NASA Marshall Space Flight Center has successfully commercialized a welding technology called retractable pin tool for friction stir welding (FSW). MTS Systems Corp. and MCE Technologies Inc., under license from NASA, have introduced products that use NASA’s FSW process improvements.

Introduced and patented by The Welding Institute in the U.K., FSW has been widely recognized for its ability to provide greatly improved weld properties over conventional fusion welds. During the FSW process, the pin of a shouldered tool slowly plunges into the joint between the two materials and rotates at high speed. The resulting friction creates a plasticized shaft of material around the pin. As the pin moves forward in the joint, it "stirs," or crushes, the plasticized material, creating a forged bond, or weld.

However, there were two major drawbacks with the initial design: different length pin tools were needed when welding materials varied in thickness, and the pin tool left a keyhole at the end of the weld. Marshall’s FSW process created an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. Marshall’s technology allows the pin angle and length to adjust for changes in material thickness and results in a smooth hole closure at the end of the weld.

MTS Systems, a supplier of mechanical testing and simulation equipment, just introduced an advanced friction stir welding process development system for automotive, ship building, and other industries. MTS Systems’ product enables advanced FSW applications for high-strength structural alloys. A high-force, self-contained design includes a multiaxis weld-head manipulation system and a custom head assembly that incorporates the retractable pin tool.

MCE Technologies, which provides engineering and manufacturing services and equipment, developed a line of stir welding products that provides flawless welds in virtually all FSW applications using high-performance aluminum alloys, including those previously considered unweldable, the company said. IT