Experimental Investigation for improving the productivity, hole geometry and machined surface in EDM drilling of Ti-6Al-4V using desirability function approach (DFA)

Improving and controlling the quality of miniature holes is very challenging task. It is more difficult when the Ti-alloys are used for fabrication of aerial components due to their exceptional mechanical properties and strength. Moreover, they are chemically reactive with all tool materials in conventional machining. Hence, electrical discharge drilling (EDD) is the preferred choice to produce high-aspect ratio holes in these alloys. The behaviour of the EDD process is complex owing to spark ersion phenomennon. In the present study, an integration of Box-Behnken design (BBD) and desirability function approach (DFA) has been emplyoed to optimize the productivity, hole geometry and resolidified layer during EDD of Ti-6Al-4V. These perfoamnce cgaracteristics are quantified in terms of metal removal rate (MRR), hole taper (HT) and recast layer thickness (RLT). The influences of process variables (discharge current, pulse on and off time, dielectric pressure) on these responses have been analyzed using the response surface models. The application of DFA has reduced HT and RLT by 69.23% and 36.83%, respectively and MRR is enhanced by 62.54%. The approach can also be used to optimize the other machining surface parameters significantly.