Investigation of the mechanical properties of PLA and PLA-wood bolts fabricated via 3D printing with different print orientations

Abstract

This study investigates the torque resistance and fracture surfaces of pure PLA (polylactic acid) and PLA-Wood (wood flour added polylactic acid) bolts manufactured via Fused Deposition Modeling (FDM), compared to commercial Polyamide 6.6 (PA 6.6) bolts. M8×1.25×70 bolts were 3D-printed at varying orientations (0°, 45°, 90°) to evaluate the effects of printing direction on mechanical properties. The hardness, surface roughness, tensile strength, and flexural strength of pure PLA and PLA-Wood were analyzed. Results indicate that 0° print orientation yielded the highest mechanical strength, while significant degradation occurred at 45° and 90°. Surface roughness was minimized at 0° and peaked at 45°. PLA-Wood demonstrated inferior performance to pure PLA, and the torque resistance of PA 6.6 bolts was substantially lower than that of 0°-oriented pure PLA bolts. These findings provide critical insights for material selection and design in lightweight structural applications, assembly, and repair processes. © 2025, Bekir Cihad Bal. All rights reserved.