Dual nozzle 3D printing strategy to improve the surface quality of continuous glass fiber reinforced polyamide 6 composites

A dual‐nozzle 3D printing technique was proposed to prepare continuous glass fiber reinforced PA6 (CGF/PA6) composites with sandwich structure. Short glass fiber reinforced PA6 filament was used for printing the surface layer and CGF/PA6 filament was used for inner part to provide high‐mechanical performance. Morphology of CGF/PA6 filament and the properties of printed composites samples were investigated. Printing process parameters were systematically optimized. The results showed that when CGF/PA6 part thickness of the composites samples was 2.8 mm, the flexural strength and flexural modulus, notched impact strength and interlaminar shear strength of the printed products can reach 275.4 MPa, 10.8 GPa, 168.2 kJ/m2, and 26.5 MPa, respectively. The dual‐nozzle 3D printing strategy in this work was of great significance for the precision fabrication of continuous fiber reinforced thermoplastic composites (CFRTPC), which can be widely used in aerospace, automotive, wind turbine blades, shipbuilding, and other industrial fields due to their excellent mechanical properties and ability to resist vibration and corrosion. Preparation process diagram and sample of continuous fiber reinforced PA6 composites with sandwich structure.