Variable Extrusion Width for Interlocking Features in Fused Filament Fabrication 3D Printing
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Following from developments in continuously variable extrusion width in fused filament fabrication additive manufacturing, this work explores the combination of in-plane bead width variation with bead trajectory variation as a technique to improve in-plane strength in polymer material extrusion additive manufacturing. Sinusoidal in-plane waveforms are used for the extruder trajectory instead of maintaining a straight line. The varied bead width, in conjunction with the non-straight bead trajectory, reduces anisotropy of strength within the layer. The findings apply to fully dense infill of single layers, commonly called horizontal perimeters in common slicing/toolpath planning computer programs. Experimental tensile testing results show a 48.6% reduction in anisotropy of tensile strength driven by 43% and 29% increases in the ultimate tensile strength in the 0° and 45° orientations, respectively. However, this comes at the cost of 99.6% reduction in toughness in the 90° orientation. We also present the principal concept behind the machine code generating script, that allows for the increase and decrease of the extruded bead width continuously along the extruded bead.