What is an aluminium Extrusion – The process in 8 steps

It might be hard to believe but the process of aluminium extrusion has been around since the early 1900s. Incorporating aluminium extrusions into the design and construction of residential & commercial buildings, led to significant changes in the construction industry.

Aluminium is all around us, from aluminium windows and doors to the cans of soft drink we consume every day. Today we will learn more about aluminium extrusion and the process of how they are manufactured.

What is aluminium extrusion?
Aluminium extrusion is the process used to extrude aluminium alloy into objects or shapes that can be used in a variety of applications.

The extrusion process exploits aluminium’s unique combination of physical characteristics.
The metal’s malleability makes it easy to machine and cast, while its weight is one third the weight of steel but provides the same amount of strength and stability.

How does aluminium extrusion work?
The process consists of aluminium alloy being forced through a die with a special cross section profile. Once it has been pushed through the die, it comes out in the shape of the die opening – to extrude different types of aluminium extrusion, you only need to change the die opening.

Some people compare the process of aluminium extrusion to the force applied when squeezing a tube of toothpaste, with the opening of the toothpaste serving as the extrusion die.

Common Extrusion Shapes
Many different kinds of shapes can be manufactured with the help of the extrusion process. The most common ones are angles, channels, squares and round tubes. Aluminium extrusions can also be solid, hollow and semi-hollow.


The Aluminium extrusion process with Darley’s Mill Sales division
Aluminium extrusions are something Darley knows allot about – our Mill Sales division designs and manufactures customised aluminium extrusions.

Raw Materials
The aluminium extrusion process starts with raw materials. Bauxite is the world’s primary source of aluminium. The ore is chemically processed to extract alumina, which is then smelted using an electrolysis process to produce extrusion ingots. The highest quality raw materials are used to ensure quality and strength of the products we extrude.

Extrusion Ingots
The second step in the process is getting started with the production of extrusion ingot.
These ingots can be used for a variety of purposes. They are usually produced in factories.

Extrusion Die
Extrusion dies are large, flat disks with one or more openings, that allow you to create the desired cross sectional profile. Typically, they are made of H-13 die steel and heat treated to withstand the pressure and heat of hot aluminium begin pressed through the die.

Extrusion process
This is the step where all the magic happens. The ingot is heated and pushed through the aluminium extrusion die with a powerful ram that applies extreme pressure. It emerges from the die opening in the shape of the cross-sectional profile.

Surface Finishing
Once the aluminium has been extruded and left to cool down, you can then apply a surface finish, such as clear anodising, powdercoating or sublimation to enhance its appearance.  Or if you want to go with something more natural, you can choose mill finish – which is the natural appearance of aluminium after its extruded.

Value Added Services
Darley’s Mill sales division offers a number of value added services, in addition to the design and manufacture of customised aluminium extrusions – these include powdercoating, anodising, as well as light fabrication in the form of cutting or punching.

Packaging and shipping
Last step in the process is packaging the customised extrusions in bundles or secure crates and distributing them to any location within Australia.
To find out more about our Mill Sales division contact your Account Manager or your local Darley branch.


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