Dimensional accuracy and mechanical behavior of 3D-printed polylactic acid/cashew nutshell particle bio-composites

This study evaluates the dimensional accuracy and mechanical behavior of 3D-printed bio-composites consisting of a Polylactic Acid (PLA) matrix reinforced with cashew nutshell (CNs) particles at 0.5, 1.0, and 2.0 wt%. Tensile and flexural specimens were manufactured via Fused Deposition Modeling (FDM) and compared to neat PLA. Dimensional accuracy was assessed against CAD models, while mechanical properties were tested following ASTM D638 and D790 standards, supplemented by scanning electron microscopy (SEM) for fracture analysis. Results indicated that while common printing defects were absent, thermal warping occurred in all specimens due to uneven cooling. Dimensional accuracy for PLA/CNs specimens (48.75–96.92%) was lower than neat PLA (86.83% to 99.52%), attributed to restricted shrinkage and increased thermal gradients caused by the filler. Mechanically, Young’s Modulus remained unchanged, and while the ultimate tensile stress decreased slightly, it remained within standard ranges for 3D-printed PLA. Conversely, flexural stress increased with higher CNs content. SEM analysis revealed that CNs particles improved bead bonding. Despite the lower dimensional precision, the high repeatability of the process suggests that proper calibration can optimize the production of these sustainable bio-composites.