Study of machinability assessment of nickel based alloy using electro-discharge machining with transformer oil as dielectric

Abstract

Feasibility study of transformer oil as dielectric media was carried out for electro-discharge machining of difficult-to-cut Inconel 718 super alloy. Experiments were accompanied with copper tool electrode by opting peak current (Ip) and pulse-on time (Ton) as variables. After executing experiments, process responses like Material Removal Rate (MRR), surface roughness (Ra), Surface Crack Density (SCD) and White Layer Thickness (WLT) were evaluated. Additionally, phase analysis and residual stress were computed. These data helps to explain the development of surface cracks and white layer on machined surface. Performance of transformer oil was compared with kerosene dielectric media. It was noticed that application of transformer oil offered potential benefit in terms of improved MRR, reduced Ra as well as SCD. However, thicker white layer was credited on EDMed surface when transformer oil was used as dielectric media. The concept promotes eco-friendly and economic execution of EDM operation.