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

## TL;DR

This paper introduces a new 3D printing method that improves the strength and reduces warping in carbon fiber-reinforced polypropylene parts by aligning fibers in a spiral pattern.

## Contribution

A novel shear screw printer design that enables helical carbon fiber orientation in 3D-printed composites is introduced.

## Key findings

- Helical carbon fiber orientation combined with a net printing arrangement enhances tensile properties.
- The method reduces anisotropy and significantly mitigates warping in printed parts.
- PP/CF composites with 15% CF showed improved mechanical performance at various layup angles.

## Abstract

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.