NDEDM of Hastelloy using CNT-incorporated dielectric medium utilizing composite electrodes

This study examines Electric Discharge Machining (EDM) of Hastelloy, a nickel-based superalloy, using Near-Dry EDM (NDEDM) and conventional EDM with hydrocarbon oil. Composite electrodes made from Friction Stir Processing and Stir Casting were tested to assess the effects of CNT concentration, current, pulse-on time, and gap distance on material removal rate, tool wear rate, and surface roughness. Optimal CNT attention of 2 g/l in NDEDM increased MRR to 0.6 mm³/min and reduced TWR to 0.26 mm³/min and Ra to 1.4 µm. Copper composite electrodes outperformed aluminum composites by 20% in MRR due to better conductivity and stability. Discharge currents of 32 A increased MRR but also TWR; 30 µs pulse-on time offered the best balance between removal and erosion. Surface morphology analysis revealed uniform crater formation and minimal microcracking under optimized conditions. NDEDM exhibited 15% improvement in surface integrity compared to conventional EDM, showing its potential for precision machining applications.