MULTI RESPONSE OPTIMIZATION OF WIRE ELECTRICAL DISCHARGE MACHINING OF NITRONIC-30 BY USING COATED WIRE MATERIAL FOR AUTOMOTIVE APPLICATION

Abstract

In order to make the machining process sustainable, uninterrupted machining is crucial to minimize cutting time and energy requirements. It is essential to understand the reasons and mechanisms influencing wire failure in order to save machining time, conserve resources, and enhance sustainability. Different electrode materials perform differently due to variations in conductivity, composition, and tensile strength. Thus, a thorough comparative investigation was conducted to understand the impact of zinc-coated wire, diffused wire, and gamma-coated wire during WEDM of Nitronic-30. The investigation involved measuring the material removal rate (MRR) and surface roughness (SR) for different input parameters like pulse on time (Ton), pulse off time (Toff), peak current (IP), and servo voltage (SV). Surface morphology analysis, recast layer thickness analysis were performed to compare and comprehend the performance of wire electrode materials. The findings revealed that zinc-coated wire material was not suitable for machining due to multiple wire breakage incidents. Gamma-coated wire emerged as the ideal candidate, exhibiting a significant improvement in MRR, with 28.84% more compared to diffused wire. However, diffused wire showed promising results in terms of surface roughness. Furthermore, economic justification indicated an 18.87% cost saving with the use of gamma-coated wire. Surface morphology analysis showed minimal surface defects for diffused wire, while the defects gradually increased for zinc-coated wire and gamma-coated wire. The mathematical model developed by response surface methodology shows very good prediction of output responses. Also, the finite element thermal modeling of the process has been done by considering important aspects such as energy distribution factor, Gaussian heat distribution and latent heat of fusion to predict thermal behavior as well as material removal mechanism in WEDM process. Validation of model MRR with experimental MRR shows very good agreement.