What is extruded aluminum?
A recent forecast by Technavio, a global market research company, states that the aluminum market has potential to grow by 6.76 million tons in the years between 2020 and 2024.
We come across aluminum extruded profiles almost every day but we do not know it. As a matter of fact, aluminum is employed in several sectors - for instance, we see it in door or drawer handles, in window frames, in handrails etc.
But where do aluminum extrusions come from? And how does aluminum extrusion work? Discover it in this page:
- What is aluminum extrusion?
- How is it made?
- Custom aluminum extrusions
- Aluminum tiniest dimensional tolerances
- Aluminum alloys
- What are aluminum extrusions used for?
What is aluminum extrusion?
Aluminum extrusion is a process used to transform aluminum alloy into objects by forcing the material through a die with a specific cross-sectional profile. Aluminum’s malleability allows it to be easily machined and cast; at the same time, being one-third the density of steel, the resulting objects are characterized by remarkable strength and stability.
During the extrusion process, a ram pushes the aluminum through the die and it emerges from the die opening in the same shape as the die. It is then pulled out along a runout table.
The resulting shapes can be either simple or complex depending on the die shape, and can also have very tiny dimensional tolerances, like those Profall is able to achieve. In fact, a variety of aluminum profiles and objects can come out of the extrusion process. We can divide them into three main categories:
- Solid, with no enclosed voids or openings like round tubes, beams, and angles
- Hollow, with one or more voids such as square or rectangular tubes
- Semi-hollow, with a partially enclosed void like C-channels
To get a better idea on what you can obtain from aluminum extrusion, take a look at our Aluminum Extrusion Catalog.
Whichever extruded profile you need, choose Profall: we ship worldwide!
How does aluminum extrusion work?
The following ten steps briefly explain how aluminum is extruded from the moment we design the die until extrusions are moved to the saw table.
#1 Designing and manufacturing the die
The first step consists of designing the die for extrusion and making it from H13 steel. Before extrusion, it is preheated to between 450°C and 500°C: it is a way to maximize its life and ensure metal flow.
It is now the moment to load it into the extrusion press.
#2 Preheating a cylindrical aluminum billet
A solid, cylindrical billet is cut from a log of aluminum alloy, and preheated in an oven between 400°C-500°C. The preheating step makes it malleable enough to undergo the extrusion process, but not molten.
#3 Transferring the billet to the press
A lubricant or release agent is applied on the surface of the aluminum billet and to the extrusion ram to prevent them from sticking together. The billet is now mechanically pushed to the extrusion press.
#4 Pushing the billet into a container
The hydraulic press applies up to 15,000 tons of pressure on the aluminum billet, which is pushed into the container of the extrusion press, expanding in such a way to fill the walls of the container.
#5 Obtaining the extruded profile
A continual pressure is applied to the billet, which now goes out through the openings in the die: it emerges in the shape of a fully-formed aluminum profile. To avoid the formation of oxides, nitrogen in liquid or gaseous form is introduced through the sections of the die. This creates an inert atmosphere and increases the life of the die.
#6 Cooling the extruded profile
To be made, the extruded aluminum profile needs to pass onto a run-out table and be uniformly cooled by a water bath or by fans above the table.
#7 Shearing the aluminum profile to table length
Once the profile reaches its full table length, it is sheared by a hot saw to separate it from the extrusion process. At this point, the extruded profile has not yet fully cooled.
#8 Cooling aluminum to room temperature
It is now time to transfer table-length extrusions to a cooling table, where fans cool the newly created aluminum extrusion. It will stay here until it reaches room temperature.
#9 Stretching into alignment
During the cooling process, it may occur that aluminum extrusions undergo some natural twisting which, of course, need to be corrected. So, they are moved to a stretcher for straightening and work hardening.
#10 Cutting extrusions to length
The hardened extrusions are brought to the saw table and cut to the required length.
#11 Heating aluminum inside an age oven
You may think that now extruded aluminum profiles are fully made. Not yet. As a matter of fact, the very last step of the extrusion process consists of treating the aluminum with heat inside an age oven that hardens the material while speeding up the aging process.
