A Way Towards Optimization of Injection Molding

Abstract

Injection molding of thermoplastic is a complex process essentially because of the physical properties of the polymers, the processing conditions and the mold geometry. One key issue is to find the optimal location of the injection point(s) so that to minimize the final pressure required to fill the mould. This is usually achieved by using commercial computer codes, which are time consuming. Our approach, which is not classical, consists in introducing several “geometrical tools” of image analysis such as optimal centering and skeleton transformation, to characterize the shape properties of the flow filling the mould cavity. A direct correlation between the geometrical parameters associated to image analysis and the results based on the classical Hele-Shaw model is obtained for several molds. Furthermore, the physical problem is not completely taken into account by the mathematical formulation based on the considered geometrical tools. It is the reason why a new formulation is proposed, taking the governing equations of the model into consideration. As the physical problem is of an elliptic form, its energetic formulation can be used to answer our problematic. In son doing, for a given fluid, the optimal position of the injection points can be found by writing a quadratic optimization problem. In this paper, we present the first results devoted to the optimization of the filling phase.