This process uses high rotational speed and the resulting frictional heat created from contact to crush, stir together and forge a bond between two metal alloys. The technique is reliable and maintains higher material properties than other methods. However, friction stir welding's drawback is reliance on the single-piece pin tool. When welding with a single-piece pin, a keyhold is left at the end of the weld. This can create problems when welding items such as drums, pipes and cylindrical storage tanks.
The tool Ding and Oelgoetz have patented has the capability to make complete, 360°, circular welds essential for cylindrical objects. As the device passes the original starting point, it slowly begins to retract the welding pin into the shoulder of the pin tool, rewelding at lesser and lesser depths until the keyhold is closed.
Friction stir welding currently is being implemented into manufacturing of the space shuttle's external tank. While the current technology is applicable mainly in the aerospace and aircraft airframe industries, its application in other fields is beginning to be explored.