In the oven, aluminum profiles are usually aged until T5 or T6 temper. This is necessary to improve its mechanical properties such as tensile strength and yield stress.
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How we make custom aluminum extrusions
Additional complexities may be applied during the extrusion process to customize the extruded parts. For example, to create hollow sections, pins or piercing mandrels are placed inside the die.
Depending on the final use of the extrusion you require, you may also need some surface finishing to adjust the color, texture and brightness of the aluminum’s finish or to make it resistant to rust and corrosion.
We can divide surface finishing treatments into three main categories:
- Punching, drilling, cutting etc.
Anodisation is a galvanic, or electrochemical, process that aims to create a layer of oxide on the surface of the extrusion. The final purpose is to improve aluminum’s resistance to corrosion caused by atmospheric agents or rust by improving surface emissivity. In addition, the layer of oxide makes the surface porous so that it can accept various colored dyes - from neutral tone to bronze shades ranging from light champagne to dark.
If you have specific aesthetic requirements, powder coating is the solution as it applies a layer of colored material upon the extrusion surface. It is commonly an epoxy or electrostatic polyester powder coating that adheres to the surface, which needs to undergo a secondary treatment to render the coating layer uniform.
Profall makes coated extrusions in all the RAL colors - including special aesthetic effects such as wood-like textures.
Punching, drilling, cutting aluminum
These are just three of the many available options that allow us to create a piece of extruded aluminum of the exact dimensions and specifications you need.
For instance, we can drill screw holes into a structural piece or cross machine fins to obtain a specific pin design.
Other mechanical and finishing processes include:
- Shearing through a state-of-the-art software to transform the various profiles and match your needs
- Aluminum packaging, with the chance of applying logos, bar codes and specific IDs
The tiniest dimensions on the aluminum market
Customization is really Profall flagship. Getting a bit into details, it means that:
- You can choose among standard or special profiles in our catalog, and ask for customization
- You can contact us to make fully tailor-made aluminum extrusions
The most part of the requests we receive is focused on the production of extruded aluminum pieces with extremely tiny dimensional tolerances, which are quite hard to find on the common aluminum market. For instance, tubes have standard dimensional tolerances of +/- 0.15 mm per side, but we can produce them also with smaller dimensions and all the mechanical characteristics and complexities you need.
The choice of which alloy to use is directly depending on the final use of the extruded profiles and their mechanical features. At Profall we basically extrude aluminum of three different alloys:
- 1000 series with a minimum purity rating of 99.5% - these alloys have high electrical and thermal conductivity properties, and are extremely resistant to corrosion
- 3000 series alloys are mainly made of Manganese - extremely resistant to corrosion, this series of alloys is mainly used in automotive applications and for braze welding purposes
- 6000 series, which contains Silicium and Magnesium, is easily processed and welded - one of the most used alloy is the 6063 aluminum, employed to manufacture square, rectangular and round bars and tubes.
What are aluminum extrusions used for?
Aluminum extrusions have several applications across various sectors, such as:
- Construction - Elevator shafts and stairwells are all made from extruded aluminum which, in addition, is also used to aid the structure of the interior of the building.
- Automotive - Aluminum resists the long-term environmental effects of temperature, moisture, and the corrosiveness coming: as such it is used to make the body, frame components, radiator enclosures, drive shafts and cylinder liners
- Electrical sector and electronics - Due to its non-magnetic, electrical and thermal conductivity, extruded aluminum is also used for producing electronic chassis, racks and housings, power units, computer cases and the likes
- Energy - Having high electrical conductivity which is quite two times that of copper on an equal weight basis, aluminum also takes part in the construction on alternative energy generation and distribution systems, such as solar panels
- Lightning - Aluminum LED totem, lamps fixtures offer remarkable benefits in terms of energy saving and production costs. In addition, thei extrusion dissipates the heat generated by the lighting elements themselves.
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