During aluminum extrusion, manufacturers transform aluminum alloys into definitive cross-sectional profiles and shapes, such as aluminum channels, aluminum extruded tubing, aluminum angles, and aluminum profiles.
These shape products are used to create more specific products, like: poles, window frames, quarter panels, running boards, car frames and bumpers, construction equipment, load-bearing ceiling beams, decorative trim, paneling and more. Extruded aluminum shapes can also be used as heating or cooling elements of heaters and refrigerators.
Different Types of Aluminum Extrusions and Their uses
Aluminum angles are standard extruded L-shaped parts composed of two legs that intersect and form a 90-degree angle.
Aluminum beams are used are structural and support components of building construction.
Aluminum channels are smooth, linear and fairly narrow channels that provide a supportive frame for roll-formed products.
Aluminum extruded tubing is a hollow, linear aluminum product. It is typically cylindrical, but it can also be square or rectangular. Aluminum square tubing and aluminum rectangular tubing are manufactured for specialty applications like aluminum downspouts and building supplies.
Aluminum frames are components of modular framing systems (constructed out of many different units).
Aluminum trim is long, thin and narrow. It can be custom made to fit a specific purpose or space.
Architectural aluminum may be used as both decorative and structural components of building construction.
Structural aluminum is an extruded aluminum alloy that goes through post-forming treatments in order to make it lightweight and durable. This corrosion resistant metal is used in many different high-strength applications.
Heatsink is a metallic device that absorbs thermal energy, or heat, from another object.
T-slotted aluminum extrusions can be used to construct almost anything, but are most often seen in: enclosures, cabinets, shelving, machine guarding systems, industrial workstations, office partitions, computer server racks, trade show exhibits, material handling and robotics.
The first metal extrusion process was patented by Joseph Bramah in 1797. Bramah was a prominent inventor and locksmith of the Industrial Revolution. He invented the metal extrusion process with the assistance of blacksmith Henry Maudslay. Their original goal was to perfect an impregnable lock. What they came up with was the process of hand driving soft metal through a mold, using a plunger in order to create lock parts. However, Bramah soon found that he could create other parts this way. In particular, he discovered he could use this method to create make soft metal pipe.
In 1820, Thomas Burr used the hydraulic press, also invented by Bramah, and the extrusion process to form lead pipes and rods. As manufacturers discovered that they could extrude other materials, the use of the process spread and advanced. Still, they shied away from aluminum. This is because, though aluminum is an extremely abundant resource, it is rarely found in its pure form and has to be extracted. Throughout most of the 1800s, raw aluminum extraction was difficult and costly.
This changed in the 1886, when Paul Heroult and Charles Martin Hall (independently from one another) developed a smelting process that involves electrolysis. This process, now known as the Hall-Heroult process, made aluminum much easier to extract. As a result, aluminum costs plummeted and it suddenly became a viable extrusion material option. In 1888, Karl Josef Bayer developed the Bayer process, which is a means to refine bauxite ore into alumina (aluminum oxide). This made it even easier to produce aluminum suitable for extrusion. Both methods are still used today.
In 1894, Alexander Dick invented the modern hot extrusion process, which allowed manufacturers to extrude non-ferrous alloys.
The first extrusion press was built in 1904 in Pennsylvania. This lead to a rapid development of the burgeoning aviation and automotive industries, which found extruded aluminum profiles to be quite useful. Then, in 1910, Robert Victor Neher of Switzerland patented the aluminum rolling machine. The aluminum rolling machine allowed manufacturers to mass produce thin aluminum foil for the first time. The foil proved very useful in the household.
In 1933, the American Congress passed the National Industrial Recovery Act (NIRA), which required all industries to establish safety and standard codes and guidelines for fair competition. This led to the development of the Aluminum Association, which held its first meeting in New York in 1935. They were essential in guiding the role aluminum and aluminum extrusion would play in World War II. During WWII, manufacturers used extruded aluminum to create mess kits, ship hulls and airplane frames. Because aluminum is recyclable, Americans held “Aluminum for Defense” and tinfoil drives in support of the war effort. Often, organizers exchanged movie tickets for balls of used foil.
After WWII, the United States and its Cold War rival, the Soviet Union, turned their eyes towards space. Sputnik I, the first Soviet satellite, which was launched in 1957, was made up of aluminum alloys. Today, manufacturers still extrude aluminum alloys for spacecraft assembly.
Today, aluminum extrusions are as popular as ever. Fortunately, they are 100% recyclable. This fits in with the world’s overall focus on sustainability and environmental stewardship.
No surprise, manufacturers make aluminum extrusions with aluminum and aluminum alloys. Aluminum is strong and stable, yet it is one-third the density and stiffness of steel. Manufacturers alloy aluminum with other materials in order to supplement characteristics like strength.
Some of the most common aluminum alloys used during extrusion include those in the 1000 series, 6000 series and 7000 series.
1000 Series aluminum alloys are non-heat treatable and have low strength. They do, however, boast high electrical conductivity and high thermal conductivity.
6000 Series aluminum alloys are heat treatable and easy to extrude and weld. They are corrosion resistant (including in marine environments) and have medium to high strength. They are strong enough for most load bearing applications, and are used for this both on land and at sea.
