Circular Shear Printing of Spiral-Oriented CF-PP Components for Enhanced Mechanical Performance and Warp Mitigation.

Extrusion-based printers have attracted much attention for their simplified printing process and broader material compatibility. Carbon fibers (CF), known for their excellent mechanical properties, are incorporated into polypropylene (PP) printing materials. This study presents a shear screw printer (SSP) with a modified screw design. The SSP generates torsional shear forces, enabling helical orientation of CFs within PP/CF composites. The study also compares the SSP's performance with that of a conventional screw printer (CSP). PP/CF composite specimens containing 15% CF were printed at four different layup angles: 0°, 45°, 90°, and ±45° (net). The results show that combining CFs' helical orientation with a net printing arrangement can effectively enhance tensile properties while reducing anisotropy. Furthermore, this approach can significantly mitigate warping in printed parts.