1st Paragraph: Self-reacting friction stir welding (SR-FSW) is the primary joining technique used in the construction of the core stage and upper stage of NASA’s Space Launch System (SLS) rocket . This process joins 2219-T87 panels using a rotating cylindrical pin tool and backing plate. As the pin tool moves along the circumference of the rocket, it creates a welded joint with lower residual stresses and distortion than traditional welding processes. One disadvantage of SR-FSW is that (relatively) small holes are created at initializing and termination points of the weld when the pin-tool assembly is inserted and removed from the parent material panel. The holes are drilled to 1.375” in diameter and must be repaired to seal pressurized liquids (liquid oxygen and liquid hydrogen) within the structure. The SLS engineering team is faced with a mission-critical challenge in finding a solution to repair these machined holes while maintaining the structural integrity of the rocket.
Authors: Kathryn Anderson, Steve Daniewicz, Paul Allison, and Robert Amaro
Keywords: Friction Pull-Plug, Additive Friction Stir Welding, Aluminum