What are the different FSW weld types?

The most common types of friction stir welding are butt and lap welding.
The most usual FSW configuration is butt welding. The parts to be joined, of equal thickness, are placed against each other. In a lap weld, the two parts are placed on top of each other.
The choice of the type of FSW configuration depends on the materials to be welded and the geometry of the part. For example, only lap welding will allow the assembly of heterogeneous materials (aluminium/copper, aluminium/steel).
More details on these types of welding can be found in our article on the comparison between butt and through welding.