Friction Stir Welding                                                  

	Friction Stir Welding
	Friction Stir Welding is a solid state joining process, in which a cylindrical shouldered tool with a profiled pin is inserted into the joint line between two pieces of material. Frictional heat is created between the wear resistant pin and the two work pieces, which are butted together and clamped onto a backing bar.
	The heat causes the materials to soften, without reaching melting point, and allows the pin to traverse along the joint. As the tool moves along, the material is plasticised by the frictional heat at the front of the rotating pin and transported to the back. Here it consolidates and cools down to form a solid state weld.
Advantages
Low distortion, even in long welds Excellent mechanical properties Low shrinkage Some tolerance to imperfect weld preparation (thin oxide layers) Welding Preparation not usually required Non-consumable tool Welding of wrought materials to castings No spatter No filler wire required No welder certification required Energy efficient Post weld processes not required No porosity