Multi-objective optimization of WEDM process parameters of Ti_(49.4)-Ni_(50.6) shape memory alloy for orthopaedic implant application

摘要

Purpose: This paper focuses on the investigation on the effect of process parameters such as pulse on time (T_(on)), pulse off time (T_(off)), spark gap set voltage (SV), wire feed (WF) and wire tension (WT) on the responses such as the material removal rate (MRR), surface roughness (SR), kerf width (KW) and dimensional deviations (DD) of Ti_(49.4)Ni_(50.6) (at.%) shape memory alloy (SMA) machined by WEDM. Ti-Ni SMA has fascinating properties and biocompatibility, it is considered for the present work.Design/methodology/approach: As per the Taguchi technique, L18 orthogonal array experiments on WEDM have been performed. The signals to noise (S/N) ratio plots are analysed to determine the influence of process parameters. Analysis has been tested through analysis of variance (ANOVA). SEM images are taken to confirm the results offering better surface quality. Findings: It was observed that pulse on time is the most significant factor for MRR and SR with the contribution of 35.69% and 59.02% respectively. The SV is a significant factor for KW and DD with contributions of 47.35% and 30.03% at 95% confidence level. A multi-response optimization has been carried out using grey relational analysis (GRA) to determine the optimum combination of process parameters. It is shown that, through GRA the optimal machining parameter setting such as A2B1C3D2E1 i.e. (pulse on time of 115 machine unit, pulse off time of 20 machine unit, spark gap set voltage of 90 V, wire feed of 6 m/min and wire tension of 3 machine unit) has been observed for maximum MRR and minimum SR, KW and DD. Young's modulus checked for biocompatibility.Research limitations/implications: Heat treatment process like annealing is found to be most suitable to recover shape memory effect of WEDMed samples.