Comparative performance evaluation and economic assessment between traditional and vibration assisted EDM during machining of Inconel 718

Abstract

Nickel based superalloy, Inconel 718 offers extensive applications in aerospace and gas turbine industries because of its outstanding properties, enabling high performance in various critical components. Despite the wide application of electric discharge machining (EDM) for difficult-to-cut conductive materials, the process becomes less productive due to unstable arcing and inadequate debris flushing during machining, leading to reduced operational efficiency. This research focuses on comparative performance evaluation and economic assessment between conventional-EDM and vibration assisted EDM (VA-EDM) while machining Inconel 718 with copper electrode. The workpiece was excited to vibrate with low frequency by employing unbalanced mass attached in a rotary motor with the aim of enhancing EDM performance. Material removal rate MRR, surface integrity (surface crack density SCD, surface roughness Ra, white (recast) layer thickness WLT) and tool wear rate TWR are analyzed to determine machining performance in comprehensive analysis. The results of the performance comparison show that vibration assisted is superior to the conventional-EDM process concerning enhanced material removal rate, and surface morphology with minimum surface crack density, tool wear rate and white layer thickness. The mean value ratios for Ra EDM/ Ra VA-EDM, TWR EDM/ TWR VA-EDM, WLT EDM/ WLT VA-EDM, and SCD EDM/ SCD VA-EDM are 1.35, 1.52, 1.21, and 1.74, respectively. Additionally, the surface integrity was enhanced using vibration-assisted EDM because it (a) increases the plasma flushing efficiency and the gap pressure gradient; (b) raises the energy of electrically charged plasma particles; (c) increases the effective flow of dielectric in the gap; (d) minimizes the number of ineffective pulses (short-circuiting and arching) on the surface; and (e) improves the dielectric flushing conditions in sparking gap. According to the findings, the overall machining expenditure per part under VA-EDM in Indian rupees (INR) 534 is lowered by 8% than expenditure under conventional-EDM (INR 576.60). The outcomes of this research have the potential to benefit numerous industries that deal with difficult-to-cut materials.