Influence of silicon carbide mixed used engine oil dielectric fluid on EDM characteristics of AA7075/SiCp/B4Cphybrid composites

Abstract

In this study, AA7050/SiC/B4C hybrid composites were machined using the Electric Discharge Machining process, used engine oil as the dielectric fluid to obtain wealth from waste. The experiments were conducted by varying Silicon Carbide (SiC) powder concentration, electrode material (copper and brass), discharge current, pulse on time and reinforcement wt%. The Material Removal Rate (MRR), Tool Wear Rate (TWR), Surface Roughness (Ra) and machined surface hardness were recorded as responses. The inclusion of SiC particles increases the MRR because of the bridging effect, whereas the Ra value was improved due to the complete flushing of the dielectric fluid. Owing to the existence of carbon content in used engine oil, black spots were found on the machined topography. The specimens machined with a brass electrode offer better machining performance as compared with those machined with a copper electrode. The results revealed that the MRR, TWR and Ra upsurge with the intensification of discharge current and pulse on time. Owing to the absence of a re-melted layer, composites with lower machined surface hardness have a higher surface finish. The parameters were optimized using the TOPSIS method, and it was found that under used engine oil dielectric medium with a powder concentration of 3 g l-1, parametric value sets of pulse on time 45 s, current 6 A, and machined with brass electrode offers superior machining efficiency.