Direct generation of 3D structures by laser polymer deposition

Additive manufacturing with polymers is typically performed using techniques such as stereolithography, selective laser sintering (SLS), or fused deposition modeling. SLS of unmodified powders with CO2 lasers represents the state of the art in powder-based polymer additive manufacturing. In the presented work, thermoplastic polyurethane was successfully processed for the first time with a powder feed technique, which is similar to the well-known laser metal deposition. The powder material was doped with carbon black in order to increase the absorptivity of the powder material for laser radiation in the near-infrared range. Various geometries were produced using a standard laser cladding setup with a modified powder feeding system and an Nd:YAG laser. The powder material and the generated structures were characterized by scanning electron microscopy. Structural properties, e.g., porosity, were controlled by different fabrication strategies and process parameters. Furthermore, hybrid structures consisting of metal and polymer parts were successfully produced in the same experimental setup by using two different powder feeders.