Experimental Assessment of the Effect of Print Orientation on the Geometrical Accuracy of Microfeatures in Multi-Material 3D Inkjet Printing

3D inkjet printing is an additive manufacturing technology that allows for the printing of multi-material features in the micrometre range with high accuracy, utilizing multiple printheads. In this study, two UV-curable materials, i.e. build material and water-soluble support material, are printed to create a specimen with overall sizes of up to 8x8x8 mm³, containing microcolumns and walls with widths ranging from 50 μm to 500 μm, equivalent to an aspect ratio between 0.01 and 0.5 (width/height). The objective of this study is to investigate qualitatively and to understand how the placement orientation of the object on the print platform affects the geometrical accuracy of the printed microfeatures. This study reveals that horizontal edges are most accurate when the specimen is rotated either around the print direction or the printhead axis by 45°. Conversely, horizontal edges that are parallel to the printing plane all exhibit a convex shape, most likely induced by the differing droplet coalescence behaviour between support/build material and build/build material interactions. The columns of consistent diameter (0.5 mm) and varying height (1, 2, and 3 mm) are printed successfully, although some are tilted in arbitrary directions. ... mehrThis tilting could be due to droplet variation between nozzles, skewed trajectories of printed droplets, or differences in layer height between materials. The majority of the printed thin walls, which are 50 μm wide, have collapsed, especially the vertical ones.