Simulation of mold filling in simultaneous resin injection/compression molding

In the present article, an open gap is present between the fibrous reinforcements and the upper mold during the filling stage of resin injection/compression molding (I/CM). Thus resin can quickly fill up the gap. After that, the mold platens are brought together and drive the resin, through the preform. The resin motion in the gap is simplified using the Hele-Shaw flow model, while Darcy's law is used to calculate the flow fields in the fiber mats. The numerical simulation is based on the body-fitted finite element method (FEM). Results show that the resin injection time is short and most filling time is elevated to the closing of the cavity in the simultaneous I/CM filling process. Small gap size and high compression speed can be used to achieve the minimum mold filling time. However, the improper process parameters can cause the incomplete filling or reversed flow at the gate. In order to avoid the above conditions, the restrictive conditions of simultaneous I/CM are also discussed. The simultaneous I/CM can reduce either the mold filling time or injection pressure significantly compared to resin transfer molding (RTM).