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Friction stir - the way ahead

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

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Fig. 1. Engraved support plate showing mirror image

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 Whorl™ 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. 4. Basic variants of the Whorl™ tool



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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 Whorl™ configuration can be altered to suit different materials by changing the inclination of the continuous spiral ridge.

Whorl™ is a trademark of TWI.

For more information on new developments in friction stir welding, contact Wayne Thomas, Peter Fielding, Dave Nicholas or Peter Temple-Smith. E-mail: wayne.thomas@twi.co.uk