Friction Stir Welding

Press release: Friction stir welding – enabling worldwide engineering success (1st Nov 2012)

Friction Stir Welding was invented by Wayne Thomas at TWI Ltd in 1991 and overcomes many of the problems associated with traditional joining techniques. Friction Stir Welding is a solid state process which produces welds of high quality in difficult to weld materials such as aluminium and is fast becoming the process of choice for manufacturing light weight transport structures such as boats, trains and aeroplanes.

Fabricators are under increasing pressure to produce stronger and lighter products whilst using less energy, less environmentally harmful materials, at lower cost and more quickly than ever before. Friction Stir Welding, being a solid state, low energy input, repeatable mechanical process capable of producing very high strength welds in a wide range of materials, offers a potentially lower cost, environmentally benign solution to these challenges.

Friction Stir Welding was invented and pioneered by TWI Ltd and therefore we have a wide range of experience of applying the process industrially in addition to in-depth knowledge of the fundamental science underlying the process.

The process advantages result from the fact that the Friction Stir Welding process takes place in the solid phase below the melting point of the materials to be joined. The benefits include the ability to join materials that are difficult to fusion weld, for example, 2XXX and 7XXX aluminium alloys, magnesium and copper. Friction stir welding can use purpose-designed equipment or modified existing machine tool technology. The process is also suitable for automation and is adaptable for robot use. Other advantages are as follows:

• Low distortion and shrinkage, even in long welds

• Excellent mechanical properties in fatigue, tensile and bend tests

• No arc or fumes

• No porosity

• No spatter

• Can operate in all positions

• Energy efficient

• One tool can typically be used for up to 1000m of weld length in 6XXX series aluminium alloys

• No filler wire required

• No gas shielding for welding aluminium

• Some tolerance to imperfect weld preparations - thin oxide layers can be accepted

• No grinding, brushing or pickling required in mass production

• Can weld aluminium and copper of >75mm thickness in one pass.