InImpact: The Journal of Innovation Impact

Publisher Future Technology Press
Vol. 7 No. 2 KES Transactions on SDM I - Sustainable Design and Manufacturing 2014
Volume Editors KES International
Journal ISSN 2051-6002
Article TitleAn exploration of core misalignment, shifting and deflection phenomena through thickness measurements on thin-walled injection moulded bins
Primary AuthorMarton Huszar, College of Engineering, Swansea University
Other Author(s) Fawzi Belblidia; Cris Arnold; David Bould; Johann Sienz
Pages 108 - 119
Article ID sdm14-052
Publication Date 01-May-16
AbstractInjection moulding has been a widely adopted technique to produce plastic components. Hollow parts, such as bins and tubes require cores mounted in the injection mould to be able to produce the desired geometry. Unbalanced injection pressure imposed on the core may deflect it causing spatial deviation between the core/cavity interfaces, resulting in part thickness deviation. This study investigated the part-thickness evolution of a rectangular closed-end plastic container moulded with a single cantilever core mounted on the moving plate of the injection mould. The evaluation of part-thickness variation caused by unbalanced injection pressure can be used to improve the injection moulding process, ensuring sustainable manufacturing. Using optimised process settings can reduce raw material usage, energy consumption and production waste. Cavity filling simulations and experimental validation using polypropylene grades with different melt flow indices (MFI) were performed. Hydraulic pressure values were linked to wall-thickness measurements taken on the cross-sectioned moulded parts. Thickness data indicated the existence of core misalignment (core not initially set up symmetrically within the cavity) as a root cause of core shifting and deflection phenomena. It is concluded that the magnitude of core deflection could be controlled by altering the hydraulic pressure, however core shifting could not be. The flow front advancement of a short-shot sample confirmed the coupled effect of core shifting and deflection.
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