Experimental Investigation on Surface Characteristics in Powder-Mixed Electrodischarge Machining of AA6061/10%SiC Composite

In this study, machining of AA6061/10%SiC composite fabricated by mechanical stir casting process has been experimentally investigated using electrodischarge machining (EDM) process with tungsten-powder-mixed dielectric fluid (PMEDM). Peak current, pulse on-time, pulse off-time, and gap voltage are selected as machining parameters. Mathematical relation has been established for response quality characteristics like surface roughness with and without tungsten powder dielectric fluid using Central Composite Rotatable Design (CCRD) through response surface methodology (RSM). Surface characteristics like microhardness, surface topography, and white recast layer have been evaluated through scanning electron microscope (SEM), electrodispersive X-ray spectroscopy (EDS), and micro-Vicker hardness. Results have also been compared with simple EDM of AA6061/10%SiC composite without powder-mixed dielectric fluid. The existence of tungsten powder in dielectric fluid increases surface quality owing to decrease in number, size, and depth of craters formed while machining. Thickness of white recast layer is reduced whereas surface hardness is increased when machined with powder-mixed EDM.