Orientation smoothing in multi-axis additive manufacturing

Abstract

In multi-axis processes, such as material extrusion like Fused Filament Fabrication (FFF), the orientation of the tool relatively to the workspace is usually set by the CAM software to an angle that is locally constant relative to the manufacturing surface. However, in the case of large curvature gradients or small curvature radius of the surface or the path, this method leads to significant variations of the tool orientation. These variation require large compensating movements of the axes to maintain the desired deposition tool orientation along the path. Kinematic constraints such as acceleration or jerk limits can lead to a reduction of the path velocity or noticeable positioning errors along the movement, as well as unwante vibrations, which means poor process conditions and defects in the parts. The paper presents a post path planning algorithm that allows smooth in of the tool orientation to avoid jerky compensation motion of the CNC system by varying the orientation within a defined tolerance. This tolerance depends on the deposition process, and is determined experimentally for a FFF process. The proposed methodology was successfully validated b the manufacturing of two sample parts using a robotic additive manufacturing cell.