The current paper studies the influence of geometrical parameters of the fused deposition modeling (FDM)-fused filament fabrication (FFF) 3D printing process on printed part strength for open source desktop 3D printers and the most popular material used for that purpose-i.e., polylactic acid (PLA). The study was conducted using a set of different nozzles (0.4, 0.6, and 0.8 mm) and a range of layer heights from the minimum to maximum physical limits of the machine. To assess print strength, a novel assessment method is proposed. A tubular sample is loaded in the weakest direction (across layers) in a three-point bending fixture. Mesostructure evaluation through scanning electronic microscopy (SEM) scans of the samples was used to explain the obtained results. We detected a significant influence of geometric process parameters on sample mesostructure, and consequently, on sample strength.
Keywords: additive manufacturing; anisotropy; desktop 3D printing; digital fabrication; fused deposition modeling; fused filament fabrication; interlayer bonds; mechanical strength; polylactic acid.