Workpiece and electrode influence on micro-EDM drilling performance

In recent years, the need for products containing micro-features has shown a pronounced and steady growth in several fields of application. For the development of micro-holed devices, one of the most important technologies is micro-EDM (Electro Discharge Machining). Micro-EDM can be considered as an ideal process to obtain burr-free micron-size features with high aspect ratios. In particular, micro-EDM is a non-contact material removal process in which rapid electric spark discharges remove the material composing the workpiece by means of melting and vaporizing phenomena. The present work deals with the fabrication of micro holes using micro-EDM technology. The investigation focuses on the influence of different electrodes and workpiece materials on the process performance, expressed in terms of tool wear ratio. In particular, the influence of four different workpiece materials (stainless steel, titanium, magnesium and brass), three electrode materials (copper, brass and tungsten carbide) and two different electrode shapes (cylindrical and tubular) was investigated. Moreover, an analysis of the geometrical characteristics of the micro holes in terms of conicity and diametrical overcut was carried out. An influence of electrode geometries, electrode material and workpiece material on the final output was found.