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Aluminum Extrusion Sizes and Profiles

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Aluminum extrusion refers to heating aluminum metal until it reaches a pliable, soft state and then using a ram to push it through a shaped opening within a die. The result will be the creation of a particular cross-sectional profile. The openings in the dies can be modified depending on the shapes and sizes the user requires. Extrusion allows manufacturers to create extended lengths of aluminum tubing ranging from simple aluminum rods to extremely complex profile designs.


When users are deciding which profile design, size, and shape to order, they will consider multiple factors. To help us understand what makes aluminum such a popular choice and the variety of options available, we will take a deep dive into the world of aluminum extrusion.


At the end of this article, you’ll have a better understanding of aluminum extrusion in general, including the processes involved in making it, its uses, its Pros/Cons, and the shapes, sizes, and profiles you can get.


Let’s dive right in.



History of Aluminum Extrusion


The first patent for the extrusion process was taken out in 1797 by Joseph Bramah, and the process included using a hand-driven plunger to drive a preheated soft metal through a die. Thomas Burr introduced a hydraulic press instead of a hand-driven plunger in 1820, a process referred to as ‘squirting.’


Brass and copper alloys were added to the process in 1894, and aluminum came onto the scene in 1904. The increased demand was driven by World War II, where it was used in the manufacture of war equipment, and it continued being popular in the building and construction industry after the war.


Aluminum Extrusion Sizes and Profiles


The beauty of the extrusion process and the reason why aluminum is such an excellent extrusion material is that it can be produced in an almost limitless variety of shapes, sizes, and profiles. There are four main classes of extrusion shapes, as follows:


    Solid Shapes: Creating solid rods and bars with cross-sectional profiles such as squares, rectangles, and circles is possible.

     Semi-solid Shapes: You can make shapes such as channels, angles, circles, etc

     Hollow Shapes: Instead of being solid rods, these are hollowed out in profiles such as squares

   Custom Aluminum Extrusion Shapes: Certain customers will require specific profiles for their purposes, which will require specialized production processes. According to the client's needs, producers can deliver extrusions with interlocking shapes, varying color profiles, and so on.


How to Choose the Right Extrusion Size and Profile


The size and profile you choose for your project will determine the strength and structural integrity of whatever you make with it, which is why it should be chosen very carefully. Two profiles of 45x45 mm dimensions might provide very different levels of rigidity depending on the profile and internal moment of inertia.


Engineers have figured out that the best way to estimate the performance capabilities of aluminum profiles is by calculating the ratio of the area moment of inertia against its surface area. The cross-sectional area of the extrusion will also influence its overall weight.


Even though aluminum is a strong, durable metal, it might still fail if placed under unreasonable stress.


Safety Factorization


Every use case for aluminum extrudates should have a suitable safety factor (SF) calculation carried out in advance. If a structure is designed to theoretically fail when subjected to 1000N of force, assigning a safety factor of two will mean its maximum load limit will be 500N. Your safety factor is essentially a representation of how confident you are about the accuracy of your calculations.


There are certain factors and variables you need to consider when determining your factor rating, which include:


       The cost of overbuilding

       The potential consequences of failure

       The environmental conditions that your structure will have to face

       The thoroughness and calculation accuracy of your projections


It’s important to note that you should always align your safety factors to the industry standards in your location. Should there be any risk of personal injuries occurring due to system failures, the prudent action will be to increase the safety factor.


Bending Stress Limits


Basic static calculations and fire body diagrams are what engineers use to estimate the applied load your structure will be expected to bear and evaluate whether or not a profile size will meet your design requirements. Each extrusion should be subjected to these calculations as a structure will only bear as much load as its weakest component.


Once you have this value, your next step will be to use the appropriate formulas to arrive at your extrusions' maximum bending stress limit and maximum deflection limits.


To get your extrusion’s ability to withstand the load you require, take the material’s yield strength and compare it with the maximum bending stress limit. Note that the value you arrive at will only be an estimate because it does not consider the shear stress factor and the extrusion’s weight.


Buckling Strength Limits


Buckling is a major consideration for engineers when calculating a structure’s strength. When a log vertical beam is put under a compressive force, there is a risk of buckling if it’s unable to withstand it. Buckling typically bends the beam outwards, gradually reducing its structural integrity and potentially leading to sudden structural failure.


Vertical beams are the most susceptible to this type of failure because their load will be greater than the force acting on the rest of the structure due to the effects of gravity.


Euler’s critical load formula is what we use to calculate the maximum allowable buckling load for a structure. Once you determine the end conditions that will match your scenario based on the types of joints that you’re going to use, you can calculate the maximum load capacity using the area moment of inertia and the extrusion’s area length factor.


Extrusion Shapes


There are simple extrusion shapes you can choose from when ordering extrusions, which will depend on your purposes. These are the basic and most common shapes available, which you can order in sizes generally ranging from 6mm all the way to 120mm.


