Experimental characteristic evaluation of micro hole EDM drilling of Ni51.58Ti48.34 alloy with copper electrode and response optimization using GRG assisted with GA

Abstract

Abstract Nitinol, a biocompatible material, is gradually becoming famous for its superelasticity, shape memory and corrosion resistance behaviours. However, the lower machinability due to the strain-hardening effect and lower thermal conductivity is contrary to its adventitious properties. Therefore, EDM is a preferable machining process for materials like Nitinol. EDM, thermal processing, raises the concern of processing Nitinol with minimal variation of its well-known properties and economical machining process. Therefore, this article deals with multi-objective optimization through GRG-assisted GA of µ-EDM drilling of Ni51.58Ti48.34 alloy using a copper electrode and distilled water. It was found that discharge current and servo voltage significantly influence the responses. The GA, with the assistance of GRG, optimized the multiple responses (viz. MRR, TWR and DoT) and yielded a discharge current of 12 A, gap voltage of 40 V, discharge time of 2 µs, charging time of 9 µs and flushing pressure of 50 kg/cm2. The confirmatory experiment yielded MRR of 0.0036 g/min, TWR of 0.0038 g/min and DoT of 0.0089 radians. There were variations of the predicted and experimentally validated responses by − 2.78, 26.32 and 35.96% for MRR, TWR and DoT, respectively.

Keywords

• EDM drilling
• Copper electrode
• Dielectric fluid
• Nitinol
• Grey relational grade
• Genetic algorithm