Evolution of heat fluxes into Ti6Al4V machined surface due to tool wear

Abstract

The increase in temperature during machining, also known as the overheating phenomenon, remains a significant factor that influences the generation of part defects such as burr and hole size and determines the lifespan of critical aerospace components. During metal cutting, the heat distribution within the different shear zones may vary depending on the kinematic parameters of the process and the cutting-edge geometry. Tool wear changes the micro-geometry and leads to additional heat flux generation, particularly in the tertiary shear zone, exacerbating the situation. This article identifies the evolution of heat flux applied on the workpiece due to changes in cutting edge micro-geometry. An inverse method was developed to calibrate finite element simulation of Ti6Al4V cutting with orthogonal cutting tests instrumented with infrared thermal measurements. This method optimizes the intensity of heat fluxes, modeled as an external Gaussian-shaped source. The results indicate that the heat fluxes generated in the tertiary shear zone significantly increase with the evolution of the micro-geometry due to the ploughing effect and the flank wear friction. Their values reach up to 46 % of the initial flux generated by the primary shear zone for a worn tool.