A Comparison between Additively and Conventionally Manufactured Injection Moulding Inserts

The cooling time in injection moulding can constitute up to 70% of the cycle time. With the additive manufacturing technology there is a new method for designing and optimizing cooling channels available. With this method it is possible to manufacture conformal cooling channels randomly orientated inside injection moulds. This enables the possibility to design more efficient cooling and more even heat dissipations, which results in a reduction of thermal stresses and higher accuracies of injection moulding parts. Against this background, the central question that motivates this paper is: What are the main differences between additive manufactured conformal cooling channels and conventional manufactured cooling channels? To directly compare both manufacturing strategies a test injection mould was manufactured which was designed in a way that both a conventional and an additive manufactured insert can be operated simultaneously. In this context one section of the injection mould was manufactured by using the selective laser melting technology. The second section of the mould was manufactured conventionally by milling. This opens the possibility to compare both manufacturing technologies within the same injection moulding cycle. After the additive and the conventional inserts of the mould were manufactured several injection moulding experiments were accomplished. For evaluating the heat distribution on the injection moulding part thermographic measurement methods were used. Furthermore the effects of mould temperature, coolant volume flow and cooling time on the part surface temperature were examined.