Friction-stirWelding
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TWI and the super-thin iMac
The slim lines of the upcoming iMac models would be impossible if it weren't for a bit of intellectual property from Cambridge, England-based TWI. TWI developed a technique called friction-stir welding in 1991 that doesn't require melting metals to join them together. Through the use of a rotating tool made out of a wear-resistant material, metals are softened and then merged under frictional heat. The method has been used in the aerospace industry for years to produce rocket propellant tanks, airplane wings and is used at Denver's Lockheed Martin facilities on the manned Orion spacecraft. Friction-stir welding is now coming down to earth to join the aluminum front and back of the new iMacs, creating a welded edge that's only 5mm thick. Not only does the technique produce a smooth join, but the process is faster and uses less energy -- both important factors in the mass production of computers. Apple licensed the technology from TWI this year, although TWI could not reveal the details of the license or its application to existing or future products.
