Fabricating Efficient and Biocompatible Filament for Material Extrusion-Based Low-Cost Additive Manufacturing: A Case Study with Steel

Abstract

The production of various 3D-printed metal or ceramic parts via fused deposition modeling (FDM) or fused filament fabrication (FFF) is gaining tremendous interest. This is because FDM or FFF are cost-effective and have comparatively faster processability. FDM or FFF are material extrusion-based additive manufacturing processes in which the filament is extruded through a nozzle at a high temperature, and the object is formed by its layer-by-layer deposition. Irrespective of the metal/ceramic precursors, the choice of binder/carrier is crucial for developing 3D-printed parts using FDM of FFF techniques. The optimization of processing parameters determines the perfectness of the binder/carrier chosen for successful 3D printing. In the case of multi-component metal alloy preparation, the binder tightly holds the alloying components close to each other and helps to maintain their stoichiometry. A suitable carrier holds ample alloying components while retaining enough flexibility and strength to the filament for printing. Compatibility between the binder and carrier can synergistically improve the 3D printing. Polyvinyl pyrrolidone (PVP) has been chosen as a highly processable and biocompatible binder in this work, while thermoplastic polyurethane (TPU) is a biocompatible carrier for the PVP-bound metal. The metal powder having a composition of Fe-1.5Ni-1.5Cu (as per the wt.%) has been used to investigate the efficacy of the binder and carrier. The binding of metal powder with PVP dispersion, melt mixing of PVP-bound metal powder with the TPU, extrusion of the TPU/PVP-bound metal (TPM) composite, 3D printing of the extruded filament (containing 40 vol.%, i.e., 82 wt.% of metal) using a low-cost 3D printer, and debinding of the printed product/s at different heating conditions have been thoroughly optimized and successfully standardized.