Modeling of sheet molding compound compression molding under non-isothermal conditions

Abstract

Sheet molding compound compression molding is a complicated manufacturing process. The main goal of the present research is to determine the required molding axial compression stress of the sheet molding compound in different conditions, using minimum experimental data. In the present research, the effective process parameters on molding forces such as the initial sheet molding compound temperature, the axial punch velocity, and the temperature of the mold surface are studied. It is shown that considering the charge under isothermal condition, especially in the filling stage is not a reasonable assumption. Thus, the applied rheological model of sheet molding compound flow is modified by accounting the thermal variations during the filling stage. The power law model is implemented to propose a novel model for prediction of the hydrodynamic friction as the dominant friction of the sheet molding compound compression molding process. Finally, a model has been developed to predict the molding axial compression stress under non-isothermal conditions. The proposed model is simple and general and does not need any extra experimental parameters. The results obtained by the model are in a very good agreement with the available experimental data.