Enhancing interlayer bonding in short fibre-reinforced material extrusion additive manufacturing via a novel lift toolpath

Purpose Fibre-reinforced polymers offer enhanced in-plane mechanical properties in material extrusion (MEX) additive manufacturing, expanding its applicability. However, fibres have minimal impact on the mechanical properties in the build direction, limiting the industrial applications of MEX. This study aims to propose a novel method using a customised toolpath to enhance the interlayer mechanical properties of carbon fibre-reinforced nylon 6 (CF-PA6) structures in an easily accessible manner, requiring no hardware modifications. Design/methodology/approach The customised toolpath discretises the continuous bead into sub-sections and implements periodic vertical toolhead movement during fabrication. Three bead width configurations of MEX-fabricated CF-PA6 specimens were investigated using microscopy, thermal analysis and mechanical performance assessment. Findings In all configurations, the customised toolpath outperformed the conventional toolpath, showing significant increases in ultimate tensile strength (238%–513%), failure strain (70%–349%) and modulus (71%–164%). The main factors contributing to these improvements were found to be redistribution of fibre orientation and thermal effects. In addition, the enhancements became more pronounced as the print width increased. Originality/value This novel fabrication method improves the interlayer mechanical properties of CF-PA6 through software modifications alone. To the best of the authors’ knowledge, this approach has not been demonstrated on fibre-reinforced materials and may enable printing of high-performance polymers on less capable MEX printers.