Numerical simulation of the influence of tool geometry on energy consumption during micro turning of titanium alloy

Abstract

Fabrication of an axisymmetric biomedical implant with good dimensions, form and surface integrity features are a challenging task in the micro-manufacturing industry. This is due to workpiece deflection, vibrations, tool wear and adhesion of the chip on the cutting inset during the micromachining process. So experimental evaluation on the variation of tool geometry is expensive and difficult as stated in prior literature. So, in this work, a finite-element method simulation is developed to comprehend the physics of the process and predict the energy consumption by incorporating the effect of material strengthening caused by shearing of material across the grain, shear band pattern upon strain rate and tool geometry such as edge radius, nose radius and rake angle. The modified Johnson-Cook material model is used to state the flow stress and an adaptive remeshing technique is utilized to model the plastic deformation at a higher strain rate during the simulation process. Initially, the model is developed in a transient state and then modified to a steady-state to obtain the output process parameters. The proposed model is calibrated and validated with experimental results reported in the literature. It is inferred that the cutting force, thrust force and feed force acquired from finite-element method simulation have been confirmed experimentally with prediction accuracy of 94%, 82.66% and 87.02%, respectively. It is also inferred that energy consumption during machining reduces with an increase in rake angle because of the sharpness of the cutting edge and less friction between tool and chip. An increase of nose radius and edge radius produces high thrust force and energy consumption and impedes high radial depth of cut. For the same machining parameters with the increase of edge radius and decrease of rake angle the mechanism of material removal changes from shearing to ploughing.