PARAMETRIC OPTIMIZATION OF THE ELECTRICAL DISCHARGE DRILLING OPERATION OF TITANIUM ALLOY FOR HOLE DILATION AND DRILLING SPEED

Abstract

The electrical discharge drilling (EDD) process is an effective solution to produce small holes in difficult-to-cut materials. In this work, the EDD
parameters, including the current (I), the gap voltage adjustor (G), the pulse on time (Ton), and the pulse off time (Tof) are optimized to reduce the hole
dilation (HD) and increase the drilling speed (V). The EDD trials were conducted for the titanium grade 4 using the Box-Behnken method. The Gaussian
process regression (GPR) approach is used to develop the correlations of the EDD responses. Lastly, the best values for the EDD parameters were found using
the non-dominated sorting genetic algorithm II (NSGA-II). The results showed that the optimal I, G, Ton, and Tof are 13A, 8, 65μs, and 55μs, respectively.
The HD was reduced by 32.6%, while the V was enhanced by 76.7% at the optimal point, as compared to the initial values. The outcomes could be applied
to the practical EDD process of titanium grade 4 for improving the drilled quality and productivity. The proposed approach could be used to solve
optimization problems for other EDD processes.