Direct Processing of Continuous Fibers onto Injection Molding Machines

A new injection molding process "DIF" (Direct Incorporation of Con tinuous Fibers) is proposed whereby roving strands are directly incorporated into the polymer melt by using a reciprocating-screw-plasticating unit. The DIF-technology offers the possibility to substitute the relatively expensive pultrusion process which is used to produce long fiber pellets. Furthermore it can be used as a fast and flexible R&D tool. In order to improve fiber dispersion with minimum fiber breakage a new mixing non-return-valve" LFMR" ( Long Fiber Mixing Ring) was developed based on the " Twente Mixing Ring." Its mixing capacity and influence on processing charactenstics, fiber breakage and property profile of the injection molded parts is examined and compared to a general purpose non-return-valve of the ring type. The results of fundamental mechanical and physical property investigations are presented including dispersion of fiber clusters and bundles, fiber length distribution and fiber orientation.