Optimization of 3D-Print Parameters for PLA–Mission Grass Biodegradable Composites

This study is aimed to maximize the ultimate tensile strength (UTS) in accordance with ASTM D638 standards. A Box-Behnken design integrated with RSM was employed to model the influence of selected parameters: print speed (60–100 mm/s), layer height (0.1–0.3 mm), and infill density (20–60%). Mission Grass (Pennisetum polystachion) was chosen as it is perennial and widely available in tropical regions, rich in cellulose and low density. However, this fiber is not well explored compared to conventional natural fibers such as jute and flax. Incorporating Mission Grass into PLA composites offers a sustainable approach for 3D-printing. PLA Mission Grass composite specimens were fabricated and tested using a horizontal tensiometer (KIPL–PC 2000). The empirical study established a model to optimize the Peak Load response of PLA–natural fiber fabricated composites. The developed model exhibited moderate predictive capability (R2 = 0.75). After optimization, a parameter combination comprises print speed (82.4 mm/s), layer height (0.2 mm), and infill density (36.4%), yielded a peak load of 591.86N. Overall, the study provided a quantitatively process for optimization to enhance predictive robustness and resolve multivariable dependencies in FDM-based PLA–natural fiber fabricated composites.