Study on Zirconium Boride Machined by Micro-EDM

The present research is focused on the application of micro-Electrical Discharge Machining technology on advanced ceramic materials, called Ultra High-Temperature Ceramic (UHTC). Nowadays, ceramics are very attractive materials because of their excellent mechanical and thermal properties, but they are extremely difficult to be machined using conventional cutting processes because of their very high hardness and brittleness. In this work, an analysis of the process performances and the surface quality characteristics are carried out to evaluate the machinability and the stability of micro-EDM process on these relatively new materials. In particular, Zirconium Boride (ZrB2) with different volume fractions of non-reactive additives (in this case SiC) is used as the workpiece and a simple micro-feature is chosen as reference shape for the micro-EDM milling process. The process performance is evaluated by collecting machining time, tool wear and material removal volume. The surface quality was evaluated by a 3D reconstruction of the micro-features machined and an elaboration by a scanning probe image processor software. The results show high stability and repeatability of the process for the evaluated additive fractions. In particular, the workpiece characterized by the 20% vol. of additive showed the best results in terms of surface quality and precision of the geometry after machining.