Tribo-mechanical performance and microstructural characterization of FDM printed PLA and ABS components

Fused Deposition Modelling (FDM) has emerged as a transformative additive manufacturing technology enabling rapid fabrication of complex thermoplastic components, yet systematic understanding of how infill density simultaneously influences mechanical durability and tribological performance remains incomplete. This study presents a comprehensive comparative investigation of FDM-fabricated PLA and ABS components through integrated mechanical, tribological, and microstructural characterization across the complete volumetric infill density spectrum 0%, 25%, 50%, 75%, and 100%. The research establishes quantitative material-process-property relationships to support rational material selection and infill optimization. Experimental evaluation encompassed tensile testing, compressive testing, hardness measurement, pin-on-disc tribological analysis under dry sliding conditions, and scanning electron microscopy characterization of microstructural evolution. Results demonstrated that PLA exhibited superior tensile performance with strength increasing 150% from 20.3 ± 1.1 MPa at 0% infill to 49.7 ± 1.8 MPa at 100% infill, alongside exceptional tribological properties characterized by specific wear rate reduction from 2.24 × 10 -4 to 1.60 × 10 -5 mm 3 /Nm and friction coefficient decreasing from 0.65 to 0.28. Conversely, ABS demonstrated modest tensile gains 18.2 to 27.3 MPa, 50% improvement but excelled in compressive loading at intermediate densities, achieving 62.3-67.8 MPa at 50-75% infill 15-22% superior to PLA attributed to its amorphous structure enabling extensive plastic deformation and energy absorption through progressive cellular densification mechanisms. Statistical analysis ANOVA with Tukey HSD post-hoc testing confirmed significant material-infill interactions (p < 0.001) for all measured properties, establishing that optimal performance requires material-specific infill selection. The 50-75% infill range emerged as a cost-effective solution delivering 70-85% of maximum mechanical properties while achieving 25-35% material savings compared to full-density configurations.