Effect of single and multi-channel electrodes application on EDM fast hole drilling performance

This paper presents a comparative experimental investigation of electrical discharge machining fast hole drilling of aerospace alloys, namely Inconel 718 and Ti-6Al-4V. A series of experiments was carried out using electrical discharge machining process in order to explore the influence of electrode type and material, i.e., single and multi-channel tubular electrodes made of brass and copper materials. The comparisons were made from the results of material removal rate, electrode wear, microhardness, and scanning electron microscope images taken from the machined/drilled hole surfaces. The experimental results reveal that the single-channel electrode has comparatively better material removal rates and lower electrode wear ratio. However, scanning electron microscope images show that multi-channel electrodes produce better surfaces than single-channel electrodes for both aerospace alloys. Microstructural changes while drilling operations for both types of electrodes result in an annealing effect on Inconel 718 and a tempering effect on Ti-6Al-4V alloy. In addition, multi-channel electrodes produce comparatively lower hardness values.