Supportless 3D-printing of non-planar thin-walled structures with the multi-axis screw-extrusion additive manufacturing system

Thin-walled structures, including the hollow tubes and curvature shells, are integral to a number of engineering applications. Manufacturing those structures with the recently emerged additive manufacturing scheme, such as the screw-extrusion additive manufacturing (SEAM), can greatly improve the manufacturing efficiency and reduce the overall manufacturing cost. Yet, the support structure is often required to print such structures, adding undesired weight to the otherwise light-weight structures. In this work, the SEAM is integrated with a 6-axis industrial robot to enable the dynamic reorientation of the nozzle, stay perpendicular to the deposition surface. As a result, the geometrically-complex hollow tubes and arc-like thin shells can be directly printed without any support structure. In addition, by selectively designate the infill directions and starting points, a light-weight honeycomb-infilled curved shell can be directly printed without any additional processing. Mechanical tests have also shown the conformally-printed curved parts exhibit higher strength than the conventionally-printed counterparts. The result from this work can hopefully incentive new insights in developing novel strategies for 3D-printing functional thin-walled structures.