Machining of Micro Holes In Titanium Alloy By Electro Discharge Machining

Titanium alloys, particularly Ti-6Al-4V, are widely employed in aerospace, biomedical, and high-performance engineering applications due to their excellent strength-to-weight ratio, corrosion resistance, and biocompatibility. The study employed a systematic experimental approach using a Taguchi L9 orthogonal array to investigate the influence of key EDM parameters, namely pulse current, pulse on-time (Ton), pulse off-time (Toff), discharge voltage, and dielectric flushing pressure. The experiments were conducted on Ti-6Al-4V plates using specially fabricated copper-tungsten (Cu-W) composite electrodes developed through powder metallurgy to combine copper’s high electrical conductivity with tungsten’s high melting point. This composite structure aimed to reduce tool wear and provide stable, uniform spark discharges essential for micro-machining. Microscopic and SEM analyses further revealed that stable discharge conditions minimized recast layer thickness and mitigated micro-crack formation, while excessive energy inputs resulted in porous surfaces and structural irregularities. The use of Cu-W electrodes contributed to approximately 30% lower TWR compared to pure copper electrodes, supporting more consistent hole geometry and dimensional accuracy. The research also recommends adopting strategies such as nanoparticle-enhanced dielectric fluids and multi-pass EDM finishing to further refine hole quality. Implementing a two-pass strategy reduced taper from 1.4° to 0.8° and improved roundness tolerance from ±12 µm to ±5 µm. Post-process ultrasonic cleaning additionally enhanced surface quality by removing residual micro-debris and slightly reducing roughness.