Al 6060 is the most commonly used aluminum alloy for extrusion. It offers good formability, easy extrusion of complicated cross-sections and medium strength. It takes well to anodization. Most often, it’s used to create handrails, doors, window, lighting components, awnings and furniture components.
Al 6101 is almost identical to Al 6060, except that it is stronger. It is best for use with electrical applications that require high strength components.
Al 6063 is somewhat stronger than Al 6060, but is somewhat harder to extrude. This is especially true if the manufacturer wants to extrude something complex. Nevertheless, Al 6063 shares almost all the same applications as Al 6060.
Al 6005A is stronger than Al 6063, but it is more difficult to extrude. Also, it works well for protective applications, but it is not great for decorative finishing because its surface quality isn’t good enough.
Al 6082 is quite strong. It works best with fairly simple cross-section extrusions and it can be anodized. Most often, this aluminum alloy is used in load bearing structures in ships, buildings and transportation structures.
7000 Series aluminum alloys have the highest strength of these alloy groups. They are easy to weld and do not lose strength during machining as easily as 6000 series aluminums. Unfortunately, they aren’t as corrosion resistant or as easy to form as the 6000 series. However, aluminum extrusions manufacturers can amend this by adding manganese, zirconium or chromium. This alloy series is a common choice for bike frames, car parts, high speed boats and aircraft containers.
Al 7108 is the most commonly used 7000 series aluminum alloys. It offers good fatigue strength and high tensile strength. It can, however, succumb to stress corrosion if put under very high stress. Nevertheless, Al 7108 can be used for transportation and building applications.
To create aluminum extrusions, manufacturers use hot or cold extrusion. This is very similar to other types of metal extrusion.
Generally speaking, the aluminum extrusion process goes as follows:
1. To form raw aluminum into extrusion profiles or channels, manufacturers set up round stock aluminum called “billets” or “logs,” to be slowly pressed by a hydraulic ram through a die. This die is a hollow profile that forms the aluminum into an exact extruded shape that is predetermined by the manufacturer.
2. Once through, the new shape is allowed to cool.
3. Next, the extruded aluminum may undergo finishing, if need be. This can entail any number of processes, such as stretching (used after hot extrusion), anodizing, painting, cutting, deburring, powder coating or assembling.
Engineers use a functional approach to extrusion design, which relies on common sense. Rather than thinking about what shape the structure needs to be, an engineer will first think about what the piece needs to do. After determining the use of the structure, he or she will consider what shapes and materials provide that support and how the elements relate to one another in a 3D environment. Finally, using these considerations, the engineer will design the custom aluminum extrusion.
Aluminum extrusion equipment generally features: a ram, a die, a press and a drive. The configuration of the machinery depends on the type of extrusion for which it is made and its custom application. For example, direct extrusion machinery will feature a ram that moves and a stationary die, while indirect extrusion machinery will feature a stationary ram and a die that moves. In addition, depending on the application, the press can be horizontal or vertical, and the drive may be mechanical or hydraulic.
The most customizable feature of aluminum extrusion machinery is the die, which can be custom designed to create cross-sections for any application. Manufacturers typically use CNC machining to assist them in this endeavor.
Variations and Similar Processes
Direct extrusion holds the die firmly in place as the ram pushes the aluminum alloy through the small die opening. Coupled with hot extrusion, this is the most common aluminum extrusion process.
Indirect extrusion, on the other hand, holds the die in position as the hollow ram moves into the stationary billet from one end, forcing the metal to flow through the die. Indirect extrusion creates products that are quicker to cool and more weather resistant.
During cold extrusion, an aluminum billet is pressed through the die at or near room temperature, creating close-tolerance components that have high strength and a great surface that will require almost no finishing work. Cold extruded parts do not experience oxidation.
Warm extruding (also called forging) is done on billets brought to temperature ranges between 800 and 1800 degrees F, with the ideal ranges being between 1,000 and 1,330 degrees. These temperatures are kept below material recrystallization temperatures, enhancing the billets’ ductility while keeping the material solid at the same time. Warm extruded aluminum does not use as much ram force or energy because the aluminum is more malleable, and it may not even require further treatment.
Hot extrusion is used on aluminum that has been fully plasticized by heat. This is usually done in a vacuum to avoid damage from oxidation. This process is generally economical and versatile.
Because aluminum is so strong, resistant to corrosion, and tolerant of a wide range of temperatures, it’s often the first choice for many building projects or industrial applications. It’s also lightweight, 100% recyclable and relatively easy manipulate and fabricate. In addition, aluminum extrusions require comparably little machining, even when they are complex.
How to Choose the Right Manufacturer
If you’ve decided that aluminum extrusion is right for you, you now need to figure out who you want to create your extruded aluminum products. Since aluminum is so expensive, many manufacturers offer this service. Inevitably, some of these manufacturers are not as skilled or as honest as others. We don’t want you to end up with a bad manufacturer. To make sure you have a good experience, we’ve compiled a list of highly skilled extrusion companies. You’ll find the details of these manufacturers sandwiched between these information paragraphs. We recommend you spend some time studying these profiles, keeping mind all of your specifications, including your budget, project timeline, standard requirements, delivery preferences and post-delivery support requirements. Select three or four manufacturers that you think might best meet your needs. Then, reach out to each of them for a conversation or a quote. Compare and contrast the information you get, and pick the one for you. Good luck!