J. Takeshita, W. Martin, Lockheed Martin, New Orleans, LA

Summary:

Lockheed Martin Space Systems Company- Michoud Operations has explored a variety of manufacturing approaches using friction stir welding and novel tooling concepts. Attention has been given to both the type of tooling used and the forces generated by the tooling to produce a good weld.

Two approaches to tooling have been used – the traditional, stalwart approach wherein clamping and support for the work piece are extremely rigid so as to prevent any movement of the part during welding. This rigidity and support is achieved by maximizing the clamping force. The second approach evaluates configurable tooling structures that employ minimal clamping and allow the majority of the work piece to rest on tooling without being rigidly held in contact. This tooling is being used on large-scale hardware. For example, 22-ft (8-m) arc lengths and domes with diameters exceeding 20-ft (7.3-m) have been successfully friction stir welded to date. The manufacturing trials employed a six axis machine with a moveable turntable. Metrics include time for set-up of the part, the amount that a part moves during welding, repeatability of the welds, and whether issues resulted from the tooling configuration.