Squeeze formed wheels are lighter and stronger

To make them, a forming tool is first loaded with molten aluminium alloy, after which a punch falls rapidly to the surface of the liquid metal and then follows the surface of alloy downwards as it solidifies and shrinks. This maintains pressure during solidification, producing a finer microstructure than would be the case if it were allowed to solidify under the effects of gravity alone. Mike Ridgway, commercial director of manufacturer GKN AutoStructures, said: "We believe this is a development with huge potential to extend the performance of the military vehicle. We have proved the process through extensive production and the operational life our AFV wheels are achieving is exceptional. We are keen now to work with current and potential customers to explore the many other possibilities across the military arena." As well as wheels, the same process is also used to create the fully weldable aluminium armour to protect the Warrior vehicle. It is particularly applicable to manufacturing structures with complex shapes, where fine control of the finished product is required or where there is a need to reinforce the structure in highly specific areas to provide additional, focused strength and/or flexibility. In addition to military applications, GKN Land Systems has identified market potential for the process for producing metal matrix composite structures for civilian automotive components such as brake calipers where the control, precision and quality offered by 'Squeezeform' combines with the high specific strength and stiffness, improved performance at higher temperatures and lower weight of MMC structures.