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Aluminium  Extrusion and Aluminium Profiles

Aluminium Processes

The Aluminium Extrusion Process Direct Extrusion Indirect Extrusion

Aluminium Extrusion is a plastic deformation process of a pre-heated aluminium billet which is then forced to flow, by compression, through a steel or ceramic die with an aperture of a smaller cross-sectional area than the original billet.

This extrusion process can be used to produce a wide variety of solid, hollow sections and profiles produced by extrusion through various style dies.

Seamless tubes and seamless hollows sections must be produced using either hollow billets or solid billets using a piercing press and mandrel system.

In direct aluminium extrusion process the preheated billet , or aluminium bar, is placed in the heated part of a press called the container. Here, the billet is pushed through the die by rammed pressure. The direction of the metal flow is the same as that of the the ram travel. During this process, the billet slides relative to the walls of the container, resulting in a necessary increase in ram pressure to overcome the friction between the billet surface and container liner.

Not all the aluminium billet is extruded. A percentage of the compressed billet, called the discard is left at the end of the extrusion cycle. This is ejected from the press during its dead cycle operation, and recycled at a later date.
With indirect aluminium extrusion, the die located at the front end of a hollow stem moves relative to the container. The die is either pushed through the container or the container is pushed over the die. There is no relative displacement between the billet and the container liner. Therefore one advantage of the indirect extrusion process is that there is no friction, during the process, between the billet and the container liner. The metal flow is more uniform during indirect extrusion than direct. This usually relates to better section uniformity along its length. As with the direct extrusion process a percentage of the billet is left over as discard. This aluminium is also once again recycled.
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