Abstract: Continuous fiber 3D printing technology combines the advantages of high mechanical properties of composite materials and flexible manufacturing of 3D printing, which has great development potential. However, there are some forming defects in the parts produced by the existing process, which affect the large-scale application of this technology. By using self-developed 3D printing equipment, aramid fiber reinforced PLA test parts were manufactured. The molding quality of the test parts was studied and the conditions for slip defects were proposed. The defects of fiber bundle slip, peeling, fracture and interlayer pores were systematically studied. Four process optimization methods such as the printing speed, path angle, cooling system and nozzle shape were proposed and relevant experiments were designed for verification. The results show that optimizing velocity, path angle and cooling system can reduce the slip distance of fiber bundle by 45%, 81% and 50%, respectively, and optimizing nozzle shape can reduce the fracture rate by 90%. The research provides ideas and solution for the design and manufacture of composite materials based on 3D printing.

Key words: 3D printing, continuous fiber, defects, optimization method, composites