Comparison of the effects of multiaxis printing strategies on large-scale 3D printed surface quality, accuracy, and strength

The purpose of this study is to determine impact of several multi-axis 3D printing strategies on buildability, surface quality, accuracy, and strength of large scale single-walled object (printed in a so called vase mode). To achieve this goal, test objects were printed using four different printing strategies by an industrial robotic arm and a pellet-fed screw extruder. The strategies tested in this study are regular 3-axis deposition with planar layers, 5-axis deposition with planar layers, 3-axis deposition with nonplanar layers, and 5-axis deposition with nonplanar layers. Custom scripts for nonplanar slicing and for tilt control during multiaxis printing were developed to achieve these prints and are explained in this study. The results were evaluated using 3D scanning and mechanical testing, and surface accuracy, surface roughness, and layer adhesion strength were compared. The most important findings are (1) 5-axis motion alone does not improve the results of the printing; (2) while nonplanar printing can improve surface quality, its usability is geometry dependent; and (3) multi-axis nonplanar printing, even with partial tilt (30°) can expand printability with enhanced quality to at least 75° overhang angle. The future potential of these methods and the requirements to achieve them are discussed.