Experimental investigations and optimization of process variables of electro discharge coating process for Al-7075 alloy: a hybrid MCDM approach

Abstract

The present study aimed to improve and assess the electrical discharge coating (EDC) factors with aluminium 7075 alloy as a substrate. The results of input variables like current, composition, and compaction load on EDC responses, including material deposition rate (MDR), tool wear rate (TWR), and surface roughness (R_a) were studied. Taguchi’s L₉ experiment design was employed with GRA (grey relational analysis), ARAS (Additive Ratio Assessment), and preference value (K_i) was measured. The experiments determined the best parametric setting for more MDR, less TWR, and less R_a. The level of contribution of the process parameters to the response was evaluated by a statistical test known as ANOVA, wherein current appeared as the most noteworthy parameter, followed by composition and compaction load. The results of GRA and ARAS were compared with a prominent MCDM method known as TOPSIS, which substantiated the outcomes of both methods. Successfully attained rates for material deposition, tool wear, and average surface roughness were 0.385 mg/min for material, 4.37 mg/min for tool wear, and 2.101 µm for surface roughness. Finally, a sensitivity study is used to validate the hybrid model’s constancy with a strong correlation. The topography of the deposited surface was analyzed by SEM, wherein base material, deposition, and interface were distinctly visible with the occurrence of a few micro-cracks. The XRD contour of the coating exhibited peaks of Al, Al₂Cu, Cu, and SiC. Additionally, the pin-on-disc wear result yielded a substantial drop in the wear of the coated samples as compared to the substrate material.

Keywords:

• Gray relational analysis
• ARAS
• TOPSIS
• Taguchi’s design
• tribology

Acknowledgment

We are grateful to the Department of Mechanical Engineering, NIT Silchar and Production Engineering, NIT Agartala and also the CRF, NIT Agartala for providing lab space.

Disclosure statement

No potential conflict of interest was reported by the authors.