Materials joining specialist, TWI Ltd, has used equipment and expertise at its Yorkshire Technology Centre to make significant advances in welding technology. Friction Stir Welding, the novel joining process invented and developed at TWI, has been used to join two aluminium plates 75mm (three inches) thick in a single operation.
This is a phenomenal step change from the previous proven limit of 50mm, and a level deemed a distant objective when the process was invented in the early nineties. However, the latest development programme is still in its infancy, and TWI is confident that it can push the process's performance boundaries still further. TWI is already the leader in developing friction stir welding procedures for heavy section material, with one of the most significant projects relating to the sealing of copper canisters containing spent nuclear fuel for Swedish nuclear waste specialists, SKB. In this application, the canisters were 1m in diameter and had a wall thickness of 50mm.
The equipment on which the welds were produced is due to be moved to TWI Yorkshire's new facility at the Advanced Manufacturing Park, located between Sheffield and Rotherham. Here, the machine's capability will be extended by the addition of a second welding head located directly underneath the existing head, making it possible to weld components from two sides simultaneously. With current knowledge, this would enable single pass welds of 150mm thick material, but after that, who knows where the limits lie?
Jonathan Martin, Manager of TWI's Friction Stir Welding activities in Yorkshire, commented, "This is just the start of our explorations into the bounds of thick section friction stir welding with our new machine. We are looking forward to developing the many unique features of the machine, and extending the process's capabilities still further."
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