Experimental study on effect of geometry and material of tubular electrode in electrical discharge drilling of tungsten carbide

Abstract Machining of WC material presents a challenge due to its specific properties, particularly high hardness and brittleness. The Electrical Discharge Drilling (EDD) process is preferred for the production of small-diameter holes on difficult-to-cut materials. This study presents an experimental investigation of the effects of tool electrode geometry and material on the drilling performance and hole accuracy of WC-26%Co. Blind holes were produced under specific process conditions using tubular electrodes made of brass and copper, featuring single and multiple channels. The Material Removal Rate (MRR) and Electrode Wear Rate (EWR) were measured as process outputs to evaluate the impact of electrode material and geometry on drilling performance. Hole accuracy was also assessed based on the shape of drilled holes as well as enlargement in hole diameter, referred to as Overcut (OC). The set of experiments with utilization of each geometry and channel configuration of tool electrode were repeated for three times, and the results indicated good reliability. Compared to the single-channel electrode, the central protrusion at the hole center was significantly eliminated with the use of the multi-channel electrode, resulting in improved drilling performance as well as the achievement of an accurate hole shape. Among the average values of results from all sets of experiments, the multi-channel brass electrode provided the highest MRR (74.31 mg min −1 ), EWR (30.57 mg min −1 ), and OC (20.60%) with an accurate shape. Furthermore, the surfaces of holes drilled by multi-channel electrodes are relatively cleaner and more uniform due to less pronounced surface anomalies.