Mould design Improving cooling inserts with evolutionary theory
In a project to run until the end of next year, algorithms taken from nature may provide the key to designing thermal channels in plastic injection moulds, according to researchers Christian Hopmann and Philipp Nikoleizig.
Injection moulding is one of the most-widespread processes for making plastic products. Within this process, the mould is accountable for several complex functions during the moulding cycle, which is mainly characterised by the cooling of the melt, the freezing and the demoulding point. Heat removal is carried out to a large extent via an integrated tempering system inside the mould, with other heat transport mechanisms like convective flux or heat conduction playing minor roles. An economic process can particularly be achieved through fast heat removal. In addition, the cooling of the melt also influences the attributes of the part such as the surface quality or the warpage. The latter can result from unbalanced cooling and thereby a different shrinkage of individual sections of the part.
Tempering channels are usually created with boreholes inside the mould. Their course is then defined via stoppers at required positions. However, additional elements can allow heat removal in hard-to-access areas, for example, ascending pipes, high conductivity brads or other elements. Innovative approaches propose additive manufacturing of the mould insert. The procedure creates a layer-by-layer build-up of the insert, which allows for almost any shape and course of the tempering channel.