What is the best way to weld Aluminium?

Welding aluminium is a much more complex operation than for other metals. Welding aluminium requires a great deal of skill and the right tools.
The best way to weld aluminium is by cold welding, or more precisely, by welding in the pasty state. Friction stir welding is an innovative cold joining process. FSW technology permits parts to be joined together by the application of pressure and friction without reaching the melting point.
This makes it an excellent way to weld aluminium without using heat. FSW also allows the mechanical properties of the material to be retained.