Increasing perpendicular alignment in extruded filament by an orifice embedded 3D printing nozzle

Abstract

The mixing of fibrous additives in the polymer base is being widely investigated for improving the mechanical properties of printed parts using fused filament fabrication (FFF). In this study, flow visualisation experiments and computational fluid dynamics (CFD) analysis were conducted on the flow channel of a nozzle with an orifice for enhancing the through-layer physical properties of the printed parts. Flow visualisation experiments were conducted on the flow channels of nozzles installed with orifices of various shapes. Using ball-milled carbon fibre in high-viscosity polydimethylsiloxane (PDMS) that imitates filament flow in FFF, the fibre angles were measured for different internal and external locations of the nozzle. The distribution of the fibre angles inside the nozzle was compared with the gradient of the flow field calculated for the same shape by CFD analysis. It was found that the orifice structure inside the nozzle increases the vertical alignment of the fibre. An abrupt increase in the extension rate at the exit of the orifice is considered to be the reason behind the rotation and vertical orientation of fibres inside the nozzle channel. Results presented in this work provide the basis for achieving improved through-plane physical properties of FFF printed parts through fibre alignment.

Keywords

• additive manufacturing
• fibre alignment control
• flow visualisation
• orifice embedded nozzle
• cfd analysis