This presentation was made at the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

In order to explore methods to improve the quality of thermoplastic overmoulded parts, a parametric study has been performed to investigate a thermoplastic composite overmoulding process, in which a short glass fibre reinforced polyamide 6 compound is injection moulded onto the surface of a polyamide 6 based glass twill fabric reinforced organosheet. Three injection overmoulding parameters: melt temperature, insert temperature, and injection speed, were studied using an experimentally validated injection moulding process model. The effects of the parameters on the warpage and the interfacial degree of healing of the overmoulded thermoplastic composite part have been revealed.



It has been found that the melt temperature predominantly controls the magnitude of warpage and the degree of healing, both of which increase with melt temperature. Increases to the injection speed are found to promote the degree of healing without introducing extra warpage, providing a novel method to improve the part quality when melt temperature cannot be increased further. A significant variation of the degree of healing from the sprue to the end of the rib has been found, which can be reduced by increasing the injection speed, or by adjusting sprue position to maximise structural strength. In contrast, the influence of the insert temperature on the resulting part strength have been limited, which indicates the insensitivity of the part quality to small insert temperature variations, while stringent control measures must be applied to reduce variation in melt temperature and injection speed.