Material-Technology Index to evaluate micro-EDM drilling process

This research aims to study the influence of the process parameters and the thermal and electrical properties of workpiece and electrode materials on the performance of micro-EDM drilling. An experimental campaign was carried out using different workpiece materials such as stainless steel, tungsten carbide and aluminum and as electrode materials tungsten carbide and brass. Material Removal Rate (MRR) and Tool Wear Ratio (TWR) were assumed as performance indicators. The geometrical characteristics of micro-holes were evaluated by taking into account Diametral Overcut (DOC) and Taper Rate (TR). A “Material-Technology Index” (MTI), taking into account EDM process parameters, electrical and thermal properties of workpiece and electrode materials, was defined for each indicator. The effect of the MT indexes on the process performance and geometrical indicators was studied and proper fitting equations, having satisfactory coefficients of determination, were used to summarize the analyzed behaviors. Finally, a surface integrity analysis was carried out on the micro holes obtained in different conditions.