Investigation of Variable Bead Widths in FFF Process

Fused filament fabrication technology provides the opportunity to produce complex objects with sophisticated interior features. Here, extruding variable bead widths for desktop 3D printers is presented in order to improve resolution and to decrease the build time. In the proposed method, the cross-section is continuously varied according to the geometric features associated with the layers. That is, thinner beads can be utilized to print features with higher accuracy such as the outer surfaces, edges/corners, and features with finer details. Larger beads could be employed to cover interior regions where the accuracy is not an important concern. In this paper, a comprehensive review on nozzles with variable bead widths is given. Then, new orientation-controlled extruder designs with rectangular orifice, which focuses on controlling the filament flow inside the nozzle to determine variable bead widths at the output of the nozzle, will be introduced. Numerical- and experimental analysis will be conducted to show comparatively the performance of the presented design. The repeatability of this process is also evaluated for nominal bead widths. The studies show that there is a good agreement between numerical and experimental results. The paper will be concluded with key points on the advantages of these proposed nozzle design.