An experimental investigation and statistical modelling for trim cutting operation in WEDM of Nimonic-90

Trim cutting operation in wire electrical discharge machining (WEDM) is considered as a probable solution to improve surface characteristics and geometrical accuracy by removing very small amount of work materials from the surface obtained after a rough cutting operation. In this study, an attempt has been made to model the surface roughness and dimensional shift in trim cutting operations in WEDM process through response surface methodology (RSM). Four process parameters; namely pulse-on time (Ton), servo voltage (SV), wire depth (Wd) and Dielectric flow rate (FR) have been considered as input parameters in trim cutting operations for modelling. Desirability function has been employed to optimize multi performance characteristics. Increasing the value of Ton, Wd and FR increases the surface roughness and dimensional shift but increasing SV decreases both surface roughness and dimensional shift. Quadratic models have been proposed for both the performance characteristics. In present experimentation, thickness of recast layer was observed in the range of 6?m to 12?m for low to high value of discharge parameters.