Additive layer manufacturing of composite components: Combining short fibre composite feedstocks with curved layer fused filament fabrication

Fused filament fabrication (FFF) is a low cost additive manufacturing technique capable of constructing detailed components from 3D data in a wide range of feedstock materials. The use of short fibre composites in FFF has recently been shown to introduce alignment of short fibres within individual extruded tracks of components manufactured using this technique. Curved layer FFF (CLFFF) is the process of including dynamic z movements to individual layers in FFF in order to improve surface finish and mechanical performance of FFF components. This method shifts from traditional methods that use static z values and manufacture components from flat layers that typically exhibit an inherent weakness in the z direction across individual layer boundaries. This study demonstrates the use of CLFFF in tandem with a composite feedstock consisting of a Nylon PA6 thermoplastic matrix reinforced with 30 wt% short glass fibres. Test specimens are manufactured following ASTM D638 using conventional and CLFFF toolpathing techniques. Preliminary results have indicated promising mechanical properties of manufactured parts under tensile load, although CLFFF components only demonstrated 70 % of the performance of their conventional counterparts. Electron microscopy of fractured sample surfaces has also been conducted and has revealed local alignment of short glass fibres within the vector direction of the extruded tracks of the composite feedstock material.