Influence of process parameters of fused filament fabrication on the Tensile and Specific Strength of Carbon fiber-reinforced polyethylene terephthalate glycol polymer

Carbon fiber-reinforced polyethylene terephthalate glycol (PETG-CF) has emerged as a promising material for lightweight structural applications owing to its favorable mechanical properties and printability. However, the combined influence of fused filament fabrication (FFF) process parameters on its tensile performance and material efficiency remains inadequately understood. This study experimentally investigated the effects of infill shape, print speed, layer height, infill density, and raster angle on the tensile strength and specific strength of PETG-CF using a Taguchi orthogonal array. Tensile tests were conducted in accordance with ASTM D638, followed by analysis of variance (ANOVA), signal-to-noise (S/N) ratio analysis, and scanning electron microscopy (SEM) fractography. The maximum experimental tensile strength of 24.38 MPa was achieved using the honeycomb infill shape, whereas the highest specific strength of 20.98 MPa·cm³/g was obtained at 70% infill density, demonstrating that the maximum tensile strength does not necessarily correspond to the highest material efficiency. ANOVA identified infill shape and infill density as the dominant factors affecting tensile strength, whereas infill shape and print speed primarily influenced specific strength. Optimum tensile strength of 26.538 MPa and a specific strength of 21.22 MPa·cm³/g were obtained during confirmation experiments, representing improvements of 8.85% and 1.14%, respectively, over the best original experimental values. SEM observations further revealed improved interlayer continuity and polymer fibrillization in the higher-strength specimens. These findings demonstrate the importance of considering both tensile performance and material efficiency when optimizing FFF parameters for PETG-CF components.