Characterization of surfaces obtained by micro-EDM milling on steel and ceramic components

This work deals with the execution of micro-pockets on two different materials (AISI 316 L stainless steel and ZrC+10MoSi2UHT ceramic) using micro-EDM milling. The experiments were carried out by varying process parameters supposed to influence the surface quality, namely discharge pulse-on-time, peak current, voltage, and frequency. For both materials, tungsten carbide cylindrical electrodes were used. The investigation focused on the different results obtained in terms of surface roughness (Sa), kurtosis (Sku), and skewness (Ssk) to evaluate the different finishing level of the surfaces obtained as function of the process parameters. The aim of the present paper is to propose a method for studying the surface characteristics in terms of peaks and valleys shape and distribution, with respect to the mean line, according to ISO 25178. The results of this analysis can provide important information when designing micro-EDM milling processes.