A study on effect of dead metal zone on tool vibration, cutting and thrust forces in micro milling of Inconel 718

Abstract

Inconel 718 is a nickel-based super alloy, its characteristics pose more complex in micro machining. Aim of the present study is to investigate effect of process parameters and tool parameters on the dead metal zone (DMZ) geometry and length of shear plane and further on cutting force, thrust force and amplitude of cutter vibration. In the present study, mechanistic models were integrated with finite element method (FEM) simulation to predict cutting force and thrust force in micro milling of Inconel 718. Numerical simulation was carried out to estimate size of DMZ and its angles for all the experiments. Simulation results were used in the mechanistic models to estimated cutting force and thrust force. Series of experiments were carried out on the Inconel 718 at different levels of process and tool parameters and cutting forces were measured. Comparison between the predicted values of cutting forces and thrust forces with experimental results shown a good agreement. Effect of process and tool parameters on size of DMZ and length of shear plane was studied. Further, effect of DMZ and length of shear plane on cutting force, thrust force and amplitude cutter vibration was studied. Feed per tooth and cutter nose radius have significant effect on length of shear plane and length of DMZ side respectively. The parameters were optimized as 4500 rpm of cutting speed, 10 μm per tooth of feed, 0.12 mm of cutter nose radius and 6.8485° of rake angle for minimum side length of DMZ and length of shear plane in order to reduce cutting force, thrust force and amplitude of cutter vibration.