Wire-Electric Discharge Machining (W-EDM) is one of viable advanced machining techniques for machining of hard materials like Titanium alloys precisely.It is critical to determine the optimum settings for control parameters to achieve desired levels of surface finish and dimensional tolerance.Considering this, this research investigates the effects of current, pulse on time (Ton) and pulse off time (Toff) on surface roughness (Ra) of WED machined Ti-6Al-4V alloy.The study showed that, increase in current from 2 A to 6 A resulted in increase of Ra by 13.92 % and increase in Ton from 20 μs to 50 μs caused an almost linear increase in Ra by 8.95 %.But increase in Toff from 20 μs to 30 μs led to a sharp reduction in Ra by about 20.44 %.Further, a regression model is developed to predict the surface roughness with R2=72.5%.The machined surfaces are characterised by the presence voids and microcracks on the recast layers, formation of microglobules, ridges and craters due to thermal effects.Within the range of study Toff showed significantly larger influence on Ra compared to other parameters of the study.

Present research work is focused on investigation of material removal rate in Wire-ED Machining (EDM) of artificially aged Al-6061/ B4C reinforced composites with 2-6 wt.% in peak aged condition. Combined effect of B4C and artificial aging at 100 degrees C improved the hardness by 20 - 170% under as cast and artificially aged condition. Initially the wire EDM experiments are conducted on Al6061 alloy and then the process parameters such as current, pulse-on time (t(on)) and pulse-off time (t(off)) are optimized to obtain the high material removal rate (MRR). At optimized conditions test samples with various % of B4C are machined to study their influence on MRR. The study revealed that current and t(off) had a significant influence. MRR increased as current is increased and it decreased as t(off) is increased. Maximum MRR at optimum settings, current : 5.53 A, T-off : 10 mu s and T-on : 36.46 mu s is 2.45 mg/min. Considering the limitation of the experimental set up the modified optimum settings (T-off : 10 mu s, T-on : 30 mu s and current : 5 A) resulted in average MRR of 2.39 mg/min with deviation of 0.20 mg/min. The study showed that there is no significant difference in MRR and the morphology of the machined surface with respect to test samples of different % of B4C particles as reinforcement in Al6061 composite.

Wire electric discharge machining (WEDM) is one of the foremost methods which has been utilized for machining hard-to-cut materials like Titanium alloys. However, there is a need to optimize their important operating parameters to achieve maximum material removal rate (MRR). The present paper investigates the effect of control factors like current, pulse on time ( T on ), pulse off time ( T off ) on MRR of machining of Ti-6Al-4V alloy. The study showed that, increase in current from 2 A to 6 A results in a significant increase in MRR by 93.27% and increase in T on from 20 μs to 35 μs improved the MRR by 7.98%, beyond which there was no improvement of MRR. The increase in T off showed a counterproductive effect. Increase in T off from 10 μs to 30 μs showed an almost linear decrease in MRR by 52.77%. Morphological study of the machined surface showed that cut surface consists of recast layer on which microcracks were present, and revealed the presence of globules, ridge-structured formations of recast layers and voids. In addition, a regression model was developed to predict the MRR with respect to the control factors, which showed a good prediction with an R 2 value of 99.67%.