Thermal management of moulds and dies : a contribution to improved design and manufacture of tooling for injection moulding

[摘要] ENGLISH ABSTRACT: Injection moulding of polymer components is subject to ever increasing demands for improvedpart quality and production rate. It is widely recognised that the mould cooling strategy employedis crucial to achieving these goals. A brief overview of injection moulding units and different typesof injection moulds is given.The modern Additive Manufacturing (AM) technology for processing metal powders such asDirect Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) offers almost fullfreedom to the mould designer. Some of these modern manufacturing methods based on metalpowders, which are able to produce complex cooling channels are analysed.A drastic change has entered the mould design domain - shifting the paradigm from design formanufacture to manufacture for design. In combination with suitable AM methods the concept ofsurface cooling moulds can now be efficiently implemented.This study presents a new approach of predicting the minimum cooling time required for theproduced part. Different cooling layouts are analysed taking the heat transfer into consideration.The lumped heat capacity method is implemented in this research in order to determine theminimum cooling cycle time required.A new approach was developed to determine the most suitable cooling layout configuration, suchas conventional cooling, conformal cooling or surface cooling, required for a moulded part basedon its characteristics such as shape complexity, space available for the cooling layout, partquality requirements, production volume, and product life cycle.A mould cooling design process including simulation, reverse engineering and manufacturing ofthe mould insert was implemented in this study.In order to validate the generic model developed during the course of this research comparativeexperiments were carried out to determine the difference in performance of injection mouldingusing conventional or surface cooling methods. The experimental results showed a significantimprovement in part quality produced with reduced cycle times using the surface cooling method.

[发布机构] Stellenbosch University