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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. [ABSTRACT FROM AUTHOR]

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 very instructive to reproduce the wear process of the tool in order to understand the evolution of thermo-mechanical loadings applied to the machined surface. Flank wear is a parameter which can be difficult to fully control, and it is complex to reproduce experimentally. In this work, a simple, controlled and repeatable method of producing a known flank wear state is introduced and the impact of the flank wear on the surface integrity is assessed. This involves two parts, first reproducing a given flank wear state and second, evaluating experimentally the residual stress induced by the flank wear state on the workpiece. Carbide tools are used to turn 15-5PH steel under dry conditions. It is shown that the method produces consistent results. The effect of flank wear on residual stress is most notable and can generate data to validate numerical modelling. Areas for improving the method are also discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Finish turning is one of the key operations governing the residual stresses below the machined surface. The residual stress state depends on the cutting conditions and on the selected cutting tool system, i.e. macro geometry, cutting edge preparation as well as tool grade. However, tool wear often affects the interaction between the tool and the workpiece leading to severe modifications of the residual stress state. This work aims at investigating the influence of cutting tool wear on the surface integrity in longitudinal turning of a 15-5PH stainless steel. First, an experimental sensitivity study is performed to assess the effect of various wear modes on the residual stresses. Then a numerical model has been developed to understand the experimental observations and connect them to the thermomechanical loadings and local data within the near surface. The impact on residual stresses of three types of wear were tested (flank face wear, rake face wear and adhesion on the cutting edge) with the same cutting condition (V c =120m/min, a p = 0.2 mm and f = 0.2 mm.rev-1). Based on the experiment, the numerical simulation proposes to observe the impact of wear on thermomechanical loadings by simulated a tool with a rounded cutting edge, a crater on the rake face and high flank face contact length. It follows that the impact of the rake face wear is extremely low, contrary to the rounded edge or the flank face wear which increased the contact length and significantly impact the loadings. [ABSTRACT FROM AUTHOR]