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This paper describes coordinate system definition and transfer for five-axis machining of additively-manufactured preforms. In this method, a set of fiducials are attached to the temporarily attached to the part, and their location relative to the preform geometry is calibrated using a structured light scanner. Those fiducials can then be measured in the machine tool to determine the location and orientation of the part. The method is demonstrated by finish-machining a carbon fiber layup mold from an additively manufactured Invar preform. In addition to showing the coordinate transfer methods necessary to machine the part, several key challenges with machining additively-manufactured preforms are discussed and potential solutions are proposed. Unfortunately, the final part was ultimately unusable due to porosity inside the part left from the additive process. Future work will remanufacture this part while taking steps to avoid porosity and other challenges encountered. 

One of the most difficult aspects of printing large, complex metal parts is building large overhangs without the use of support structures. When using typical gas metal arc welding techniques, the torch is kept aligned with the gravitational direction. It has been shown that the maximum overhang angle that can be achieved is roughly 25°. This maximum can be increased by using part positioner, but this adds extra system complexity, especially for creating the robot paths. It is desirable then to develop a method of printing with the torch in a Non-Gravity Aligned (NGA) direction, such that the weld pool is supported and will produce the desired weld bead. This work focuses on the development of a control scheme based on sensor feedback of the state of the weld pool to maintain a stable, desired weld pool shape and thus print more complex parts using the gas metal arc welding process. 

The purpose of this research is to provide a framework for Large Scale Additive Metals Manufacturing (LSAMM) in arbitrary directions. Traditionally, slicing and path planning is done along the gravity aligned direction of a part, causing more complex geometrical shapes to have unsupported overhangs. The overhangs can be managed using a part positioner or a powder bed process. A different framework for slicing and building parts out of gravity alignment could improve current capabilities of LSAMM processes. The presented research focuses on segmenting more complex geometrical parts into gravity aligned (GA), non-gravity aligned (NGA), and transition segments to help generate toolpaths. Initial research of segment planning for complex geometrical shapes will be presented, as well as current results from builds completed at the University of Tennessee- Knoxville. The completed builds show that more consistent thermal evolution of a part based on the path sequence and torch angle results in successful builds.