Sapa Friction Stir Welding

Welding was never so perfect

In contrast to the more commonly used fusion welding, Sapa uses the advanced friction stir welding (FSW) process to join aluminium profiles.

FSW utilises the ability of aluminium to withstand a large amount of plastic deformation at high temperatures below its melting point. The bare metal surfaces of the profiles to be joined are heated by the friction of a rotating tool and joined together mechanically at very high pressure.

This process results in the formation of a new, homogenous structure. It does not require a filler material or a protective atmosphere. FSW results in an excellent, pore-free weld seam without any inclusions.

Benefits of friction stir welding vs. fusion welding:

enhanced tightness due to completely pore-free, higher strength, impermeable joints

joints that are always flush with the surface

thermal stresses in the material that are only small (less thermal distortion)

improved repeatability as a result of tight tolerances

FSW is an advanced technology developed by The Welding Institute in Cambridge, England. Sapa actively supported the development work from the initial idea and laboratory experiments through to its use on a production scale.

Sapa has been using FSW in series production since 1996 and now supplies FSW-joined panels up to a width of 3.00 metres and a length of 14.30 metres.

The FSW process is very popular and is being used in increasingly more sectors. Following extensive testing, FSW is now approved, for example, for use in rail-vehicle manufacture and shipbuilding