Development of mathematical model for surface roughness estimation in material jetting 3D printed parts

This research investigated the modeling of three relatively different surface profiles, based on outer layer contour, internal raster, and a combination of these two, to estimate the surface roughness of material jetting 3D printed parts. Theoretical and empirical modeling was used to determine the relationship between build orientation and layer thickness with surface roughness. Results indicated that the developed surface roughness model can be utilized to estimate the surface roughness value of other surface profiles built through the same machine using material jetting technology or even other additive manufacturing systems like fused filament fabrication. Also, the validation using existing models showed a significant reduction in the prediction error (1.008%) and provides a more accurate surface roughness model for predicting surface roughness values. To minimize the required surface roughness value in the material jetting 3D printed parts, a surface roughness optimization methodology based on changing the build orientation is suggested in this article. An expression of the direction of build orientation is presented and the relation between the surface roughness and build orientation is investigated taking color coding environment into consideration. The validity and effectiveness of the proposed optimization methodology are tested by simulation and experimental results.