A novel single-stroke path planning algorithm for 3D printers using continuous carbon fiber reinforced thermoplastics

Recently, 3D printers using continuous carbon fiber as a material have attracted considerable attention from researchers due to its high mechanical properties and the potential to reproduce complex shapes. Although the main advantage of 3D printing is that complex shapes can be produced through a simple process, very few studies have evaluated samples with complex shapes containing continuous fibers. Unlike pure resin or materials mixed with short fibers, carbon fiber filament contains long, strong fibers, which requires additional steps such as cutting the filament multiple times to create complex shapes. This study proposes a path planning algorithm for the print head of a fused deposition modeling (FDM) 3D printer using filaments reinforced with continuous fiber bundle. The proposed method generates a single-stroke path that can be printed continuously without cutting the filament for each layer. Specifically, an Eulerian graph is created from the print pattern, and the path is generated using Hierholzer’s Algorithm with constraints. By visualizing the generated paths, we confirmed that the paths generated by the proposed method do not interfere with each other. Furthermore, samples were fabricated by using a 3D printer capable of printing with continuous fibers, and the inside of these samples were observed with X-ray computed tomography (CT). In addition, the gaps that occur during actual printing can be suppressed by adjusting the parameters of the algorithm. Finally, we have shown that the proposed method can be applied to geometries with varying wall thicknesses and aperiodic patterns using the Voronoi diagram.