Technological and Economic Investigations on the Application of Metal Infiltrated Graphite Electrodes for the Sinking EDM of Cemented Carbides

摘要

Cemented carbides are a substantial tool material in various production areas, but to date these are almost impossible to machine by conventional manufacturing processes. Since electric discharge machining (EDM) is a process that benefits from a nearly force free thermal material removal principle, it is distinguished for the machining of cemented carbides. State-of-the-art sinking EDM (SEDM) technology uses tungsten copper alloys as tool electrode materials for this application, but shortage of resources in tungsten production leads to rising prices and increasing manufacturing costs. This leads to great interest for advanced SEDM processes to manufacture cemented carbides. One of the most used material for tool electrodes in standard SEDM applications is conventional graphite, however, the process is far from being economically efficient using graphite compared to using tungsten copper alloys for the machining of cemented carbides. A promising alternative is metal infiltrated graphite, since it shall inherit benefits from both materials without being as cost-intensive as tungsten copper alloys. This research is both about technological and economic investigations using metal infiltrated graphite as tool electrodes for the SEDM processing of cemented carbides. A set of technological parameters is identified that results in higher material removal rates using the alternative material. Compared to the state-of-the-art the relative tool wear is still higher, but the alternative material can be applied with more economic efficiency.