Browsing by Subject "3D parts"
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Item Computed Axial Lithography for Rapid Volumetric 3D Additive Manufacturing(University of Texas at Austin, 2017) Kelly, Brett E.; Bhattacharya, Indrasen; Shusteff, Maxim; Taylor, Hayden K.; Spaddacini, Christopher M.The vast majority of additive manufacturing processes today operate by printing voxels serially point-by-point to build up a 3D part. In some higher throughput techniques, for example optical printing methods such as projection stereolithography [1], [2], parts are printed layer-by-layer by curing full 2D (very thin in one dimension) layers of the 3D part in each print step. In this work, we demonstrate a new technique which prints entire parts all at once and eliminates layering. The approach, termed Computed Axial Lithography (CAL), is based on tomographic reconstruction, with mathematical optimization to generate a set of projections to optically define an arbitrary dose distribution within a target volume and to cure the entire volume simultaneously. Volume-at-once fabrication of complex geometries is achieved using a custom system built from a DLP projector and a rotating resin volume. This technique can be used to expand the range of printable geometries in additive manufacturing and relax constraints on factors such as overhangs in topology optimization. The method also vastly increases print speed for 3D parts. We show complex and overhanging geometries printed in situ without layering.Item Planning Freeform Extrusion Fabrication Processes with Consideration of Horizontal Staircase Effect(University of Texas at Austin, 2015) Ghazanfari, Amir; Li, Wenbin; Leu, Ming C.; Landers, Robert G.An algorithm has been developed to estimate the “horizontal” staircase effect and a technique is proposed to reduce this type of geometrical error for freeform extrusion fabrication processes of 3D “solid” parts. The adaptive rastering technique, proposed in this paper, analyzes the geometry of each layer and changes the width of each line of the raster adaptively in order to reduce the staircase error and increase the productivity simultaneously. For each line, the maximum width that results in a staircase error smaller than a predefined threshold is determined for decreasing the fabrication time or increasing the dimensional accuracy, or both. To examine the efficacy of the proposed technique, examples are provided in which staircase errors and fabrication times are compared between uniform and adaptive rastering methods for each part. The results show a considerable improvement in accuracy and/or fabrication time for all parts studied when using the adaptive rastering technique.