is 140–170 m/min. The static forces fluctuate with tool wear, while other performance indexes such as maximum cutting forces, impact forces, cutting power, specific cutting energy, and coefficient of friction at the tool-chip interface all show a rising trend with tool wear, which can be extracted as features. The research results obtained in this paper will provide guidelines for the industrial production and tool wear real-time monitoring.