Modelling the Influence of Stretched Molding Foil on the Overall Dimensions of Molded Packages

In this paper, we describe a method to predict the thickness of a stretched molding foil inside a mold. Because this foil will influence the overall dimensions of packages after molding, it is necessary to predict its thickness in advance when it is deployed in the cavity. In this way, dimensional corrections of the mold in the design phase can be made to meet the tight dimensional tolerances. Furthermore, the foil is not allowed to tear during molding. To assess the change of foil-thickness and the risk to tearing, models are developed. Firstly, a simplified foil stretching model is described for calculating the foil thickness in a two-dimensional rectangular geometry. Comparisons with measurements are made to prove this model. Secondly, a three-dimensional FEM simulation with the hyper elastic Odgen model on a complex geometry is performed and compared with measurements.