Abstract
This paper reports the effect of process parameters on material removal rate (MRR) and
surface roughness (Ra) in wire electro discharge machining of AISI D2 steel. The
experiments were performed by different cutting conditions of pulse on time (Ton), pulse
off time (Toff), servo voltage (SV) and wire feed (WF) by keeping workpiece thickness
constant. Taguchi L27 orthogonal array of experimental design is employed to conduct the
experiments. Multi-objective optimization was performed using Taguchi based utility
approach to optimize MRR and Ra. Analysis of means and variance on to signal to noise
ratio was performed for determining the optimal parameters. It reveals that the
combination of Ton3, Toff1, SV1, WF2 parameter levels is beneficial for maximizing the
MRR and minimizing the Ra simultaneously. The results indicated that the pulse on time
is the most significant parameter affects the MRR and Ra. The melted droplets, solidified
debris around the craters, cracks, and blow holes were observed on the machined surface
for a higher pulse on time and lower servo voltage. Recast layer thickness increased from
an increase in pulse on time duration. The machined surface hardness of D2 steel is
increased due to the repetitive quenching effect and formation oxides on the machined
surface.