Compression molding of sheet molding compound in molds with or without substructure

An experimental and numerical analysis of compression molding was carried out to investigate flow of sheet molding compound (SMC) at various processing conditions in the molds with and without substructure. A squeeze flow rheometer was applied to measure the flow resistance under compression for a rheological study. It was found from this study that the SMC under compression can be characterized by three flow stages. By using a power law model combined with a yield stress, the flow behavior of SMC was modelled reasonably well. The experimental study on the nonisothermal compression molding was carried out on two instrumented molds, one flat mold and the other with a substructure like 'T' shape. For the numerical analysis, a flow formulation has been adopted and a finite element code ALPID was used for simulation by providing the experimentally determined SMC property. The flow front shape and pressure change during compression compared well with experimental results.