Abstract
Cold forging enables mass production of steel based components. High loads within cold forging presuppose high loadable tool materials. This is why apart from tool steels cemented carbides are mainly used as tool materials. Due to brittleness of these materials, fatigue is one of the major limits of tool life. Tool manufacturing requires a combination of hard machining and subsequent machining steps. For hard machining of complex tool geometries electrical discharge machining (EDM) represents the industrial standard. The thermal influenced surface layer has to be removed by post and fine machining steps. The resulting surface integrity has a major influence on the internal strength of a tool. Correlations between tool manufacturing, surface properties and tool behavior will gain knowledge for an optimized tool production. In this context, scope of the present paper are the investigation and description of the interactions between tool manufacturing and resulting surface properties for tools made of cemented carbide and tool steel. Within the article, the surface properties caused by a conventional process chain consisting of EDM and polishing are quantified. In addition, these results are compared to an adapted process chain with an integrated peening process. The results reveal that the conventional and the adapted process chain lead to similar surface topographies and roughness values. However, the integration of a peening process shifts the residual stress level towards higher compressive stresses.
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Acknowledgments
The authors would like to thank the Bavarian Research Foundation for their financial support of the research project BFS 1001–11. Furthermore, the authors acknowledge the tool manufacturer FRANK Formenbau for machining the specimens as well as the companies Richard Bergner and ThyssenKrupp Presta for scientifically discussion.
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Andreas, K., Merklein, M. Improvement of surface integrity of cold forging tools by adaption of tool making process. Prod. Eng. Res. Devel. 8, 131–141 (2014). https://doi.org/10.1007/s11740-013-0522-y
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DOI: https://doi.org/10.1007/s11740-013-0522-y