Fiber Orientation State Depending on the Injection Mold Gate Variations during FRP Injection Molding

Abstract

Because of orientation and separation, injection molded products are heterogeneous and anisotropic. These heterogeneousness and anisotropy have a vast influence on mechanical properties of molding material and product characteristics. It is well known that fiber orientation state in fiber-reinforced polymeric composite has a profound effect on dynamic qualities like intensity, rigidity, and etc. To measure the fiber orientation of injection molded product's weld part, we first X-rayed moldings and recognized this photo by using an image scanner. Then, image processing method, which uses intensity difference in measuring fiber orientation state, is applied. Through these procedures, we can analyze the influence of molding's fiber orientation state according to mold gate changes. Fiber orientation is related mainly with the mold gate positions than with fiber content or mold temperature. When the distance from the gate increases, by matrix and reinforcement's flow speed differences, fiber orientation occurred. As diversion flow occurred at the end of fluid flow, fiber oriented at a right angle to the flow, and this is the same effect of weld line formation.