Multi-response optimization of process parameter influencing Surface Roughness, Kerf Width and MRR during machining of NIMONIC C-263 by WEDM

Abstract

Wire Electrical Discharge Machining (WEDM) is a metal-working process whereby material is removed from a conductive work piece by electrical erosion. This project work focuses on finding out the optimum parameters in Wire - EDM for machining of NIMONIC C-263. The major application of the NIMONIC C-263material is in the aerospace industry, selling ring and aerospace turbine. Input process parameters that are taken into consideration are Pulse on time, Pulse off time, Servo voltage and wire tension. Output parameters are Material removal rate (MRR), Surface roughness (SR) and Kerf width (KW) is measured. Wire material like Zn-Coated Brass wire is used in this experiment. For design of experiment Taguchi methodology of L16 orthogonal array is used. And optimization of parameters is done with the help of Grey relational analysis (GRA). Pulse-on time (TON) was found to be the most significant factor for all the response variables such as MRR, Kerf width and SR at 95% confidence level, with percentage contributions as 82.79 %, 39.97 % and 38.38 % respectively. Surface roughness improves with increase in pulse-off time because with too short pulse off time there is not enough time to clear the melted small particles from the gap between the wire & work piece. Servo voltage has little effect on MRR but it has more effect over kerf width and SR. Surface roughness reduces with increase of servo voltage.