Search

The recycled carbon fiber reinforced polymer (rCFRP) based on fused filament fabrication possesses many problems, such as high porosity and poor interlayer bonding. In view of this, an overflow extrusion‐annealing process is proposed in this paper, in which rCFRP is prepared by using the extrusion flow higher than the theoretical requirement, and then annealed. Experimental outcomes demonstrate that recycled carbon fiber reinforced Nylon 6 (rCF/PA6) composites with a carbon fiber content of 35.5 wt% were successfully prepared by a developed screw extrusion 3D printer. The pore size distribution and micromorphology of rCF/PA6 composites show that the process can eliminate the inter‐bead pores, reduce the total porosity, and effectively promotes the interline and interlayer bonding. Mechanical properties tests reveal that compared with pure PA6, the tensile strength of rCF/PA6 composites prepared by this process is increased by 87.4% (100.41 MPa), and the flexural strength is increased by 71% (150.5 MPa). Therefore, this process has great potential in the preparation of high‐performance rCFRP, and is expected to provide a new perspective for the industrial application of 3D printed rCFRP in the future. Highlights: Utilize recycled carbon fiber (rCF) in screw extrusion 3D printing.Prepare rCF/PA6 composites with a high rCF content.Eliminate inter‐bead pores based on overflow extrusion.Enhance interline and interlayer bonding of composites based on annealing. [ABSTRACT FROM AUTHOR]

Fused Deposition Modeling (FDM), a widely-utilized additive manufacturing (AM) technology, has found significant favor among automotive manufacturers. Polypropylene (PP) compound is extensively employed in the production of automotive parts due to its superior mechanical properties and formability. However, aiming at the problem of poor dimensional accuracy of pure PP parts, the quality of products can be enhanced by optimizing the combination of processing parameters. In this paper, the dimensional accuracy of 3D-printed components made from pure PP material is investigated. Key influencing factors such as infill percentage, infill pattern, layer thickness, and extrusion temperature are considered. To gain a deeper understanding, fluid simulation is conducted, and mathematical models are established to correlate processing parameters with dimensional accuracy. Furthermore, the Taguchi's experiments are designed and the experimental data are subjected to rigorous Signal-to-Noise ratio and ANOVA analyses. Within the experimental range, the lower extrusion temperature, infill percentage and layer thickness yield the best dimensional accuracy. Considering the influence factors of X, Y and Z directions, the optimal processing parameters for PP prints using screw extrusion 3D printers are determined as follows: an extrusion temperature of 210 °C, an infill percentage of 40 %, a layer thickness of 0.3 mm, and a concentric circle infill pattern. This study provides reference value for the subsequent improvement of the dimensional accuracy of the printed parts.