<p>Contemporary path planning software used in Large Scale Additive Manufacturing with Metal (LSAMM) builds is typically oriented towards generating evenly spaced, layer-based contours which are gravity aligned (GA). These contours are then converted into generic machine code for use with a printing system. Layer-based approaches to generating AM paths also make a host of assumptions which affect the printing process and final geometry for achieving near net shape. Tessellation of curved surfaces for a CAD model represented as an .STL file can cause imprecision in the representation of curvature. Additionally, separating a part representation into 2.5D layers means that geometry outside of the slice plane is subject to the stair-step effect, which decreases the accuracy of the printed part. By stepping away from the 2.5D methodology towards a true 3D approach, it is possible to dramatically increase the capability of AM systems to achieve accurate near-net shape parts. Commercially available slicing software does not offer an all in one package for generating and integrating GA and NGA segments with low level control of the welding process, and seldom offers capabilities to control the orientation of the deposition head. By considering a novel framework for organizing print system trajectory data for an AM build, it is possible to easily control low level process parameters such as print travel speed and tool orientation, and to rapidly generate robot programs with minimal operator input. Non-gravity aligned (NGA) techniques can be implemented during wire and arc additive manufacturing (WAAM) with a new organization of path trajectories. The flexibility of a 6DOF manipulator allows for both the translation and rotation of the welding torch, which is not taken advantage of in current layer-based approaches. Extending path planning to include these NGA techniques requires a new way to represent and organize contours which considers not only the generated paths, but also the associated vectors. This presentation presents a framework for the organization and implementation of a generic representation of additive manufacturing build instructions, especially for use in non-planar and NGA build schemes. This framework is used to generate tool paths for several complex geometries, which contain features that can only be achieved using NGA welding techniques. The framework can also be modified to include algorithms that operate on varying levels of the part, from different types of segment algorighms to the individual waypoints for the final g-code generation. The implementation of this framework is shown on a variety of different geometries, and example cases of algorithms used for organizing and planning segments.</p>

Flexible Trajectory Planning Framework for Large Scale Additive Manufacturing of Metals

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.