Analysis of function-oriented surfaces of injection moulding cavities manufactured by electrical discharge machining

• Applicants: Professor Dr.-Ing. Thomas Bergs; Professor Dr.-Ing. Christian Hopmann
• Subject Area: Plastics Engineering
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 447707042

The flow path lengths previously achievable in injection moulding often represent a limitation both for thin-walled packaging applications and for technical components with long flow paths. Previous studies have shown qualitatively that a microstructured mould surface can have a positive influence on the flow and cooling behaviour of the plastic melt in the cavity. This can be attributed to micro air cushions between the plastic melt and the mould, which influence the heat transfer. The result is a lower required injection pressure or the realisation of longer flow paths. In addition, faster filling times at constant injection pressures can reduce the cycle time of the injection moulding process. The influence of surface roughness on the flow behaviour and the heat transfer coefficient in injection moulding, which was researched in the first funding period, is to be further investigated and the description of the influence further developed. The aim of the IKV is to better predict the surface moulding and thus the heat transfer as a function of the material, the flow path and the local melt properties such as pressure and temperature. These findings can in turn be used to improve the prediction of the flow behaviour of plastics in structured injection moulds by means of simulation. In addition, the influence of the surface structure on demouldability and demoulding forces in the injection mould is to be investigated in order to analyse the applicability of surface structuring technology. The central aim of the WZL is to develop a model for function-orientated production using EDM. The first step is to analyse the influence of the unloading parameters on the surface topography. A subsequent correlation analysis between the relevant functional properties and the surface parameters will ultimately enable the development of a regression model. The model developed as part of the proposed research project should ultimately be able to determine process parameters that enable the creation of an optimum cavity surface for the injection moulding process.

• DFG Programme: Research Grants