Investigation and Optimization of Process Parameters in Electrical Discharge Machining (EDM) Process for NiTi 60

Nickel-titanium is one kind of smart material alloy; it is capable to regain its earlier shape when heated. The machinablity constraints arises with the use of conventional machines while machining of NiTi alloys such as high tool wear, adverse chips, formation of burr after machining and grinding. To overcome these difficulties non-conventional machining process, electrical discharge machining (EDM) are used. In this research, the effect of process parameters such discharge current (A), gap Voltage (V), pulse on time (Ton) and pulse off time (Toff) on the performance parameters like material removal rate (MRR), surface roughness (SR) and white layer thickness (WLT) has been investigated for NiTi60 (Smart Material Alloy). Design of Experiments was conducted by Taguchi's method by considering orthogonal array of L27 and using Minitab software. The process parameters set during the performance of experiments are Current 4, 6, and 8 A, Voltage 40, 55, and 60 V, pulse on time 20, 40, 60 mu s, and Pulse off time 5, 7, 9 mu s. The corresponding performance values obtained for MRR was 0.155 to 1.24 mm(3) min(-1), SR was 1.597 to 7.474 and WLT was 5 to 20 mu m. Process parameters of optimum settings are developed for each performance parameters and based on these optimum setting confirmation test were conducted which shows that, the percentage of error obtained for material removal rate was 7.63%, 2.49% for surface roughness and 2.86% for white layer thickness.