Towards the numerical simulation of tool wear induced residual stress drift

Finish turning is one of the key operations governing the residual stress of functional surfaces. The residual stress state is determined by the cutting conditions and the selected cutting tool system (macro geometry, cutting edge preparation, tool substrate, multi-layer coating…). However, this initial configuration evolves over time due to tool wear. Therefore, it seems fundamental to reproduce the wear process of the tool in order to understand the evolution of thermo-mechanical loadings applied to the machined surface. This work presents a numerical methodology for predicting the wear-induced residual stress drift in longitudinal turning. The complete 3D cutting tool is discretized into elementary 2D sections. A finite element based procedure is developed to calculate, considering each local tool geometry, the local loads withstood by the machined material. The latter are merged to generate equivalent 3D thermomechanical loadings implemented in a second macroscopic model able to calculate the residual stress state under different wear levels. Experimental cutting tests with artificially worn tools have confirmed that good agreement can be achieved.