TWI

To overcome the limitations associated with conventional friction stir welding, particularly for complex shaped large structures, the bobbin tool technique was developed and demonstrated on various aluminium alloys (4-15 mm thickness range), the technological benefits of the process were assessed, and the mechanical properties of bobbin tool and conventional friction stir welds were compared. Bobbin tool feasibility trials were conducted on the following Al alloys: 2024 T3 and 6056 T4 (4 mm thickness); 2219 T87 (8 mm thickness); and 7449 TAF (15 mm thickness). Improvements compared to the conventional process were noted including: small vertical forces remaining within the welding head; no backing bar required; and fully penetrated welds with no chance of root flaw.

5th International Symposium, 14-16 Sep 2004, Session 1: Process Development, Paper 01