An advanced friction stir welding tool has been developed by TWI that achieves an increase in travel speed of 150%. The new development was announced at the recent meeting on 'Friction stir welding of transport structures' held at the end of September.

Project sponsors welcomed the considerable increase in welding speed, which is achieved while maintaining or improving the existing high weld quality of the process.

Welding trials have been conducted on the normally difficult to weld aerospace Al-Zn alloy 7075-T7351. So far, a welding speed of more than 400mm per minute has been achieved when making butt joints in 6.35mm thick material. This represents an increase of at least 150% on the speed achievable with current commercially available friction stir welding tools. This tool also produces a higher weld nugget hardness, leading to higher tensile strength values. Even higher speeds are expected by changing the tool path about the axis of rotation. Trials are continuing