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Micro-cutting of a MMC-composite for enhanced injection moulds

: Uhlmann, E.; Polte, M.; Hein, C.; Polte, J.; Jahnke, C.

Leach, R. ; European Society for Precision Engineering and Nanotechnology -EUSPEN-:
19th International Conference of the European Society for Precision Engineering and Nanotechnology 2019. Proceedings : June 3rd-7th June 2019, Bilbao, ES
Bedford: Euspen, 2019
ISBN: 978-0-9957751-4-5
European Society for Precision Engineering and Nanotechnology (EUSPEN International Conference) <19, 2019, Bilbao>
Fraunhofer IPK ()

Tools for micro-injection moulding are currently made of hardened steel. These tools are exposed to high local loads, which significantly reduce the injection moulding tool life time tT. Furthermore, the occurring wear of the milling tool during machining of hardened steel leads to reduced surface roughness Ra and geometrical accuracy GF. Copper and aluminium alloys as mould materials provide an alternative to hardened steel with advantages regarding material removal rate QW and wear of the milling tool, but with a significantly reduced life time of the injection moulding tool tT. Until now, the combination of a good machinability and high wear resistance cannot be achieved. The approach, presented in this paper consists of an easy to machine material and the development of a wear resistant metal-matrix-composite (MMC) material layer with a hardness of up to 3,000 HV. Therefore, the pre-machined test specimens made of aluminium-bronze are coated by laser dispersing with wolfram-carbide-particles W2C-WC. Furthermore, for the finishing machining of the coated moulds, a cutting technology for the machining of W2C-WC-particles was developed. The verification of the developed technology was performed with an injection moulding process based on carbon-fibre reinforced thermoplastic material. By means of documented machining efforts, the quality indicators geometrical accuracy GF and surface roughness Ra as well as occurring tool wear, the feasibility of the developed technology was demonstrated.