Design and implementation of new electrode geometries in electrical discharge drilling

This study introduces new electrode geometries to be used for drilling small-diameter holes on AISI 304 using Electrical Discharge Drilling (EDD) process. The aim was to improve flushing characteristics and debris removal during drilling. In addition to commonly used circular electrode, new electrodes having side-cut, elliptical, and square geometries were designed and implemented. A series of drilling operations were done at various conditions using such electrodes. Effectiveness of electrode geometry on drilling performance was investigated in terms of Material Removal Rate (MRR), Electrode Wear Rate (EWR), and Tool Wear Ratio (TWR). Dimensional features and surface quality of drilled holes were evaluated with respect to Overcut (OC), Aspect Ratio (AR), and Surface Roughness (SR). 3D three-phase models were developed using Computational Fluid Dynamics (CFD) for simulation of flow field at inter-electrode gap. Multi-objective optimization of outputs of EDD process using side-cut electrode was implemented by Response Surface Methodology (RSM) coupled with Desirability Function (DF) technique. The results revealed that side-cut and elliptical electrodes are the most preferable for producing holes having good dimensional accuracy and improved surface quality at high drilling rates. Such electrodes also exhibit good flushing performance.