Additive manufacturing based on screw extrusion: machines, material and applications in the automotive industry

Abstract

For automotive applications the major limitations of established additive manufacturing processes (e.g. FDM, SLS, SLA etc.) are known to be either part size, material properties, costs for material/machine, or production speed. Screw Extrusion Additive Manufacturing (SEAM) can overcome these limitations and has the potential to be economically competitive compared to the injection-molding process for small and medium part quantities up to 100,000 parts over lifetime. Using screw extrusion for the plastification of series-production-qualified injection-molding granules and an automated 6-axis robot system, the SEAM process is able to produce geometrically complex, large-scale parts from thermoplastic polymers. Due to the diversity of material on the market, including granules with a high percentage of fiber reinforcement, the material costs for the additive manufacturing of high-performance parts can be drastically reduced. The smart design of the SEAM machine additionally enables the option for hybrid manufacturing (additive and subtractive manufacturing), since the extruder mounted on the robot can be exchanged for a milling or drilling unit. If, in addition to the high material throughput of SEAM, the design of the parts corresponds to the design guidelines of the SEAM process, fast production cycles can be achieved to further obtain cost savings. For the automotive industry the SEAM process can be used to produce structural or decorative carrier parts for interior and exterior applications in small and medium quantities and limited special editions. Furthermore, large-format parts manufactured by this process can support series development during the prototyping phase. In the following article the characteristics of the SEAM process and respective applications are described in more detail. Additionally, future must-have developments will be explained below highlighted with CAD/CAM demands on the market.