Phenomenological analysis of the technological limitations in sinking EDM with low discharge energy and graphite tool electrodes

• Applicant: Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Joining and Separation Technology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 496148524

The selection of an appropriate tool electrode material for die-sinking electrical discharge machining (EDM) is connected to different boundary conditions. An economic production requires high material removal rate with minimal relative tool wear at the same time. Thus, the physical removal principle results in a need for a high electrical conductivity, thermal conductivity, specific heat capacity and a high melting point to ensure the best possible discharge characteristics and heat dissipation at the tool electrode. Manufacturing of complex and fine structures like thin bars with low wall thicknesses requires a sufficient mechanical strength of the material. Graphite is therefore used as a tool electrode material for electrical discharge machining, where this group of materials enables almost wear-free machining at high removal rates. In the area of EDM finishing and fine-finishing, graphite, like other materials, shows a significant increase in relative tool wear. This increase is particularly high for graphite, which hardly enables the economical use of graphite tool electrodes in EDM finishing processes. In preliminary tests, however, an opposite wear behaviour could be observed, which is not described by the state of the art.The aim of the research project is therefore the description of wear phenomena and the validation of different graphites as material for tool electrodes in EDM finishing and the identification of suitable process parameters for the finishing and polishing of steel. In this context the minimal achievable roughness parameters for the application of graphite will be determined as well. Through the scientific analysis of the composition of graphite materials and the fundamental investigation of the EDM process behaviour, far-reaching findings in the field of production technology can be obtained. These findings make it possible to increase productivity in the application area of EDM, as the knowledge gained enables the advantages of graphite materials to be optimally exploited in EDM finishing processes.

• DFG Programme: Research Grants