Initially, the aluminium alloy is formed into billets by our on-site foundry. The billets are then heated in a furnace to achieve the required extruding temperature, 450-500° C. The billet is then loaded into a container, and squeezed through a die orifice using ram pressures of up to 680MPa.

As the extrusion passes through the press, friction between the metal and the die raises its temperature to between 520 and 540° C. Kaye Aluminium deals with heat treatable alloys, to which is applied a form of solution heat treatment known as quenching. This is to help achieve the various tempers that can be offered for the different alloys. (See section on HEAT TREATMENTS ),

After extrusion the section is guided on to a slatted moving belt by a puller. Modern pullers are based on linear motor systems and operate on tables up to 40 metres long. On completion of an extruded length, the section is sawn at the press end and lifted from the slatted table by eccentric pivoted arms. It is then transferred by a walking beam or multi-belt transfer table to the stretcher bay where it is given a controlled stretch to straighten and remove minor misalignments. The section is then cut to ordered lengths on high-speed tungsten carbide tipped saws.

If the material is required in the solution heat-treated T4 condition (see section on HEAT TREATMENTS ), the material is released at this stage. When the T5 temper is required, there is a limited cooling at the press exit, and the material goes directly into heat treatment (by solid-solution strengthening precipitation treatment). If the material is required in the full strength aged T6 condition, it is given a precipitation treatment before release.