Basic research concerning Electrical Discharge Machining with additive manufactured tool electrodes
Final Report Abstract
This research project focused on improving the sinking EDM (S-EDM) process using additively manufactured tool electrodes made of tungsten carbide-cobalt (WC-Co). Therefore, the production of complex electrode geometries with integrated internal flushing channels and their effects on the S-EDM process were investigated as well as suitable additive manufacturing parameters for manufacturing of dedicated samples and tool electrodes were evaluated. Furthermore, the effects of additively manufactured samples with different relative densities ρrel and cobalt contents GCo on the S-EDM process were investigated. The goal was to generate workpiece surfaces with qualities of grade 30 according to VDI 3400 [VDI3400], corresponding to a surface roughness of Ra = 3.15 μm. Within the research project, suitable additive manufacturing parameters were identified to manufacture samples with a relative density of ρrel > 93 %. The highest values in both relative density ρrel and cobalt content GCo were achieved with energy densities of Ev = 300 J/mm3 and Ev = 500 J/mm3. Thereby, the continuous chessboard scan strategy proved most promising. Suitable processing parameters for the S-EDM process were found to generate workpiece surfaces with a surface roughness of Ra = 3.2 μm. The evaluation of the S-EDM experiments showed that both the relative density ρrel and the cobalt content GCo positively influence the material removal rate V̇W. Additively manufactured samples with an energy density of Ev = 300 J/mm3 showed higher cobalt contents GCo. However, the samples manufactured with a higher energy density of Ev = 500 J/mm3 showed significantly better removal rates V̇W, attributed to their higher relative densities ρrel. Numerical simulations were further utilised to identify optimised flushing conditions. Round, square and cloverleaf-shaped channel structures were investigated for various cross-sectional areas Aq and flushing pressures Pin. The evaluation indicated the best conditions in the frontal gap for the examined cavities with a square flushing channel cross-section. Considering all results and insights, tool electrodes with a frontal surface of Af = 2 mm x 10 mm and an integrated flushing channel could be successfully manufactured. For the first time, additive manufactured WC-Co tool electrodes with high aspect ratios Θ were manufactured. At the end of the project, the potential of freeform shaping could be shown for S EDM-processes.
Publications
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Investigation of additive manufactured tungsten carbide-cobalt tool electrodes for sinking EDM. Proceedings of 37th Annual Meeting of American Society for Precision Engineering (2022), S. 323 – 328, ISBN 978-1-887706-56-8.
Uhlmann E.; Polte M.; Hörl R.; Braun T & Bolz R.
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Increasing the Relative Density of Additively Manufactured Tungsten Carbide-Cobalt Tool Electrodes for EDM. Proceedings of 38th Annual Meeting of American Society for Precision Engineering (2023), S. 310 – 313, ISBN 978-1- 887706-59-9.
Uhlmann, E.; Polte, M.; Hörl, R.; Reimann, R.; Braun, T. & Hocke, T.
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Neuschäfer, R.: Additiv gefertigte WC-Co- Werkzeugelektroden für das funkenerosive Senken. Maschinenmarkt, Jahrgang 129, Ausgabe 3 (2023), S. 48 – 51.
Uhlmann, E.; Polte, M.; Hörl, R.; Bolz, R. & Braun, T.
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Parameter Optimization of Additive Manufacturing Process LPBF Using an Evolution Strategy Algorithm Applied on the Material Tungsten Carbide Cobalt WC – Co 83/17. Advances in Material Science Research. Volume 64 (2023), S. 245 – 255, ISBN 979-8-88697-935-0.
Uhlmann, E.; Polte, J.; Cherres, J.D.; Kochan, J. & Alum, A.S.
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Spark erosion with additively manufactured WC-Co electrodes. ETMM, Volume 25, 2 (2023), S. 36 – 37.
Uhlmann, E.; Polte, M.; Hörl, R.; Bolz, R. & Braun, T.
