Finite element investigation of cutting performance of Cr/W-DLC/DLC composite coated cutting tool

Abstract

Coupled with a thermo-mechanical metal cutting process, rapid tool wear, higher surface roughness and mass heat are caused by the rapid plastic deformation of the workpiece and by the friction along the tool-chip interface. This phenomenon is more predominant in the machining of difficult-to-cut materials. DLC film has been applied as coating material in the machining of difficult-to-cut materials, and shows a good cutting performance. In this study, Cr/W-DLC/DLC coated tools were compared with other three coated tools (i.e., TiC-, TiAlN-, Al 2 O 3 -) to investigate the cutting performance in the machining of Al-Si alloy (AC9B). In addition, the influence of Cr/W-DLC/DLC coated tools on the cutting performance under different cutting speeds was studied. Cutting force, cutting temperature, heat transfer coefficient of the rake face of the tool, cutting deformation rate, plastic deformation of machined surface, the interface temperature and stress were investigated numerically based on Finite Element Method (FEM). Actual cutting experiments were carried out to the verification of the FEM models by means of the cutting force and cutting temperature measurement. The investigation results showed that Cr/W-DLC/DLC coated tools has the lowest cutting force and cutting temperature, good cutting deformation characteristics and lower coating-substrate interface temperature and stress, however appears the maximum value of heat partition coefficient into the cutting tool. With the increasing of cutting speeds, cutting force and cutting temperature showed an increase trend, while the plastic deformation depth of machined surface and heat partition into cutting tool all showed a decrease trend. This investigation can provide the theory basis or technical guidance for the cutting practice of Cr/W-DLC/DLC coated tools.