Investigation on fiber laser cutting of polyacrylonitrile-based carbon fiber tow

Carbon fibers (CFs) are often chopped through conventional metal cutting tools. The wear of cutting tool is unavoidable, resulting in low productivity and unsteady product quality. In this work, cutting CFs by fiber laser was studied. The laser absorptivities of three types of CFs and sizing amounts were measured to evaluate their photothermal conversion properties. The cutting-off mechanism of CF was clarified by its kerf cross-sectional morphology and multiphysics simulations. The morphology, chemical composition and mechanical properties around the CF kerf were analyzed to investigate the characteristics of laser cutting method. In addition, the effect of laser parameters and sizing amounts on CF tow cutting were investigated. Results show that laser-cutting CF in the heat affected zone has poor mechanical properties compared to mechanical cutting CF, but composite nonwoven fabrics made by either of them have substantially equal tensile strength. The critical cutting-off speed of the three CFs has a linear relationship with the laser power. Compared to mechanical cutting, laser cutting of CF tows can reduce about 50% energy consumption. And the laser cutting speed can be adjusted within a large range, whereas the mechanical cutting speed is only determined within a relatively narrow range. This low energy consumption and speed-adjustable cutting method shows great potential to produce chopped CF-based high-quality composites.