Combined Influence of 3D Printing Parameters and Thermal Treatment on the Tensile Strength of FGF-Printed PLA Components

This study investigates the mechanical performance of polylactic acid (PLA) components fabricated using Fused Granular Fabrication (FGF), a variant of extrusion-based 3D printing that uses polymer granules instead of filament. The influence of three key process parameters: build orientation, infill pattern, and layer height, on the tensile strength and elastic behavior was assessed. Additionally, the effect of thermal post-processing via annealing was evaluated to determine its role in reducing anisotropy and improving interlayer bonding. An L9 Taguchi orthogonal array was employed to optimize experimental efficiency, and statistical analysis was performed using ANOVA and signal-to-noise ratio methods. The results show that build orientation has the most significant impact on ultimate tensile strength (UTS), contributing 78.34% of total variation in the as-printed condition. Annealing was found to enhance UTS for specimens printed at non-optimal orientations (45° and 90°), with increases up to 28%, while its effect on optimally printed samples (0°) was negligible. Fracture analysis confirmed predominantly brittle behavior across all conditions, with crack propagation aligning with build direction in non-annealed samples. The annealed specimens displayed improved cohesion and non-directional fracture behavior. The findings suggest that proper selection of printing parameters, combined with thermal treatment, can reduce anisotropy and enhance the reliability of PLA parts produced via FGF.