Procedure to improve the surface fidelity of additive manufactured parts via direct slicing tessellation

Abstract

Part appearance issues due to dimensional and shape inaccuracies (fidelity) hinder the use of additive manufacturing processes to obtain final products. Inaccuracies come from process parameter definition, post-processing operations, and the slicing process. Regarding the slicing procedure, the conventional approach is the indirect slicing of a tessellation that approximates the part model. Layer computation is straightforward in this method but introduces dimensional deviations for curvilinear surfaces. Direct slicing minimizes these deviations, but computation and layer representation are complex. This work blends both solutions, explaining how to build an improved tessellation from direct slices that can be introduced and processed in usual slicing programs. Two shapes , a simple hemisphere and a component of a retail product (a hair dryer nozzle), were printed by Fused Filament Fabrication (FFF), using conventional indirect slicing with different tessellation’s resolutions and the proposed Direct Slicing Tessellation (DST). The resulting samples were measured using a 3D scanner. Compared with a reference sample printed from a Computer-Aided Design (CAD) model discretized with a tolerance <6μm, maximum deviations were found on more areas of conventional indirect samples and with higher values (from 0.13 to 0.16 mm) than in the case of the DST samples (with maximum deviation of 0.1 mm at few points on the surface). Additionally, DST files are around ten times smaller than reference files. Finally, the deviation between the CAD model and the representation on the resulting surfaces of zebra stripes and mean curvature show that the proposed solution enhances the printed surface fidelity compared to the conventional indirect slicing.