TWI Frequently asked questions
When making a lap joint with friction stir welding, the central probe of the rotating tool is pushed through the top sheet and a small distance into the bottom sheet. It is important that the components are adequatelyrestrained.
As with conventional friction stir welding, the rotating tool is traversed along the weld line. Frictional heat generated by the tool softens the material which is forced to the back of the tool where it consolidates to form a highquality solid phase weld. Tool design is very important, in order to prevent movement of the interface towards the plate surface close to the nugget region. Optimum tool designs generally differ from those used for butt welds.
Instead of using a conventional tool, a double-sided bobbin tool can be used.
Using friction stir welding, TWI has successfully lap welded aluminium alloys from 1.6 to 6mm thick. There are now many applications in use and under development.
