TOOLPATH SYNTHESIS AND MECHANICAL PROPERTIES IN MULTIPLEXED FUSED FILAMENT FABRICATION

Material Extrusion additive manufacturing (MatEx) based on Fused Filament Fabrication (FFF) enables inexpensive bottom-up fabrication of thermoplastics and thermoplastic composites for structural, biomedical, energy, and tooling applications. The to-scale realization of these lab-scale innovations in MatEx depends significantly on mass customization, i.e., increasing the overall process throughput (including that of post-processing) while retaining high resolution and 3D geometric capability that is crucial to additive manufacturing. This paper addresses a throughput-resolution-geometry tradeoff that limits such mass customization via a Multiplexed FFF (MF3) approach that combines a unique dynamic-extrusion based toolpath strategy with the existing multi-extruder-single-gantry machine architecture. MF3 has been demonstrated in one recent work. But this past effort does not enable geometrically generalizable and automated synthesis of the atypical MF3 toolpath, does not investigate the unconventional scaling of throughput while considering partial infills that are common in additive manufacturing, and does not explore the mechanical effects of the section-section junctions created by MF3. This work establishes an automated and generalizable toolpath synthesis approach and derives analytical laws for build time reduction, both of which are prerequisites for rational process planning. A multi-extruder multi-section thermal model is created to reveal the atypical temperature history of section junctions in MF3 and is combined with mechanical testing and modelling to deconvolute geometric and thermal effects on the mechanical behavior of the section-section junctions.