Ultra-High Speed Friction Stir Lap Welding of Aluminum Alloys

Historically friction stir welding has been viewed as a welding process that improves quality at the cost of complicated setups and slower welding speeds. Friction Stir Lap Welding (FSLW) has been shown in literature to be effective at linear speeds up to 1.5m/min, above which a hooking defect begins to deteriorate weld quality. While little investigation has been reported about increasing the linear speed of FSLW, numerous studies have demonstrated that traditional friction stir welding in butt configurations have been successful at speeds up to 6m/min. In order to increase the linear speeds of FSLW, a polycrystalline diamond tool using a multi-shoulder tool geometry was introduced to eliminate both the hooking defect reported at lower speeds and to enable higher rotational velocities of the tool. This novel approach enabled an order of magnitude increase in welding speed, which was defined as ultra-high speed FSLW at speeds of 10m/min and higher. Using Mazak’s CNC platform with an integrated friction stir welding controller, a evaluation of welding was completed to demonstrate weld quality at these speeds. Characterization of the welds including both static and dynamic testing was completed to demonstrate that FSLW at 10m/min and faster can be used for assembly without any deleterious influence from this significant increase in productivity.