Basic research on μEDM milling with tool electrodes made of boron-doped diamond

• Applicant: Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 521489341

Electrical discharge machining (EDM) is used as a production process for the machining of electrically conductive materials, regardless of their hardness H and strength E. EDM with ultra-finely structured tool electrodes is called micro-sinking EDM and is mainly used for the manufacturing of micro-moulding tools. However, in micro-sinking EDM the tool electrode is subject to a significantly higher relative wear theta compared to macro-sinking EDM. Due to the small working gap s, the flushing conditions also deteriorate, leading to an increasing number of short-circuit and arc discharges. In addition, the ultra-fine structures of the tool electrodes can dissipate the process heat Q only poorly. In order to guarantee the required shape accuracy GF, several tool electrodes have to be used during micro-sinking EDM to produce a cavity. Micro EDM with a rotating tool electrode, known as micro EDM milling, is an alternative. With micro EDM milling three-dimensional structures can be produced, similar to frontal circumferential milling. Micro EDM milling has the advantage that no finely structured tool electrodes are required, as in case of micro-sinking EDM. In addition, the relative movement of the tool electrode and the "open" contour provide significantly better flushing conditions. The main factor influencing the achievable dimensional accuracy GM and shape accuracy GF is the relative wear theta of the tool electrodes. The main object of research in this field is therefore the development of suitable wear compensation strategies. Tool electrode materials with a high melting temperature TS are predominantly used in wear-intensive micro EDM. These mainly include tungsten-copper materials and hard metals made of tungsten carbide-cobalt. Based on the preliminary investigations, it was also possible to identify a high potential of electrically conductive, boron-doped diamonds as wear-resistant tool electrodes in micro EDM milling. However, there are no known publications or scientific papers dealing with the research or application of electrically conductive boron-doped diamonds for micro EDM milling. Once the proposed research project has been completed, basic scientific knowledge and usable technologies will be available that will give Germany an advance in the global scientific and economic environment.

• DFG Programme: Research Grants