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Understanding the Aluminium Extrusion Process

Aluminium is a highly versatile material, but after going through the aluminium extrusion process it can take this versatility to new heights.

The extrusion process is, in its simplest terms, a relatively straightforward procedure: aluminium alloy is forced to flow through a cross-sectional die. The result is an elongated piece of aluminium which takes the fixed shape of the cross-sectional die. While this procedure may be simple to describe, and even execute, the science behind it is remarkable. And it’s a science which gives aluminium extrusions a number of benefits.

To help you understand how these benefits come about we’re going to take a closer look at the aluminium extrusion process.

The Aluminium Extrusion Process

There are a number of key moments during the aluminium extrusion process, but the most important ones are:

  1. A billet of aluminium is heated to around 800 – 925°F in order to increase its malleability for travelling through the extrusion process. This heated billet is then moved to a loader where a lubricant is applied to prevent the aluminium sticking to any part of the machinery. Both these steps ensure that the extrusion process can be completed without damaging the die.
  • The prepared aluminium is loaded into a cradle and, using a ram, is forced against the die. The aluminium gradually becomes shorter and wider before being pushed through the die. It’s at this point that liquid nitrogen is introduced to the die. The liquid nitrogen not only helps to protect the die, but the inert atmosphere it creates also prevents oxides forming on the aluminium.
  • The soft, but solid aluminium is forced through the die under incredible pressure and takes the shape of the required die. The only limit to the die’s shape is the creator’s imagination, so the range of available shapes is infinite. The extruded aluminium leaves the die as an elongated length and emerges onto a run out table.
  • The next step of the extrusion process is to pull the aluminium extrusion onto a cooling table where fans, or water, are used to rapidly reduce the temperature of the metal. This process starts to restore rigidity and increases its strength.
  • Following this cooling procedure, a stretcher is used to straighten the extrusion.
  • The extrusions are then cut to their required length on a saw table before being loaded into ageing  ovens to be heated. This heating process artificially ages the metal in a set amount of time . This ageing process re-aligns the molecules in the aluminium and this grants the extrusion an increased strength and hardness. And this is why aluminium extrusions are the perfect solution for so many load bearing projects.
  • The most important element of the aluminium extrusion process is the use of heat. The incorporation of heat is require before, during and after the aluminium travels through the die. The resulting extrusion is perfectly shaped, incredibly strong and has a clean finish which allows it to be used in almost any design project.

To see a video of the extrusion process click here : www.custom-profiles.com/aluminium-extrusions/extrusion-process

For more information on the extrusion process, don’t hesitate to get in touch.