How many round aluminum tubes do you know?

Ever faced a project needing aluminum tubes¹ and felt lost in the options? It's easy to get confused. Picking the wrong type can cause real headaches down the line, affecting performance or even safety.

Round aluminum tubes are diverse, primarily categorized by alloy (like 6061 for strength, 6063 for finish), manufacturing method (extruded or drawn), and temper (like T6 for hardness), each tailored for specific structural, fluid conveyance, or mechanical uses.

At SWA Forging, while our main focus since 2012 has been on large-diameter forged rings and discs, we deal with aluminum alloys day in and day out. Our clients, often traders or machining companies in the Middle East, sometimes work with tubular components or assemblies that incorporate our forgings. So, understanding the full spectrum of aluminum products, including tubes, is part of our world. Let's explore the common types you might encounter.

What is aluminium tube?

The term "aluminum tube" seems straightforward, right? But if you're specifying it for a project, a vague idea isn't enough. You need to know exactly what you're dealing with to ensure it performs.

An aluminum tube is a hollow, cylindrical product made from various aluminum alloys, prized for its light weight, good strength-to-weight ratio, and excellent corrosion resistance, making it suitable for structural supports, fluid transport, and mechanical components.

An aluminum tube is essentially a long, hollow piece of aluminum with a circular cross-section. Think of it like a pipe, but typically the term "tube" implies more specific dimensional tolerances and often a wider range of alloys and tempers compared to general plumbing pipes. These tubes are valued for several inherent characteristics of aluminum itself: they are lightweight (about one-third the weight of steel), which is great for reducing overall mass in structures or moving parts. They also naturally form a protective oxide layer, giving them good corrosion resistance in many environments. Plus, aluminum is a good conductor of heat and electricity, and it's highly recyclable.
Most aluminum tubes you'll come across are made by extrusion. In this process, a heated aluminum billet is forced through a die with a circular opening (and a central mandrel to create the hollow). Some high-precision tubes are drawn, which involves pulling an extruded tube through a smaller die, often over a mandrel (Drawn Over Mandrel - DOM), to achieve tighter tolerances and a smoother surface finish. The specific alloy used, like 6061 or 6063, and its temper (e.g., T6) will dictate its final strength, hardness, and suitability for different jobs. For instance, some of our machining clients might use sections of thick-walled aluminum tube or hollow bar (which is very similar) to machine custom parts, valuing the material savings compared to solid bar.

What are the different types of aluminum tubing?

You know you need aluminum tubing, but then you see all the different codes and names. It can feel like a real maze. How do you pick the one that won't let you down?

Aluminum tubing types are differentiated by alloy (e.g., 6061 for structural, 6063 for architectural, 5052 for marine), manufacturing process (extruded for general use, drawn for precision), and temper (e.g., T6 for strength, O for high formability).

There are quite a few ways to categorize aluminum tubes, which helps in selecting the right one.
First, there's the alloy series. Different alloys have different strengths and weaknesses.

• 3xxx Series (e.g., 3003): Good formability and corrosion resistance, moderate strength. Often used for general purpose applications, like fluid lines or heat exchangers where pressure isn't extreme.
• 5xxx Series (e.g., 5052, 5083): Excellent corrosion resistance, especially in marine environments, and good weldability. You'll find these in boat railings or hydraulic lines.
• 6xxx Series (e.g., 6061, 6063): These are probably the most common. They offer a great balance of strength, corrosion resistance, weldability, and machinability. 6063 is often called an "architectural alloy" because it extrudes well with a good surface finish, perfect for window frames or railings. 6061² is stronger and more versatile for structural uses like frames, machine parts, or even bicycle frames. At SWA Forging, 6061 is a staple for our forged rings and discs.
• 7xxx Series (e.g., 7075): These are the high-strength heroes, often used in aerospace or high-performance sporting goods where weight and strength are critical.
  Then, there's the manufacturing method. Most round aluminum tubes are extruded. For applications needing tighter dimensional tolerances, better surface finish, and sometimes enhanced mechanical properties, drawn tubes (often called Drawn Over Mandrel or DOM tubes) are used.
  And finally, the temper is crucial. This tells you about the heat treatment or work hardening the tube has undergone. For example, "O" temper means annealed (soft), "T6" means solution heat-treated and artificially aged (strong and hard).

