| Abstract: | The use of prototype moulds made with rapid tooling (RT)‐techniques offers the possibility to manufacture prototypes in the series process. Although the series material is used during injection moulding, the properties of the prototype are not identical with the product because of the varying surface qualities of the RT‐moulds and the different thermal conditions in the process. In this work, different RT‐techniques (resin casting, metal spraying, selective laser sintering, investment casting and keltooling) are investigated according to the morphological as well as the mechanical properties of injection‐moulded prototypes. The specimen are compared with parts that were injection‐moulded in a steel mould to realise a comparison between prototype and product. The thermal diffusivity of the analysed RT‐mould materials differs from one tenth of the value of steel up to seven times higher compared to steel. This leads to a different morphology of the prototype concerning the boundary layers and the spherulite size. A good heat conducting material (e. g. aluminium investment casting mould) causes thick boundary layers and small spherulites. In contrast, a rather insulating mould material (e. g. resin casting mould) results in thin boundary layers and large spherulites. The investigations show that the effect of a good heat conducting material can be achieved by using a lower mould temperature for badly conducting materials in the same way. The yield stress of the prototypes differs up to 20% from the mechanical properties of the product and is influenced by the spherulite size and the mould's surface quality. The prototype, moulded in a keltool mould, shows the best resemblance with the product. |
