What is aluminium extrusion?

Aluminium extrusion moulding is a kind of plastic processing method that applies strong pressure to the metal blank in the mould cavity (or cylinder), forces the metal blank to produce directional plastic deformation, and extrudes from the die hole, so as to obtain the required section shape and some mechanical properties of parts or semi-finished products.

To produce an aluminium extrusion, an aluminium billet (a solid block/log of aluminium) is preheated in an oven to between 400-500 degrees celsius. This makes it malleable enough for the extrusion process but not molten. It is then loaded into the container of the press and then forced through a shape created in a specially manufactured tool called a die. Once the aluminium has been pushed through the container by the ram within the press, it will form the extruded profile which will be the same shape as the opening(s) in the die.

The variety of shapes which can be extruded is almost endless, however, there are factors that put limits to what can be achieved. The factors which need to be considered include;

  • Size
  • Shape
  • Alloy – Chemical composition of other elements added to pure aluminium to enhance its properties such as strength, etc.
  • Extrusion Ratio - Area of the billet/area of the shape.
  • Tongue Ratio - Width of the gap vs. its depth.
  • Tolerance - Limits of variation in which a part or product can be produced to.
  • Finish – Treatments used to enhance the end look & feel of the profile.
  • Factor - Perimeter of Shape/ Weight per metre.

A profile that is designed beyond these limits may possibly not be extruded successfully.

All the above factors are interrelated in the extrusion process along with extrusion speed, the temperature of billet, extrusion pressure and the alloy being used for extrusion. These will all contribute to and determine the cost of your extrusion.

The speed of an extrusion varies depending on the temperature, pressure and alloy being used for the shape being extruded. (See selecting the right aluminium alloy for more information.)

The lower the temperature, the higher the pressure that’s required.  Lower temperature extrusions typically produce shapes that have a better surface quality and dimensions which are more accurate.

Higher billet temperatures and faster extrusion speeds mean metal flow becomes more fluid. The metal flow usually tends to fill the larger voids in the die face and resists trying to fill constricted areas. The shape's dimensions and tolerances are compromised using this method and often the profile is unsuccessful.

What are Aluminium Extrusions used for?

Aluminium extrusion is widely used in manufacturing to create parts with a constant cross-section. Aluminium extrusions are often used for:

  • Industrial applications
  • Architecture and Construction
  • Automotive
  • Signage and Lighting

Advantages of Custom Aluminium Extrusions?

✅ Complex cross-sectional parts
The main advantage of Aluminium extrusions is the ability to manufacture very complex cross-sections in varying lengths that are typically too difficult or impossible to produce via alternative manufacturing methods.

✅ Low to high-volume production
Once the die has been manufactured there is flexibility with order volume, both low and high volume extrusions can be produced economically. Whether you need a mass production or simply a one-off custom extrusion, this processing method has the capability and flexibility to deliver for any project.

✅ Tailor the mechanical performance
The strength of aluminium extrusions can be tailored by adjusting the wall thickness and internal structural profile of the extrusion. This means the strength can be concentrated precisely where it is needed without adding unnecessary extra material.

✅ Low-cost parts manufactured fast
Extruding is a very efficient process as parts can be manufactured continuously, making the cost per unit much lower compared to alternative manufacturing methods. Once the die has been manufactured, parts can be produced in a matter of days ready to be delivered, making extruding excellent for getting parts produced on demand.

✅ Excellent strength to weight ratio
Aluminium extrusions are lightweight (1/3 the weight of steel) and have a great strength to weight ratio. This makes them a popular choice for applications in the aerospace industry where weight reduction is a priority.

Disadvantages of Custom Aluminium Extrusions?

❌ Initial start-up costs
Although often not that high, there is an initial startup cost of manufacturing the extrusion die. However, this cost is quickly offset by the low cost of producing aluminium extrusions.

❌ Design constraints
Due to the nature of the extrusion process parts have to have a uniform cross-section. There are also some other design considerations that have to be taken into account.