Multi-response optimization of 3D printing parameters for copper-loaded PLA-based nanocomposites using RSM

Fused Deposition Modeling (FDM) is widely used for functional polymer parts, yet the process-property behavior of copper-loaded filaments remains underexplored. This study maps how five FDM parameters, nozzle temperature (190-210°C), layer height (0.1-0.3 mm), infill density (20-80%), raster angle (0-90°), and print speed (40-50 mm/s), govern the ultimate tensile strength (UTS) and ultimate flexural strength (UFS) of PLActive, a commercial PLA filament containing a nano-copper additive. A face-centered central composite design of 48 runs was executed, and reduced quadratic models were fitted by backward elimination. The UTS model retained ten terms and fitted well (R² = 98.22%, R²pred = 96.83%); the UFS model kept only ID, RA, and their interaction with a weaker fit (R² = 65.41%, R²pred = 57.85%). Raster angle and infill density dominated both responses, with a significant ID×RA interaction (F = 125.79, p < 0.001 for UTS; F = 6.03, p = 0.018 for UFS). Desirability optimization (D = 0.921) located the optimum at ID = 80%, RA = 90°, LH = 0.3 mm, PS = 50 mm/s, with predicted UTS = 49.6 MPa and UFS = 73.6 MPa, driven by beads aligned with the applied load. Validation reached 52.0 MPa and 76.3 MPa, inside the 95% prediction band.