3D finite element investigations of the influence of tool rake angle on cutting performance

Abstract

The aim of this project is to investigate the effect of tool rake angle on cutting performance. The 3D finite element model (FEM) of machining process was developed from the incipience state to the steady-state. The elastic-viscoplastic material properties, including the strain hardening, temperature softening and strain rate sensitivity, were used. The criterion for the chip formation was based on a critical accumulated inelastic strain. At the interface between tool/chip, the modified Coulomb’s law was implemented. An adiabatic condition was assumed to allow the heat generation from plastic deformation to transfer into heat. The FEM was validated using experimental results and good agreement was obtained. Cutting forces and passive force were found to decrease with the increase in rake angle for all cutting speeds investigated. On the other hand, the feed force was found to increase with the increase in rake angle. The maximum temperature increases with rake angle when the rake angle is smaller than 10°. There is a suitable rake angle for most of the cutting speeds where the temperatures are the smallest. For the cutting speed of100,200 and 250 m/min, the lowest temperature occurred at the rake angle of around 10°. Furthermore, the optimum rake angles, where the contact pressure is the lowest, is between 7° to 10° for the cutting speeds of 150,200 and 250 m/min. However, there is no optimum rake angle for the speed of 100 m/min. The contact lengths are stable for the rake angle of less than 10° for the cutting speeds of 150, 200 and 250 m/min. The contact lengths then increase as the rake angle are higher than 10°. However, for the low cutting speed of 100 m/min, the contact length increases with the decreasing rake angle. The results obtained from this study provide a fundamental understanding of the machining process mechanics and may assist in the optimisation of the coated tool design.