A novel approach towards sustainable electrical discharge machining of metal matrix composites (MMCs)

It is a daunting challenge to improve the sustainability of electrical discharge matching (EDM) as well as to make the process environmentally friendly. This paper carried out investigations into the role of steam as a dielectric medium during sink (EDM) of aluminum-based metal matrix composite (MMC) and critically compares the outcome with that of widely used hydrocarbon-based dielectrics such as kerosene in terms of output parameters, positive environmental aspect, and cost-effectiveness. The output parameters such as recast layer, material removal rate (MRR), and machined surface characteristics were analyzed in details. The recast layer obtained upon steam dielectric EDM was significantly improved by 37.15% in terms of thickness, bonding with base metal as well as structure and morphology. This favorable development was attributed towards high temperature, low heat spark material erosion, and low conductivity of steam as a dielectric medium. The machined surface upon steam dielectric EDM apparently contained machined debris rather than solidified molten workpiece material and contributed towards minimum roughness by 1.5 times due to high temperature, high pressure, and low viscosity of the steam. It is found that the ongoing cost of sink EDM can be reduced to one-fifth if the hydrocarbon-based dielectric is replaced by steam.