Aluminium Extrusion – Everything you need to know
Extruded aluminium can be formed into any shape or size. It’s so popular and versatile that around half of all the aluminium we process and ship is extruded. If you’re after round bar, square bar, flat bar, or hexagonal bar aluminium, they’ve all been extruded. Here are answers to some of the most widely-asked extruded aluminium questions.
What is extruded aluminium?
Think pasta! Extruding aluminium is similar to hand-made pasta. You place the metal in a special press. It gets pushed through the cut-out die you’ve chosen or created. Then it comes out of the other end in the shape of the die. The technique is used to transform everyday aluminium alloy into objects with a defined cross-section, created for specific uses. The extrusion process itself taps into the metal’s unique characteristics.
How is aluminium extruded?
First you design the die in the shape you want to extrude the metal. Then you heat a cylinder of aluminium alloy to 800°F-925°F before transferring it to a loader and adding a lubricant to stop it sticking to the extruder machine or anything else. A great deal of pressure is then applied to a dummy block using something called a ram, which rams the aluminium into the container and onwards through the die.
We don’t want oxides to form, so we let liquid nitrogen – or nitrogen gas – flow through the die to create an safe, inert atmosphere that also boosts the lifespan of the die itself. The extruded metal is the same shape as the opening in the die, and that your ‘extrusion’.
When the metal has cooled down we can straighten and harden the extrusion, and cut it to the right length. Then we heat it all over again to speed up the hardening process. If we need to create something more complex, maybe customise the design, we can do clever stuff like make hollow sections, or add mandrels inside the die to make unusual profiles. Finally, we can change the colour, texture and brightness of the final item, and may even anodise or paint the surface.
Who invented aluminium extrusion?
The history of extrusion goes way back to 1797 when Joseph Bramah patented the first ever extrusion process, designed to make pipe from soft metals. In 1820 Thomas Burr used the same process to form lead piping, using a hydraulic press that was also invented by Bramah.
Why was aluminium extrusion invented?
Extrusion is a reliable way to make a huge variety of standard and unusual shapes for use in many sectors. Extruded aluminium alloys help manufacturers make parts with specific qualities. You might need aluminium parts to be particularly strong, or unusually resistant to corrosion, or have a very complex profile. Extrusion achieves all of this and more.
What purpose does extruded aluminium serve?
Aluminium itself is famously workable, and different die designs mean a multitude of profiles are possible. The metal is malleable but also strong, so is perfect for structural and mechanical projects. It resists rust and corrosion, simply oxidising a little to form a protective coating. Aluminium is 100% recyclable and can be recycled infinitely. It’s often surprisingly cost-effective and looks amazing. It conducts heat and electricity beautifully and weighs very little, roughly a third the weight of steel but equally strong.
In a nutshell, the purpose of extruded aluminium is to provide lightweight extra strength and resilience to an extraordinary variety of vital products and objects.
What are the common uses of extruded aluminium?
Aluminium’s high strength-to-weight ratio makes it ideal for cars, aircraft, bicycles, boats and trains. Light vehicles use less fuel, so using aluminium saves petrol. Its remarkable strength means vehicles made using it can carry much heavier loads.
Extruded aluminium is used to make attractive, rugged in-store and point-of-sale retail displays. It’s harnessed widely in the construction industry to make beautiful, durable panelling, lighting, and the many different types of extruded parts used to create facades.
The metal’s excellent conductivity – twice as good as copper – means it’s popular for power systems and mounting systems across many sectors. Military and defence are large consumers of extruded aluminium, used for anything from military vehicles to landing mats and temporary structures. And the extruded metal forms an essential part of the International Space Station, namely the tubing used for the trusses that link the different bits of the station together.
What affects the price and supply of extruded aluminium?
The price and supply of the metal itself affects the availability of extruded aluminium most of all. If we have aluminium, we can extrude it! The metal’s cost depends on many factors including the cost of electricity, vast amounts of which are needed to smelt the metal. If the cost of energy goes up, so does the price of aluminium.
New innovations also have an impact. Take air travel. Aircraft manufacturers are under massive pressure to invent planes that emit less CO2, and one way to do that is make them even lighter. The resulting aim to cut the amount of aluminium used in aircraft manufacture from 50% to 20% will have an impact on demand, therefore on the market as a whole.
The construction industry, another huge consumer of extruded aluminium, is volatile at the best of times and more so than ever before thanks to Covid-19. This affects supply and demand, which in turn impacts the price of the metal.
When we see low production stocks along with intense construction activity, high demand and low supply push prices up. The cost of the raw aluminium itself varies along with economic changes, fluctuating exchange rates, trade wars, political difficulties between nations, and cyclical recessions.
Only one thing is certain. As long as the metal is used by monster industries like construction, transport and the military, the cost of extruded aluminium will keep on fluctuating alongside them.
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