Mechanical, tribological, and thermal behavior of PLA and PLA+: influence of FDM process parameters and future research directions—a comprehensive review

Abstract Since the late 1980s, additive manufacturing (AM) has developed rapidly and is now considered a transformative manufacturing technology. Fused deposition modeling (FDM) remains one of the most popular AM techniques, offering an ideal combination of simplicity, affordability, and accessibility. This review aims to critically analyze and summarize the influence of key FDM process parameters, i.e. layer thickness, infill density, infill pattern, nozzle temperature, print speed, build orientation, etc, on the mechanical, tribological, and thermal properties of polylactic acid (PLA) and its composite variant PLA+ produced using FDM. Layer thickness and printing speed usually have an inverse relationship with mechanical strength, though certain exceptions exist. On the other hand, tribological properties are mainly affected by infill pattern and infill density, while thermal properties are primarily influenced by nozzle temperature and layer thickness. Optimizing these parameters can enhance layer adhesion and thermal stability. These insights facilitate the optimization of FDM process parameters to tune the properties of PLA and PLA+, thereby enhancing their suitability not only for prototyping but also for practical, real-world applications. Finally, various approaches, including statistical techniques and machine learning methods, are discussed for optimizing printed part properties, thereby enhancing the efficiency and reliability of PLA and PLA+ in 3D printing.