Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Additive manufacturing of precision cemented carbide parts
    ( 2021)
    Polte, Julian
    ;
    Polte, Mitchel
    ;
    Lahoda, Christian
    ;
    Hocke, Toni
    ;
    Uhlmann, Eckart
    Cemented carbide parts are commonly used as wear resistance components in a broad range of industry, e.g. for forming, mould making and matrices. At state of the art the machining of precision cemented carbide components by milling is strongly limited due to excessive tool wear and long machining times. Promising approaches for precision machining of cemented carbide components are dedicated cutting tool coatings, new cutting materials like binderless polycrystalline diamond and ultrasonic-assisted machining. Nevertheless, for all these approaches the components need to be machined of monolithic materials. The new approach addresses an innovative manufacturing process chain composed of near net shape Additive Manufacturing followed by a precision finishing process. Within this investigations for the manufacturing of precision cemented carbide parts, cemented carbide with a cobalt content of 17 % and a grain size in a range of 23 µm ⤠gs ⤠40 µm were used. As Addit ive Manufacturing technology laser powder bed fusion was used. Diamond slide burnishing and immersed tumbling were investigated as finishing technologies. Based on the investigations, a dedicated process chain for the manufacturing of precision cemented carbide parts could be realised. The findings show that the developed process chain composed of near net shape Additive Manufacturing and the finishing process diamond slide burnishing enables the manufacturing of precision cemented carbide parts with a geometrical accuracy of ag ⤠10 µm. Due to the finishing process the initial surface roughness after Additive Manufacturing could reduce by Ra = 89 %.
  • Publication
    Effects on part density for a highly productive manufacturing of WC-Co via laser powder bed fusion
    ( 2021)
    Polte, Julian
    ;
    Neuwald, Tobias
    ;
    Gordei, Anzhelika
    ;
    Kersting, Robert
    ;
    Uhlmann, Eckart
    The additive manufacturing of parts made from difficult-to-weld materials through the usage of preheating temperatures of up to Î0 ⤠500 °C is enabled by newest L-PBF machine tools, such as the RenAM 500Q HT from the company RENISHAW PLC, Wottun-under-Edge, UK. This work aims to delevop processing parameters for the dense and crack-free manufacturing of tungsten-carbide cobalt (WC-Co) via this off-the-shelf machine tool. Therefore the laserpower and scanning speed were varied between 80 W ⤠PL ⤠350 W and 140 mm/s ⤠vS ⤠650 mm/s respectively. Furthermore the influence of a continuous and pulsed laser mode was analysed. A focus was set on the identification of parameters that enable a highly productive manufacturing while maintaining a high part density. A parameter set for relative density rel. > 94 % and a buildup rate v = 0.59 mm3/s was developed.
  • Publication
    Heat treatment of SLM-LMD hybrid components
    ( 2019)
    Uhlmann, Eckart
    ;
    Düchting, Jan
    ;
    Petrat, Torsten
    ;
    Graf, Benjamin
    ;
    Rethmeier, Michael
    Additive manufacturing is no longer just used for the production of prototypes but already found its way into the industrial production. However, the fabrication of massive metallic parts with high geometrical complexity is still too time-consuming to be economically viable. The combination of the powder bed-based selective laser melting process (SLM), known for its geometrical freedom and accuracy, and the nozzle-based laser metal deposition process (LMD), known for its high build-up rates, has great potential to reduce the process duration. For the industrial application of the SLM-LMD hybrid process chain it is necessary to investigate the interaction of the processes and its effect on the material properties to guarantee part quality and prevent component failure. Therefore, hybrid components are manufactured and examined before and after the heat treatment regarding the microstructure and the hardness in the SLM-LMD transition zone. The experiments are conducted using the nickel-based alloy Inconel 718.