Spark Erosion of Hard Metals for Precision Glass Moulding

Direct moulding of glass optics helps to significantly lower production costs and achieve market dominance. However, due the specific physical properties of the hard metals used in precision glass moulding, these materials can be effectively machined only by few processes. Spark erosion (EDM) process shows advantages over other processes in generating specific shapes on conductive super-hard materials, and it is considered as a rough-shaping process for making a precision mold in the process chain of direct glass moulding. This paper presents the preliminary research work on EDM milling of small features conducted on two machines, namely CHARMILLES ROBOMILL and SARIX SX-100-HPM micro-EDM machine. The surface quality, achievable figure accuracy and effects of machining parameters are investigated.