• Optimizing layer height, extrusion temperature, and printing speed improves tensile strength by up to 32% and flexural strength by 28% in 3D-printed CFRP composites.
• Reduced void content and enhanced fiber-matrix adhesion are key microstructural factors contributing to improved mechanical properties.
• The study establishes a process-property relationship that enables tailored manufacturing of CFRP parts for structural applications.
• The optimal parameter set offers a practical benchmark for industrial adoption of FFF-based CFRP production.