Investigation of micro holes fabrication via metal extrusion (MEX) additive manufacturing for micro EDM manufacturing

Tool electrodes for micro-EDM (Electro-Discharge Machining) are often made of copper and can have complex geometries with internal channels for dielectric fluid flushing. Metal Extrusion (MEX) Additive Manufacturing has the potential to successfully fabricate parts with intricate geometries, good dimensional accuracy, and low porosity, and it has proved to be promising in manufacturing copper electrodes for the EDM process. However, the capability of internal channel manufacturing for the dielectric flushing improvement and the performance of the printed micro-electrodes in the field of micro-EDM were not thoroughly investigated. The ultimate goal is to apply the MEX process to produce copper parts with internal channels, which will be finished by wire EDM before being used as electrodes in the micro-EDM. To this end, the possibility of manufacturing copper parts with through holes with a high aspect ratio and the influence of MEX process parameters were investigated by employing specifically designed test parts. The experimental results pointed out that the 0.129 mm layer thickness allows the fabrication of smaller holes than 0.089 mm. Deeper holes have smaller section sizes, and smaller holes show a lower dimensional accuracy. The achieved hole area resolution is about 0.03 mm2, but square holes exhibit a lower resolution of 0.15 mm2.