At Wiley we never stop thinking about and looking at metal fabrications. It’s what motivates us to get better at what we do. Even when we’re not at work we can’t help noticing fabricated structures all around us. Whether we’re loading a trailer, sitting on bleachers or contemplating a canopy for a boat, metal fabrications are always on our mind
Aluminum Extrusion is All Around
Many of those fabrications, like the three just listed, use extruded aluminum section. As you may have noticed, we’re fans of this material. That’s because it simplifies fabrication assembly while improving strength and stiffness. It’s also lightweight, corrosion-resistant and good-looking. (You can polish it to a shine, anodize it, coat it or paint it.)
These properties make it ideal for a wide range of applications. In fact you might be surprised to learn just how many uses for extrusion there are. We’ll list some of the most common ones below, but first, it might be helpful to explain what extrusions are and how they’re produced.
Extrusion Process Basics
When we say a material was extruded we mean it was pushed through a hole or opening to come out as a long length with a uniform cross-section. Some call it the toothpaste process, because squeezing the white, or stripey, paste from the tube is extrusion.
Extruding aluminum is a little more complex, although the idea is the same. A billet of aluminum is first heated to around 900°F before being loaded into a chamber in an extrusion press. A ram applies pressure to the billet, forcing it to flow through a small opening at the opposite end of the chamber. This opening, which is machined into a block of tool steel, creates the cross-section or profile that the aluminum takes on.
Extrusion is a continuous process that can produce hundreds or even thousands of feet of extrusion. (Confusingly, extruded material is often called “extrusion” just like the process.)
Extruded aluminum emerges from the die at over 900°F and moves onto a “leadout” table. Here it’s cut to length and quickly moved out the way of the material that just keeps on coming. It then cools on a “stretching” table before being cut down to lengths suitable for shipping.
One of the features of the extrusion process is that it can produce an almost limitless variety of profiles. These are classed as solid, hollow and semi-hollow.
Square, rectangular and round bar are the least complicated profiles and are examples of solid extrusions. Hollows are essentially tubes, square, round, rectangular or any other shape. As the name implies, the profile completely encloses an empty space.
For semi-hollow extrusion, picture a “C” shape. It’s closed most of the way round with just a small opening in the profile.
In general, extruded aluminum has great dimensional stability. Semi-hollow section shows the most variability, although still very little, due to a tendency to open out slightly.
Why Use Aluminum Extrusion?
Aluminum is a fascinating material with characteristics that make it especially useful whenever low weight, corrosion-resistance, strength, appearance or thermal or electrical conductivity are important. Extrusion gives it whatever cross-section is desired, which can incorporate a host of useful features. Tee-slots for holding nuts captive are one example, stiffening ribs another.
Another point in favor of extrusion is cost. Extrusion dies are far less costly than those for molding or casting, and can be produced in much less time. In addition, the process itself is relatively inexpensive to operate.
Common Applications of Extruded Aluminum
Producing a list of the top 10 applications would mean debating definitions and whether to use tons, yards or dollars. We argue enough as it is, so we’ve just gone with an alphabetical list drawn from what we know.
- Architecture and Construction
This category of applications ranges from railings and balustrades to building facades and bleachers. Stiff and lightweight aluminum section is ideal for applications like canopies where the structure can’t weigh much but must handle a load. (High stiffness means you need less of it, which translates to more weight-saving.) It’s also used for suspended ceilings and in walls.
It might be a stretch to include it under Construction, but many ladders are made from aluminum extrusion.
- Display equipment
Almost every stand you’ve ever seen at a trade show or exhibition was constructed with extruded material. That’s because extruded section can be designed so pieces interlock, making assembly quick and easy. It’s easy to move around too, and it can be finished any number of ways for an attractive and durable appearance.
In the same vein, point-of-sale displays, picture frames and display cabinets are other examples of aluminum extrusion used for display.
- Electrical Systems
As it’s a good conductor, extruded aluminum is sometimes used for busbars and related electrical equipment. Another application is in lighting. Modern LED fixtures in particular can have thermal management challenges. Aluminum extruded with fins makes an excellent radiator or heat exchanger, is easily mounted to and colored, and doesn’t weigh too much when mounted overhead.
A third electrical example is the use of aluminum extrusion in photovoltaic (solar) panel support structures. These need strength and corrosion-resistance, coupled with low mass, especially in the case of roof-mounted panels.
Walk through any factory, (ours included,) and you’re almost guaranteed to see aluminum extrusion being put to work. It’s the material of choice for equipment like workbenches, inspection tables and carts because it’s easy to cut and drill, lightweight yet stiff, and good value-for-money. It also has the added attraction of being extendible: if a workbench needs modifying that’s quickly done.
In the same factories you’ll often also see extrusion used to create frames for machine guarding. It goes together quickly and can be fitted with Lexan panels for a clear view while protecting people working nearby.
Weight and lightweighting are big concerns in transportation. Aerospace is an obvious example, but then there are automotive applications like trailers. Keeping trailer weight low lets the tow vehicle expend more torque on hauling stuff and less on moving the trailer itself. Note that this applies as much to horse and boat trailers as it does to 53’ semi trailers.
Aluminum extrusion is used extensively in RV’s for the same reason. Plus it won’t rust and can be polished up to look almost like chrome, so it’s good for decoration too.
Thinking about uses for aluminum extrusion
If you think about metal fabrications as much as we do you’ll spot them everywhere. Take a closer look and you’ll see many were built using aluminum extrusion. It really is the most extraordinarily versatile material, and that’s why we like working with it. If you’re wondering whether extruded aluminum might be a good choice in your next project, talk to us.