Friction Stir Welding (FSW) is a solid state joining process invented at TWI (The Welding Institute, Cambridge, United Kingdom) in 1991. TWI filed for world-wide patent protection in that December (Patent No.: PCT/GB92/02203). In the same year, the State Intellectual Property Office of P.R.C accepted the patent application for FSW and FSW tools from TWI (Patent No.: ZL 95 1 92193.2).
Friction Stir Welding (FSW) is an innovative solid-state joining technology which was invented at TWI (The Welding Institute, Cambridge, United Kingdom) in 1991. During the welding process, a non-consumable rotating tool with specially designed shoulder and pin is plunged into the joint between the workpieces and traverses through the joint line while the shoulder is in intimate contact with the top surface of the workpiece to avoid expelling plasticizing metal for frictional heat, with the function of the tool force, the workpieces join together.
FSW Process Principle (from TWI)
Technical features of FSW:
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Mechanized welding process and easy operation
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No special preweld preparation
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Nearly zero-distortion
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No shielding gas or filler material required
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Low energy consumption and high welding efficiency
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Environmental friendly without fume, spatter, UV or electromagnetic radiation
Friction Plug Welding (FPW) --- repair welding for FSW Key-hole Releasing
Friction Plug Welding (FPW) is a solid-state welding technology firstly invented by TWI, which adopts special consumable stopper to release the FSW key holes and to repair defects, under certain pressure or tension, the actuating device drives the very stopper to rotate, and the friction between stopper and plug socket can thus be generated, while the metal of stopper is in plasticizing state, with dwell pressure for a certain period, the welding process ends. This technology can also be used for the narrow gap welding in heavy section.
The FPW Technology is as a fast, environmental friendly welding method with very low cost, usually, it takes 20s to weld a hole with depth 100mm, and it also works in mal-condition.
CFSWC has already successfully developed FPW technology through plenty of research and experiment work, till now it has been applied for the defect repair, FSW key-hole release, etc.
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