Surface defects in PMD-EDM of titanium alloy Ti-6246

Abstract

Titanium alloys which are categorized as lightweight materials, poses greater strength and toughness are usually known to create major challenges during machining. Electrical discharge machining (EDM) which is very prominent amongst the non-conventional machining methods is expected to be used quite extensively in machining titanium alloys. EDM process is known to cause surface damaged layers which consists of three types of surfaces; spattered, recast and heat affected zone. This project was undertaken to study the machining performance of EDM and powder mixed dielectric-electrical discharge machining (PMDEDM) in machining Ti-6246 with respect to the surface integrity of machined surface by using copper tungsten (CuW) electrode. The machining parameters considered are voltage (V), current (I), pulse on time(Ton), interval time (Toff) and concentration of the SiC powder (C) in dielectric fluid. The respected responses investigated include surface alteration and overcut. It was found that PMD-EDM process produced less damaging effect on the surface layer of the machined surface and widened the overcut.