Investigations on Mechanisms of Tool Wear in Machining of Ti-6Al-4V Using FEM Simulation

Abstract

The titanium alloy Ti-6Al-4V is used very often for highly stressed components like compressor wheels because of its excellent mechanical and thermal properties. However, when machining components made of Ti-6Al-4V, their high tensile strength in combination with a low Young's modulus and a low thermal conductivity leads to high thermal and mechanical stresses in the cutting tools, which in turn lead to a particularly fast tool wear. Thus, optimization of the manufacturing process is required. However, to obtain this goal the mechanisms of tool wear were studied numerically and some results are presented in this article. Ti-6Al-4V forms segmented chips for the whole range of cutting velocities. The mechanical and thermal load variations due to the segmentation are taken into consideration during these investigations. A FEM model using a self-developed continuous remeshing method to form segmented chips was developed. Thus resulting state variables like stresses, temperatures and relative velocities between the tool face and the chip along the cutting tool can be investigated, which are well known for influencing tool wear in machining. The distributions of these state variables along the cutting tool, especially in the area of the cutting edge, are analyzed and related to experimentally caused tool wear. In order to evaluate the developed simulation model, orthogonal cutting experiments have been conducted with uncoated carbide (WC/Co) cutting tools. Simulated results are compared with experimentally obtained data for different process parameters.