Electrical discharge drilling of WC-Co15: Modeling and multi-objective optimization based on response surface methodology

Non-traditional machining methods are preferred for machining of ceramics because of material specifications. Electrical discharge drilling (EDD) is a process used to produce holes with small diameters. This research presents the methodology for modeling and multi-objective optimization based on response surface methodology for EDD of WC-Co15. An experimental plan was constructed based on the design of experiment technique, namely Box–Behnken design. Drilling operations were conducted at specified levels of electric current, pulse-on time, and pulse-off time with utilization of multi-channel brass tubular electrodes having an outer diameter of 1 mm. The process performance was evaluated on the basis of material removal rate (MRR) and electrode wear rate (EWR) as well as the quality of drilled holes on the basis of overcut (OC) and surface roughness (Ra). Each output was modeled in accordance with the experimental results. The multi-objective optimization of all outputs was performed based on overall results. Analysis of variance, response surface regression analysis, and response surface optimization were conducted to procure the optimum drilling conditions with the aim of achieving the highest MRR with the lowest EWR, OC, and Ra.