Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Characterization and investigation of binderless nanopolycrystalline diamond turning tools for precision machining
    ( 2022)
    Uhlmann, Eckart
    ;
    Sturm, Heinz
    ;
    Polte, Mitchel
    ;
    Hocke, T.
    ;
    Polte, C.
    ;
    Polte, Julian
    Cemented carbide is used in a wide range of industrial applications as a wear-resistant material, e.g. in mould making and forming industry. At state of the art, the machining of cemented carbide is severely limited because of the hardness, high strength and the resulting wear resistance of the material. Due to the brittle-hard character cemented carbide materials suffer from surface cracks during the machining. The brittle-hard character and the related phenomena result in high tool wear. A promising approach for the machining of cemented carbide is the use of the novel cutting material binderless nanopolycrystalline diamond (NPD) with a dedicated cutting edge design. Within this work, laser machined tools with a corner radius of rε = 400 µm are fully characterized, investigated by Raman spectroscopy regarding the condition of the diamond and applied for first cutting experiments. Cutting investigations were carried out using specimens with a tungsten carbide content of cC = 88 %, a cobalt content of cCo= 12 % and a grain size of dg= 0.5 µm. Prior to these investigations, the condition of the diamonds and possible changes due to the lasered cutting edges were examined by Raman spectroscopy. During the cutting investigations, the brittle-ductile transition as well as the minimum chip thickness were identified by scratching tests. It could be shown that a hydrostatic stress state can be used to achieve ductile chip formation using cemented carbide as workpiece material.