3D printing of metal parts using a highly-filled thermoplastic filament

Purpose This study aims to develop a highly loaded filament with spherical metallic particles for fused filament fabrication (FFF) technology. The research focuses on optimizing powder loading, printing parameters and final processes, including debinding and sintering, to produce successful metal parts. Design/methodology/approach The optimal powder loading was identified by measuring mixing torque and viscosity at various temperatures. The filament was extruded, and printing parameters − particularly printing speed to ensure proper material flow − were optimized. Different filling patterns were also examined. After printing, the polymeric binder was removed and the parts were sintered to form the final metal components. Findings The optimal powder loading was determined to be 55 vol.%. The best surface quality was achieved with an optimized printing speed of 5 mm/s. Parts printed with various infill patterns were studied for differences in open, closed and total porosity, showing a strong link between porosity and infill pattern. Originality/value This comprehensive study provides new insights into manufacturing metal parts using FFF technology. It fills a gap in the literature regarding feedstock viscosity and shear rate in highly loaded metal filaments during FFF. Additionally, it uniquely examines the open, closed and total porosity of metal parts printed with different infill patterns.