Aluminium extrusion suppliers – A quick guide to extrusion

By: Effective



You might have a close relationship with your aluminium extrusion suppliers. But do you know how the process works? It’s fascinating stuff. If you’ve ever wondered what goes on behind the scenes, here’s a potted version of the history, science and technology that lies behind the process. 


The secret behind aluminium extrusion suppliersproducts


First, what is extrusion? It’s the process of creating objects with fixed cross-section profiles, which involves pushing or drawing the material – in this case a metal - through a die, a 3D mould with the desired cross section. It’s a highly practical way to make extremely complicated cross-sections because the comprehensive and shear stresses and strains it involves are manageable, and the end result has an excellent surface finish. 


The history of extrusion


Go back through the mists of time to 1797 and you’ll find Joseph Bramah patenting the world’s first extrusion process, designed to create lead piping. He came up with a process that preheated the metal so it was easier to force it through a die using a simple hand-driven plunger. The process stayed much the same until two decades later when, in 1820, the inventive Thomas Burr built the world’s first hydraulic press and named the process ‘squirting’. Fast forward to 1894 and the talented Alexander Dick expanded the process so it worked with a wider range of alloys, including copper and brass. 


Different kinds of extrusion


As any good aluminium suppliers will tell you, extrusion can be continuous, creating an indefinite stream of material. Or it can be semi-continuous, creating multiple items.  


For hot or warm extrusion projects, the process starts with the material being heated before loading it into the press container. A dummy block is wedged behind it to push it out of the die. Then the extrusion is stretched to straighten it out. It can also be heat treated or worked cold to give it the required properties. 


Hot extrusion is carried out above the metal’s recrystallization temperature, to stop it hardening and make the actual extrusion easier. It usually involves a horizontal hydraulic press of anything from 230 to 11,000 metric tons, at pressures between 30 and 700 MPa, with oil, graphite or glass powder lubrication. Aluminium hot extrusion temperatures sit between 350 and 500 Centigrade.  


Cold extrusion works at room temperature. There’s no oxidation and the result is stronger simply because it has been worked cold. There’s usually a better surface finish and closer tolerances, as well as faster extrusion speeds when it’s subjected to hot shortness. 


Warm extrusion happens above room temperature but below recrystallization temperatures, somewhere between 424 to 975 Centigrade, resulting in an excellent balance of forces, ductility and extrusion properties.


Whatever your aluminium extrusion needs, make sure you identify a supplier who knows the ins and outs of the process intimately, people who know the importance of technical expertise, quality and keen pricing. 

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Metalex stocks an extensive range of Aluminium Plate, Aluminium Bar, Aluminium Extrusion, Brass, Steel, Stainless Steel, Alloy Steel, Cast Iron and Speciality Metals.   Contact us at [email protected] for more information.

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