Using Non-Gravity Aligned Welding in Large Scale Additive Metals Manufacturing for Building Complex Parts

Penney, J.J.
Hamel, W.R.
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University of Texas at Austin

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.