 Angles: Aluminum extrusion angles come in equal and unequal dimensions according to the client’s requirements. You can find them in equal angles or unequal angles. Angles as small as 5 degrees and as wide as 179 degrees are simply achieved.

    Bars: Solid aluminum bars can also be produced in various shapes, which their eventual purpose will largely determine. It’s possible to order solid flat bars, square bars, round bars, rectangular bars, and so on.

    Tubes: Tube shapes are the simplest hollow profile shape you can order as an extrusion, and has many unique advantages and benefits. They are often used in industrial applications such as the making of structural components such as machinery, vehicles, frames, and so on. You can order round, square, and rectangular tubes of various sizes.

    U-Channels: These are a special extrusion shape that looks like a square or rectangle with one of its four sides taken off. It’s used in various applications, such as architectural trim, formwork brackets, and structural support.


The Aluminum Extrusion Process

Let's take a quick look at the extrusion process to better understand what aluminum extrusion is and get a better idea of the final results.


     Step 1: The die will be prepared and loaded into the extrusion machine and heated to 450-500 degrees Celsius to keep the extrusion metal flowing evenly through it.

   Step 2: The metal billet will then be cut from a log of aluminum and then preheated to 450-500 degrees in order to make it malleable enough for the extrusion process.

     Step 3: The heated billet will then be mechanically moved to the press after some form of lubrication is placed on it. A releasing agent will also be applied to it so that it doesn’t stick to the ram.

    Step 4: A hydraulic ram will then apply up to 15,000 tons of pressure on the billet, pushing it into the press container.

    Step 5: The pressure will cause the billet to push against the die, forcing it to squeeze through the only opening available - the die opening - taking whichever profile this opening is cut.

     Step 6: Once it has passed through the die, it will be gripped by a puller which will draw it out onto a runout table, where it will be ‘quenched’ using running water.

   Step 7: The extruded aluminum will then be sheared to the required length while being maintained at an optimal temperature.

    Step 8: Once they are sheared, the extrusions will be transferred to a cooling table and left there until they come back down to room temperature. At this stage, any stretching that’s required will take place. Sometimes extruded profiles will have twists in them, which is an error that must be corrected by stretching.

    Step 10: After being straightened and work-hardened, they will be moved to a saw table and cut to various lengths. These will typically range between 8 and 21 feet. After this, they will be placed in an aging oven at specific temperatures.

     Step 10: The finishing process for aluminum extrusion might include heat treatment (improving yield and tensile strength), and surface finishes can improve their corrosion resistance and aesthetic appeal.


Types of Aluminum Extrusion


The main factor that makes aluminum such as a popular metal for extrusion is its durability, strength, and capacity for customization. These are the most commonly used extrusion methods:


Direct Extrusion


Also known as forward extrusion, this is the most commonly used extrusion method. It involves using a high-pressure hydraulic ram to push billets of aluminum through the die and is named as such because the extrusion will move in the same direction as the ram.


The reason direct extrusion is popular is the fact that it allows for higher-quality surface finishes and larger profile designs.


Indirect Extrusion


Here, the billet will be placed on a stationary container and secured in place. The die will then be pushed against the billet using a hollow ram, forcing the extrusion to push through the die opening. The method is referred to as indirect extrusion or backward extrusion because the extrudate moves in an opposite direction to the ram.


Indirect extrusion produces less friction, uses less energy, and produces less heat. The advantage of this method is that it gives us better control over the product’s material properties, consistency, and grain size. On the other side of the coin, it cannot produce large profile extrusions because they will be limited to the size of the hollow ram. You might often encounter surface impurities in the final product because of surface impurities from the billet.


Cold and Hot Extrusion


These types of extrusion are determined by the temperature of the billet relative to the room temperature. In hot extrusion, the billet will be heated far above the metal’s recrystallization temperature, making it much easier to push through the die.


Warm extrusion involves heating the billet higher than room temperature while keeping it below the recrystallization point. In cold extrusion, the metal will not be heated at all and so will be extruded while still at room temperature.


Warm and cold extrusion are favored options for producers who want to maximize the hardness and strength of the final product, and is suitable for metals such as aluminum thanks to its high ductility.


Cold and warm extrusion processes are usually used in indirect extrusion operations. While these methods have advantages, the die’s lifespan will be significantly shorter, and subsequent tooling will be harder.


Final Thoughts

All aluminum extrusions are standardized according to the GB5237.1-2017, which provides a guideline for the size, shape, and profile of extrusions. Standardization makes it possible for all manufacturers worldwide to produce similar products. In spite of these standardization protocols, the reality is that not all producers are alike.


Various factors will affect the quality, durability, strength, functionality, and affordability of the aluminum extrusion you order. Because of this, it’s important that you select your aluminum producer very carefully and only settle for companies with a proven record of high quality, experience, promptness, cost-effectiveness, and global reach.


Weiye Aluminium is your best bet when it comes to receiving the very best Best of luck on your next project!