Improved Model and Experimental Validation of Deformation in Fused Filament Fabrication of Poly Lactic Acid
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Description: This code supports the following paper: Improved Model and Experimental Validation of Deformation in Fused Filament Fabrication of Poly Lactic Acid Bas Wijnen and Joshua M. Pearce RepRaps (self Replicating Rapid prototypers), which 3-D print objects using fused filament fabrication (FFF) have evolved rapidly since their open source introduction. These 3-D printers have primarily been limited to desktop sizes of volumes of ~8 cubic cm, which has limited the attention of the scientific community to investigating deformation of common thermoplastics such as polylactic acid (PLA) used in FFF printing. The only existing physically relevant deformation model was expanded to use a physics-based temperature gradient instead of a step function. This was necessary to generalize the model to 3-D printing in a room temperature environment without a heated chamber. The thermal equation was calibrated using thermal measurements and validated by measuring curvature in printed objects. The results confirm that this is a valid model for predicting warpage of thin vertical walls of PLA. Additionally, the effect of annealing was examined. It was found that at a temperature of 50°C, no shrinkage or crystallization takes place, but at 90°C the rapidly crystallizes to around 20% crystallinity. This indicates that heated bed temperatures should be maintained at 50oC or lower to avoid print failure with PLA. At 90°C, the annealing is accompanied by a 5% size decrease in both horizontal dimensions, but an 8% increase in the vertical dimension. Thus, the volume decreased by only 3%, indicating potential methods of improving slicing of printing large PLA objects with FFF.