Gas-assisted technology enhanced micro-dimensional accuracy in 3D printing

Fused Filament Fabrication (FFF) is restricted from high-precision manufacturing applications due to the poor dimensional accuracy of the printed parts. Gas-assisted 3D printing, a novel additive manufacturing technology, addresses this limitation by injecting continuous high-pressure and high-temperature gas into the interface between the nozzle wall and molten filament, which creates a full-slip condition that modifies the polymer's shear rate field. This study investigates the mechanisms of layer accuracy enhancement in gas-assisted 3D printing through theoretical analysis and experimental validation. A geometric model including both the full-stick and full-slip zones within the nozzle was established to analyze the shear rate field, shear stress field, and deformation behavior of the molten filament. High-speed imaging and scanning electron microscopy (SEM) were utilized to characterize the dimensional deviations of extruded filaments and deposited layers. Experimental results confirm that gas-assisted 3D printing significantly improves the micro-dimensional accuracy of deposited layers. For nominal layer thicknesses of 100 μm and 300 μm, the fluctuation of deposited layer thickness was reduced to within ±5 μm and ±10 μm, respectively. Additionally, the surface quality of the Z-seam was notably enhanced. This study indicates that, in the gas-assisted 3D printing process, the melt undergoes elastic recovery under zero shear stress in the full-slip zone, which suppresses dimensional instability and improves the micro-dimensional accuracy of printed parts.