A Numerical Study of Filling Process in Resin Injection/Compression Molding

Resin injection/compression molding (RI/CM) is a variant of the resin transfer molding (RTM) process to produce advanced composites. In the present model, a gap is present between the fibrous preform and the upper mold during the RI/CM filling process. The gap results in a preferential flow path during resin injection. After enough resin is injected, the closing action of the mold initiates and forces the resin in the gap to penetrate into the fibrous preform. The resin flow in the gap is simplified by the Hele-Shaw flow model, while Darcy's law is used to calculate the flow field in the fibrous preform. Two modes of compression phase, either constant speed or clamping force, are discussed. Numerical results show that the process of resin penetrating into fibrous preform is a key factor in the RI/CM cyclic period and the clamping force. By comparing two compression modes, the compression time reduction can be made by applying the full capacity of the clamping force from the initiation of compression for the version of constant force compression. As compared to RTM, the RI/CM process can significantly reduce the mold filling time using a low injection/compression pressure.