Tribological Performance of FFF-Printed PLA and PLA-Wood Parts: The Effects of Infill Architecture, Heat Treatment, and Water Absorption

Polymer components fabricated via fused filament fabrication (FFF) are frequently exposed to friction and wear under diverse environmental conditions in various engineering applications. The tribological performance of these components is influenced by both the printing parameters employed during fabrication and subsequent post-processing and service conditions. Previous studies have generally investigated the effects of printing parameters or post-processing steps separately. However, a comprehensive evaluation of in-service performance requires the sequential consideration of these factors. This study aimed to evaluate the tribological performance of FFF-printed PLA and PLA-Wood specimens through a sequential approach considering the infill architecture, heat treatment, and subsequent water absorption. The findings indicate that the best-performing infill architecture among the investigated configurations was the rectilinear pattern at an 80% infill density, which exhibited the lowest volumetric wear loss among all printing configurations. The best-performing heat treatment conditions varied by material and were determined to be 90 °C for 15 min for PLA and 90 °C for 45 min for PLA-Wood, reducing volumetric wear loss from 17.97 to 14.32 mm3 (approximately 20%) and 24.92 to 22.36 mm3 (approximately 10%), respectively. Moreover, water absorption largely eliminated the heat-treatment-induced improvement in PLA, with volumetric wear loss increasing to 17.93 mm3, whereas the improvement was substantially retained in PLA-Wood, which exhibited a wear loss of 22.67 mm3 after water absorption. Overall, the findings demonstrate that improvements in wear resistance achieved through processing may not be equally retained after subsequent environmental exposure and that this response depends on the material composition.