Friction stir welding （FSW）
Friction stir welding (FSW) was developed in 1990, based on the principle that two separate metals can be stirred/welded together in plastic form with frictional heat, without a need for added heat or added filler material, this technique is licensed in the UK. Some features of FSW are shown below.
1. Increased strength
2. Increased protection against leaks – entirely void-free, impermeable joints of a higher strength than fusion welded joints
3. Joints that are, in principle, flush with the surface
4. Reduced thermal deformation – only low thermal stress in the material, hence the flat surface
5. Increased repeatability – production has few variables and these are easily controlled; the result is tight tolerance
As one of the companies who developed this process, Sapa has so far the most experience in its application. Sapa Extrusion Shanghai had introduced this process from the very beginning. More than 50 percent of our products are today made with the utilization of FSW. With FSW, we can exceed the limitation of the extrusion process “limited sectional size” and make section wider than 600mm, thereby offering excellent solutions to customers interested in large-sized heat sinks, floors for trains and ships, and more.