Influence of Manufacturing Route on the Mechanical and Thermal Performance of Polylactic Acid Fabricated by Fused Deposition Modeling and Compression Molding

This study compares the mechanical and thermal performance of polylactic acid (PLA) specimens fabricated by fused deposition modeling (FDM) and compression molding (CM) using the same PLA filament and processing temperature. Six FDM raster configurations (S1–S6) were evaluated and compared with CM specimens. Tensile, flexural, impact, hardness, and thermogravimetric analyses were conducted to investigate the influence of manufacturing method and raster orientation. The results showed that mechanical properties were strongly dependent on raster configuration. Among the FDM specimens, the 90° raster orientation (S3) exhibited the best performance, with tensile strength and modulus increases of 73.1% and 44.7%, respectively, compared to CM. S3 also achieved the highest flexural strength, exceeding CM by 7.7%, while maintaining a comparable flexural modulus. Impact behavior was significantly affected by raster architecture, whereas CM specimens showed higher hardness due to their denser structure. Thermogravimetric analysis revealed similar degradation behavior for both manufacturing methods, with major decomposition occurring between 250–350 °C. S3 displayed the highest degradation peak temperature (≈335 °C), indicating slightly improved thermal stability. The findings demonstrate that optimized raster orientation, particularly the 90° configuration, can substantially enhance the performance of FDM-printed PLA, making it a promising alternative to compression molding for structural applications.