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Friction stir - the way ahead


Connect, January/February 1999

Identify yourself with FSW

In a recent refinement to friction stir welding, brand identification can now be self-embossed during the process. This is done by using an inversely engraved support plate (Fig. 1) carrying the required information - company name and logo for example. During the welding process, softened material is moulded into the mirror image (Fig. 2). This technique can be used for quality control as well by embossing datum witness marks at pre-selected intervals

Fig. 1. Engraved support plate showing mirror image
Fig. 1. Engraved support plate showing mirror image
Fig. 2. Self embossing during friction stir welding
Fig. 2. Self embossing during friction stir welding

Learning from nature - tool design for thick plate

Recent advances in friction stir welding (FSW) of thick plate have been made easier by TWI's development of a novel, rotating tool named the WhorlT taking its design from the natural world (Fig. 3). The basic variants of the tool are illustrated in Fig. 4. The seashell-shaped probe is machined with a progressively changing pitch and angled at a critical rake. This shape needs less effort to go through the plasticised workpiece than a conventional cylindrical tool.
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Fig. 3. This whorl type seashell shows progressively changing pitch and tapered shape
Fig. 3. This whorl type seashell shows progressively changing pitch and tapered shape
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Fig. 4. Basic variants of the WhorlT tool
Fig. 4. Basic variants of the WhorlT tool
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Fig. 5. A macrosection showing a double-sided butt weld in 6086 T6 aluminium alloy
Fig. 5. A macrosection showing a double-sided butt weld in 6086 T6 aluminium alloy

The effectiveness of this type of tool for thick plate welding is illustrated by a well-shaped weld profile in double-sided 50mm thick aluminium alloy (Fig. 5).

Additionally, the WhorlT configuration can be altered to suit different materials by changing the inclination of the continuous spiral ridge.

WhorlT is a trademark of TWI.

For more information on new developments in friction stir welding, Please contact us.

For more information please email:


contactus@twi.co.uk