Flow behavior of stampable sheet with a rib part

Abstract The effect of die design on the flow characteristics of compression molded three‐layer long glass fiber reinforced polypropylene composite, known as “stampable sheet,” was investigated. The flow behavior of each layer was observed by optical and soft X‐ray photographs. The fiber flow length into the rib part was measured by an image processing system. The results showed that during compression resin exudation occurred and that this depended on the die's rib width. Thus, the larger the rib width, the lower the amount of resin exuded. Resin exudation was found to occur earlier in a die with zero fillet radius. The fiber flow length into the rib part was enhanced by using a die with a large fillet radius. The results were confirmed by a short‐shot molding process. In this process, the stamping operation was stopped short of making a complete part. A finite element method was used to study the flow process. The results agree with the experimental results confirmed by short‐shot molding.