Daniel F. Walczyk PhD, PE, Professor and Center Director, Rensselaer Polytechnic Institute
Daniel A. Kaczmarek, Graduate Student, Rensselaer Polytechnic Institute
The goal of this research is to develop an open-source deposition head for impregnating continuous dry fiber reinforcement tows in-situ with a thermoplastic matrix for non-planar additive manufacturing and other automated composites manufacturing processes (e.g., mandrel-wrapping, automated fiber placement). The design consists of a heated plunger to meter molten plastic (extruder envisioned for future work) into an impregnation chamber, where fiber passes and is impregnated. It is unlike the systems on the market (MarkForged) which uses pre-impregnated fiber but is similar to systems in development (Arevo Labs, Orbital Composites) in that dry fiber and pellet thermoplastics are used. Based on experiments and simulation, findings determined that the rate and quality of fiber impregnation depends on the resin viscosity and chamber pressure. Using the deposition head, test samples of carbon fiber (3K, 6K) are infused with thermoplastics resins (PETG, Nylon, Polycarbonate) at various pressures, temperatures and fiber feed rates. To assess the quality of impregnation for samples, the percent impregnation, is determined using microscopy. Finally, samples are tested in three-point bending, to observe stiffness and fracture behavior of the impregnated tows. Experimental results and lessons learned will be used for a 2nd generation deposition head and actual additive manufacturing builds.