Experimental investigation of hole geometry during electric discharge drilling of aerospace material sheet

Abstract

In this research paper experimental investigation of hole geometry during electric discharge drilling (EDD) is reported on Arial material Inconel-718. Electric discharge drilling is extensively used for aerospace equipment and component manufacturing. Proper geometry and close dimensional tolerance play a very important role during operations and functioning of aerospace parts. One of the important application of electric discharge drilling is in creating cooling hole in gas channels of gas turbine engines and similar other high temperature applications. In order to understand the parametric effect on hole geometry during electrical discharge drilling on Inconel-718, experiments are conducted according to the Box-behnken design of experiments. Four main electric discharge drilling parameters considered: Flushing pressure, Discharge current, Pulse on time and Duty cycle factor. Parametric effects and their interactive influence on hole geometry are studied by plotting contour plots. Favourable range of process parameter: Flushing pressure (kPa): 26 – 30, Discharge current (amp): 2–2.5, Pulse on time (µs): 6 – 6.5, Duty cycle factor (%): 50 – 55. After validating the established favourable range, improved hole geometry in term of better circular hole is observed in range of 0.989 to 0.992. Reported results can be useful to aerospace equipment manufacturers for getting improved geometry of drilled hole and also main recommendation is useful developing efficient automation of EDD process for quality production.