Gas assisted fused deposition modeling: effects of assist gas parameters on print quality and properties

Abstract

Fused deposition modeling (FDM) is the most widespread type of additive manufacturing technology. However, the extrusion based process limits the interfacial bonding strength and dimensional accuracy of the printed parts. This paper presents a gas assisted nozzle to localized heating around filament through hot air flow, to maintain the temperature of the filament stays and improve the quality of the bonding. The impact of assist gas temperature (55 degrees C-295 degrees C), flow rate (1 L/min-3 L/min) and pressure (0.2 MPa-0.5 MPa) on filament extrudation, layer consolidation, and the printed parts thermal properties, as well as the mechanical properties were investigated. It is shown that the swell ratio of extruded filament and dimensional difference of layer thickness can be controlled by varying the assist gas parameters. The assist gas raises the temperature of the exudate and the existing layer near the nozzle, leading to 73.6 % increase in crystallinity, 19.4 % increase in tensile strength and 48.4 % impact strength. The gas assisted pre-heating approach represents an effective way to increase interlayer strength can be employed as an additional control parameter to improve the thermal and mechanical properties of the FDM printed parts.