Experimental Investigation and Taguchi Optimization of Print Parameters Affecting the Tensile Strength of 3D-Printed PLA Parts

This study systematically investigates and optimizes the influence of Fused Deposition Modeling (FDM) process parameters on the macroscopic tensile strength of polylactic acid (PLA) components. Addressing the need for predictable structural performance in 3D-printed parts, the novelty of this work lies in establishing a holistic, multi-stage optimization framework that maps the combined kinematic and geometric interactions of critical printing parameters directly to structural failure mechanisms and microstructural integrity. A systematic four-phase methodology was executed using a Taguchi L25 orthogonal experimental design to evaluate four manufacturing variables, namely layer thickness (P1), infill percentage (P2), nozzle retraction speed (P3), and nozzle travel speed (P4) across five discrete levels. Uniaxial destructive tensile testing on an ST Series Universal Testing System revealed that the initial ultimate tensile strength spanned a broad range from 20.04 MPa to a peak of 32.59 MPa. Signal-to-noise (S/N) ratio analysis (“Larger-the-Better”) and Analysis of Variance (ANOVA) at a 95% confidence level established layer thickness (P1) as the strictly dominant governing factor (F = 5.56), contributing 43.14% to total system variance. Parametric impact tracking confirmed secondary physical contributions from retraction speed (P3, 20.86%) and infill percentage (P2, 16.82%), while nozzle travel speed (P4, 3.90%) exhibited a negligible effect. Experimental confirmation testing using the identified optimal combination (0.20 mm layer thickness, 90% infill, 40 mm/s retraction speed, and 80 mm/s travel speed) yielded a peak ultimate tensile strength of 36.6 MPa, achieving a 12.3% improvement over the initial experimental maximum. Ultimately, this research offers a highly predictable, mathematically validated manufacturing strategy for converting empirical FDM adjustments into reliable and solid engineering components.