Optimization of Wire Electrical Discharge Machining of Inconel-625 for Minimum Surface Roughness and Maximum Material Removal Rate

Abstract

Inconel-625 is a nickel-alloy based material with properties such as high hardness, oxidation resistance, and high fatigue strength. These properties make it suitable for applications in power generation, marine, and aerospace industries. Due to high hardness of the material, it is di cult to machine it by conventional machining methods such as turning, milling or grinding. For this reason, Wire Electrical Discharge Machining (Wire EDM) is adopted as an alternative method to machine the material. The competences of this machine includes the fact that it is able to make straights cuts for surface roughness measurement, as opoposed to Sinker EDM which is speci ed in making internal cuts. Once selecting wrong control parameter-levels, the method is accompanied with challenges such as wire breakages, short circuiting of wire, poor surface nish and low material removal rate, leading to high production cost. In this research, experimental investigations were done to know the in uence of pulseon time (ton), wire feed rate (fw) and gap voltage (vg) on surface roughness (SR) and material removal rate (MRR). An Algorithm was developed from mathematical model, developed using Response Surface Methodology (RSM), to correlate input control parameters with output performance measures. The machining process was optimized using Taguchi optimization technique. Inconel-625 plates of 10 mm thickness were used as specimen in experimental work. It was found out that, for machining of Inconel-625 using wire electrical discharge machining, brass wire as cutting wire, and de-ionized water as medium uid, the minimum surface roughness can be achieved for pulse-on time, wire feed rate, and gap voltage of 0.4 s, 8 mm/min, and 68 V, respectively, whereas for maximum material removal rate, the pulse-on time, wire feed rate and gap voltage should be 0.6 s, 10 mm/min, and 56 V, respectively. For improved material removal rate and surface roughness, it was observed that the pulse-on time, wire feed rate, and gap voltage could be 0.5 s, 8 mm/min, and 62 V, respectively. The optimization improved surface roughness and material removal rate by 5.68 % and 3.041 %, respectively. It is recommended that other output performance measures such as kerf width, corner accuracy and dielectric uid ow rate may be considered for further investigations.