Method for the Calculation of Local Bead Volume in Multi-Axis Additive Manufacturing

Abstract

In recent history, Multi-Axis Additive Manufacturing enjoys increasing attention for both industrial and research application. In comparison to traditional processes, the additional rotation axes enable parts to be printed with greater design flexibility, while reducing the need for support structures. The multi-axis motion additionally allows for optimization of structural properties of the parts. However, curved-layer printing requires significantly higher effort for planning and computation, as the layers exhibit curvature in their shape and feature local variations of the layer height and bead width. Consideration of these properties is often neglected in the development of path planning methods, although they pose a significant influence to the optical and structural quality of the printed parts. Local over- or under-extrusion can result in material accumulation or voids within the part and need to be avoided. Additionally, some Multi-Axis Additive Manufacturing processes like Directed Energy Deposition are especially prone to errors in practice, as the melt-pool behavior is hard to model and predict accurately. This paper introduces a method for the precise calculation and adjustment of local bead volume, as a possible solution to these problems. The method processes existing Cartesian paths and uses a model of the bead geometry to simulate the extrusion by rasterization. The method considers printing head orientation, as well as neighborhood information of adjacent beads and builds a volumetric map of the paths. Local extrusion volume is then determined for each waypoint of the path from this volume map and provided to the printer along with the G-Code, enabling adjusted volume deposition both in advance and during the process by iterative path-adaptation. The provided implementation is able to achieve favorable results for both use-cases but proves especially beneficial for the latter.