| Abstract Scope |
The National Aeronautics and Space Administration’s (NASA) George C. Marshall Space Flight Center (MSFC) is partnering with The University of Tennessee in development of large aerospace structures via robotically controlled wire arc additive manufacturing (WAAM) in Aluminum 2319. Recent objectives include fabrication of thin-wall and bulk geometries in both gravity and non-gravity aligned (NGA) configurations. Demonstration of these structures encompassed welding process parameter development via pulsed gas metal arc welding (GMAW) for the base layer and cold metal transfer (CMT) deposition for all subsequent layers. Test beads were deposited and adjusted to determine proper voltage, current, wire feed speed, contact-to-workpiece-distance and robot travel speed. Experiments were conducted to compare between three path profiles: single pass thin walls, triple pass bulk walls and weaved bulk walls. Samples from each experiment have been evaluated using tensile testing and microstructure characterization. NGA robot trajectories have been created for exterior contour paths, overlapping beads and curved corners for bulk structures to mitigate out-of-plane gravitational forces on the weld bead. Performance of the welding torch, i.e., torch tip position, orientation, arc current, arc voltage and wire feed speed, have also been captured using a LabView based data acquisition system. |