Abstract
In the present work, an experimental investigation on wire electrical discharge machining (WEDM) of Monel-400 has been presented. Monel-400 is a nickel–copper-based alloy, mostly employed in ships and corrosion-resisting applications. Four input WEDM parameters namely discharge current (Ip), pulse-on time (Ton), pulse-off time (Toff) and servo voltage (SV) have been investigated and modeled for two performance characteristics namely machining rate (MR) and surface roughness (SR). Effect of WEDM parameters has been discussed using response surface graphs. Using analysis of variance, quadratic model is found significant for MR while two factors interaction (2FI) model has been suggested for SR. To optimize multi-performance characteristics, desirability function has been employed. Corresponding to highest desirability, the optimal combination of discharge parameters is Ip: 103 A; Ton: 113 μs; Toff: 37 μs and SV: 50 V. The effect of discharge energy on surface morphology has also been examined. High discharge energy increases the extent of surface damage and results in large size and overlapped craters on machined surface. Low discharge energy and high value of Toff result in minimum defects on machined surface. Trim cutting operations were performed at low discharge energy using different wire offset values. Result shows that surface finish can be improved significantly after a single trim cut irrespective of high discharge energy in rough cut.
Highlights
Monel-400 is a solid solution of nickel and copper, having high strength and toughness over a wide temperature range.Because of its high resistance to corrosive and most acidic environment, Monel has been widely used in chemical industries, food processing industry, heat exchanger tubing, nuclear reactors, sub-marine and ship propellers, etc.(Shoemaker and Smith 2006).Surface integrity of a machined component significantly affects its performance such as fatigue life, creep and corrosion
Quadratic model is found significant for machining rate (MR) while two factors interaction (2FI) model has been suggested for surface roughness (SR)
After modeling the machining characteristics in rough cutting operation, trim cutting operations have been performed at low discharge energy and different wire offset values to examine the effect of trim cut on final surface finish of the work material
Summary
Monel-400 is a solid solution of nickel and copper, having high strength and toughness over a wide temperature range. Investigated the significant machine parameters which are affecting the characteristics of microholes in nickel alloy in terms of microhole expansion, electrode depletion and material removal rate. Previous investigations show that the discharge current and pulse-on time are the most important parameters in WEDM that significantly affect the material removal rate and surface characteristics of the machined component (Shivade and Shinde 2014). To obtain high material removal rate, high discharge energy is required which results in high heat generation across the work material and wire electrode. After modeling the machining characteristics in rough cutting operation, trim cutting operations have been performed at low discharge energy and different wire offset values to examine the effect of trim cut on final surface finish of the work material.
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