Electric Discharge Machining of AA7075/SiCP/B4CP Hybrid Composites machined with Al2O3 Mixed Used Engine Oil Dielectric fluid

Machining hybrid composites through conventional machining technique was a challenging task as it produces excessive tool wear and exhibits poor surface roughness. In this research work, an attempt was made to electric discharge machining of AA7075/SiCP/B4CP Hybrid Composites produced through the stir casting route. The used engine oil was as the dielectric fluid with the objective of obtaining wealth from waste. The experiments were performed by varying distinct Electric Discharge Machining (EDM) process parameters with the goal of obtaining a high Material Removal Rate (MRR), low Tool Wear Rate (TWR) and least Surface Roughness (Ra). The experimental runs were optimized using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) optimization techniques. Experimental runs were designed using the L20 Taguchi orthogonal array in which Powder concentration, Current and Pulse on time were varied for three different levels, and two various dielectric fluids were used for investigation. The characteristics of the Used Engine Oil (UEO) were assessed to find its feasibility as a dielectric fluid. In comparison to EDM oil, the specimen machined in UEO dielectric medium has a somewhat greater MRR. Regardless of the kind of dielectric fluid employed, adding Al2O3 particles increases the MRR because of the bridging effect. Due to its high thermal conductivity, UEO oil produced electrodes with a TWR that was greater than that of EDM oil. The TWR decreases with the addition of Al2O3 particles due to an increase in the spark gap. In comparison to EDM oil, the specimen machined under UEO displays a lower Ra value. Ra decreases with the inclusion of Al2O3 particles due to the thorough flushing of machining waste. The specimen machined under Al2O3 mixed UEO dielectric medium, with the process parameters tuned at 3A current and 20µs Ton, offers better machining performance and was recommended for EDM sector.