Numerical analysis of the tribological and geometrical impacts of tool wear on the thermomechanical loadings induced by 15-5PH steel turning

Abstract

Finish turning is one of the key operations governing the residual stresses of functional surfaces. The residual stress state is determined by the thermomechanical loadings applied on the machined surface over time. These thermomechanical loadings depend on the cutting conditions and on the selected cutting tool system (macro geometry, cutting edge preparation, tool substrate, multi-layer coating…). However, this situation evolves over the time due to tool wear. At least two kinds of parameters are modified: the geometry of the tool (crater and flank wear) and the tribological phenomena between the cutting tool (wear of each layer of the coating) and the workmaterial. The thermomechanical loadings can be estimated thanks to a numerical model of the cutting operation. This work aims at investigating the sensitivity of tribological and geometrical parameters on the thermomechanical loadings withstood by the machined surface in an orthogonal cutting operation. Among the key criteria determining the residual stress state, this paper focuses on the analysis of the plastic deformation, the heat generation and the corresponding temperature near the machined surface. A finish turning of a 15-5PH steel with a carbide tool in dry conditions is considered. It is shown that tool geometry is dominantly affecting the thermomechanical loadings, whereas the sensitivity to friction is limited for this case study, despite a threshold effect for friction beyond 0.25.