Measurement and optimization of multi-response characteristics in plasma arc cutting of Monel 400™ using RSM and TOPSIS

Abstract

Plasma arc cutting (PAC) is well recognized non-conventional machining processes widely used to fabricate intricate part profiles for diverse electrically conductive materials including superalloys and composites. The dimensional accuracy and surface quality of PAC surface are critical elements for specific applications especially in aerospace and manufacturing industries. Material removal rate (MRR), kerf taper (KT) at top and bottom surface and heat affected zone (HAZ) are very important attributes which influences the quality and performance of plasma cut surfaces. Present study investigates the effect of PAC parameters such arc current, cutting speed, stand-off distance and gas pressure on evaluating the part quality characteristics such as MRR, KT and HAZ of Monel 400 superalloy. Box-behnken design approach is incorporated to formulate the experiments and rigorous experimental analysis is performed. The quadratic models are developed and assessed for its performance using analysis of variance (ANOVA). Statistical and response surface analysis are accomplished to identify the most influencing PAC parameters. Multi-objective optimization studies are carried out using Multi-criteria decision making methodology (MCDM) to determine the optimal cutting conditions of PAC through employing technique for order of preference by similarity to ideal solution (TOPSIS). The optimal PAC process parameters such as cutting speed of 2400 mm/min, gas pressure of 3 bar, arc current of 45 A and stand-off distance of 2 mm are determined. Microstructure analysis is conducted to ascertaining the morphologies of cut surface at various cutting conditions.