Here's a simple table:

Understanding these distinctions helps our clients, whether traders or machining companies, pick the ideal tube for their specific end-use.

How do you cut round aluminum tubing?

So you've got your aluminum tube, but now you need to cut it to length. You want a clean, straight cut, not a jagged mess. What's the best way to get professional results?

To cut round aluminum tubing cleanly, use a pipe/tube cutter for precise, burr-free cuts, a hacksaw with a fine-tooth blade for simple jobs, or a chop saw/miter saw fitted with a non-ferrous metal cutting blade for speed and accuracy.

Cutting aluminum tubing correctly is important for a good fit and a professional look. There are several tools you can use.
For very clean, perpendicular cuts with minimal burr, a pipe/tube cutter is excellent. This tool has a sharp cutting wheel and rollers that guide it around the tube. You tighten it slightly with each rotation, and the wheel scores deeper until it cuts through. It's great for thinner-walled tubes.
A simple hacksaw can also do the job. You'll want a blade with fine teeth, something like 24 to 32 teeth per inch (TPI), to avoid snagging. The trick is to apply steady, even pressure and keep your strokes straight. It's a good idea to mark your line all the way around the tube. After cutting with a hacksaw, you'll definitely need to deburr the edge with a file or a deburring tool.
For faster, more repetitive cuts, especially on thicker tubes, a chop saw or miter saw is very effective, but you must use the right blade. This means a carbide-tipped blade specifically designed for cutting non-ferrous metals like aluminum. These blades typically have a high tooth count and often a negative hook angle to prevent grabbing. Always clamp the tubing securely to prevent it from spinning or kicking back – this is really important for safety. Using a cutting fluid or lubricant can help give a smoother cut and prolong blade life.
Regardless of the method, always wear safety glasses! And after cutting, always check for and remove any burrs from both the inside and outside edges. Our machining clients are very particular about this, as burrs can affect assembly and performance.

What is the strongest aluminium tube?

When your project demands maximum strength from an aluminum tube, you can't just pick any type. Failure isn't an option. So, which aluminum tubes pack the most punch in terms of strength?

The strongest aluminum tubes are generally made from 7000 series alloys, like 7075 in the T6 temper. However, the tube's wall thickness and diameter also play a critical role in its overall structural strength and resistance to bending or buckling.

When it comes to sheer material strength, alloys from the 7xxx series are top-tier for aluminum tubes. Specifically, 7075 aluminum alloy, especially when heat-treated to a T6 temper (7075-T6), boasts one of the highest strength-to-weight ratios among aluminum alloys. Its tensile strength can be comparable to some mild steels, but at only about a third of the weight. This makes it a favorite for demanding applications like aerospace components, high-performance bicycle frames, and other sporting equipment where every gram counts and structural integrity is paramount.
Another strong contender is the 2xxx series, such as 2024 alloy in a T3 or T4 temper. These are also very strong and have good fatigue resistance, making them suitable for aircraft structures.
However, it's crucial to remember that the alloy is only part of the story. The physical dimensions of the tube – its outside diameter and, very importantly, its wall thickness – are equally critical in determining how "strong" the tube is in a practical sense. A thicker-walled tube made from a moderately strong alloy like 6061-T6 might actually resist bending or buckling better under certain loads than a very thin-walled tube made from ultra-strong 7075-T6. So, "strongest" needs to be defined by the application's specific load conditions (tension, compression, bending, torsion).
At SWA Forging, while we forge solid parts, we often work with high-strength alloys like 7075 for clients who need maximum performance. The principles of material strength and the importance of correct tempering apply just as much to tubes as they do to our forged rings and discs. Weldability is also a consideration; 7xxx series alloys are generally not recommended for welding as it significantly compromises their strength.

Conclusion

Round aluminum tubes offer a wide array of choices in alloy, size, and strength, making them incredibly versatile for many engineering and structural needs, from simple frames to high-tech components.