Performance of Used Transformer Oil as Dielectric Media During EDM of Inconel 718 Super Alloys

Abstract

Application potential of used transformer oil as dielectric media has been experimentally studied during electro-discharge machining of Inconel 718 super alloys. Experiments have been conducted by varying peak discharge current and pulse-on duration; the following performance measures material removal efficiency, surface roughness, surface crack density and white layer thickness etc. have been studied. Improvement in EDM performance in purview of material removal rate, morphology and topography of the machined surface has been discussed while using used transformer oil (as dielectric) instead of kerosene. Topography of the EDMed surface has been analyzed in detail which has included surface roughness, metal migration, phase transformation, grain refinement, formation of intermetallic compounds, residual stress and micro-hardness. Overall, it has been included that application of used transformer oil has offered potential benefit as compared to kerosene dielectric media to facilitate machinability of ‘difficult-to-cut’ material Inconel 718 during electro-discharge machining.