Evaluation of Micro Electro Discharge Machining Performance: the Effect of Process Parameters and Electrode Material

The miniaturization of components enhances the difficulties related to their production with conventional technologies. At the same time this miniaturization trend opens the possibility to employ new non-conventional technologies that, like micro-EDM, are able to fulfil the market requirements and the technological challenges associated with the realization of micro components. Micro-EDM is able to machine any conductive material regardless of the hardness and high strength of the workpiece material and, thanks to the contact-less nature of the process, it leaves no residual stresses in the workpiece. This technology allows the realization of high aspect ratio micro features, especially micro holes, with an excellent surface finishing. The influence of the process parameters is of great importance for an effective control of the wear phenomenon and also because they have an influence on the final geometrical characteristics of the through holes and on the process performances. The aim of the present work is to deepen the knowledge about the influence of the process parameters on the final geometrical characteristics of the holes and on the process performances. A signal acquisition system, aimed at the recording and filtering of the process parameters, was implemented. The data collected with the acquisition system has been analysed, in order to obtain reliable information about peak current, peak voltage, number of sparks, energy and power exchanged during the process. Once the data has been collected for all the electrode materials and diameters and for all the process parameters combinations, a regression analysis has been carried out. Predictive linear and non-linear equations based on the measured values of the process parameters were obtained in order to forecast the machining time and the electrode wear, as well as the geometrical characteristics of the holes.