By: A Materials Engineer Who’s Spent a Lot of Time Around Molten Metal and CAD Drawings

The Story Starts with a Shape
Imagine you’re holding a curtain rod, a bike frame, or even the edge of your laptop. What do all these things have in common? Chances are, they started life as an aluminum extrusion profile.

Aluminum extrusion is like squeezing toothpaste out of a tube—except instead of toothpaste, it’s heated aluminum billet. And instead of a round hole, it’s pushed through a custom-shaped die to create long pieces with a constant cross-section. The result? A durable, lightweight, and versatile piece of aluminum that can be used just about anywhere.

But here’s the twist: not all extrusions are created equal. The profile shape, size, alloy, finish, and even the tolerances need to be specified with precision. If you’re an engineer, architect, designer—or just someone who likes to know how stuff works—this post will walk you through the basics of aluminum extrusion profiles and how they’re specified.

What Is an Aluminum Extrusion Profile, Really?
An aluminum extrusion profile is a continuous cross-sectional shape created by forcing aluminum through a shaped die. These profiles can be as simple as a flat bar or as complex as a hollow, multi-chambered architectural frame.

They’re widely used in industries like:

Construction (window frames, curtain walls, structural components)

Transportation (automotive, aerospace, marine)

Consumer products (furniture, appliances, electronics)

Industrial automation (machine frames, workstations)

Why aluminum? It’s lightweight, strong, corrosion-resistant, recyclable, and—bonus points—great for machining and finishing.

The Specification Blueprint: What to Define When Ordering or Designing an Aluminum Profile
Specifying an aluminum extrusion profile isn’t just about the shape. It’s about all the little details that make that shape functional and manufacturable. Here’s what needs to be considered:

1. The Profile Shape (Cross-Sectional Design)
The starting point of every extrusion is the profile shape.

You can choose from standard catalog profiles (think L-shapes, T-shapes, U-channels, tubes) or design your own custom profile.

Custom profiles are ideal for product integration, weight reduction, and cost savings—especially if you’re doing high-volume production.

Pro Tip: Keep wall thickness uniform where possible. It reduces die wear and ensures better extrusion consistency.

2. Alloy Selection
Not all aluminum is created equal. The most common alloys for extrusion are from the 6000 series, especially:

6061: Strong, machinable, weldable—used in structural components.

6063: Excellent surface finish, good corrosion resistance—great for architectural use.

Other alloys like 6082, 6106, or 6463 can be chosen based on strength, finish, or formability requirements.

3. Temper (Mechanical Properties)
The temper tells you how the alloy has been heat-treated. For example:

T5: Cooled from an elevated-temperature shaping process and artificially aged.

T6: Solution heat-treated and artificially aged (gives higher strength than T5).

Always match temper to the functional and strength needs of your application.

4. Dimensions and Tolerances
Specify exact width, height, wall thickness, and any critical dimensions.

Tolerances depend on profile complexity and extrusion standards. Most follow ISO 2768 or EN 755-9 standards for dimensional accuracy.

If a hole has to fit a bolt just right or if the profile slots need to line up across multiple pieces—this part really matters.

5. Surface Finish
Depending on the final use, you might want:

Mill finish (as-extruded, matte gray)

Anodized (oxidized layer for corrosion resistance, in natural or colored finishes)

Powder coating (for enhanced appearance and protection)

Mechanical finishes (brushed, polished)

Each finish affects the look, corrosion resistance, and sometimes dimensional tolerances.

6. Length and Cut Specifications
Most extrusions come in standard lengths like 6 meters (about 20 feet).

You can specify custom cut lengths, precision cuts, or fabrication like drilling, notching, or tapping.

If your profile needs to slide into another part or fit into a frame, these final details matter big time.

Common Mistakes to Avoid When Specifying
Let’s be honest—this stuff can get technical. But a few pitfalls come up again and again:

Overcomplicating the shape: Sharp corners, extreme thin walls, or inconsistent wall thickness can make extrusion hard or expensive.

Ignoring tolerances: Small mistakes here can lead to poor fit or assembly issues.

Choosing the wrong alloy/temper: This affects not just strength but how it reacts to machining or surface finishing.

Not planning for thermal expansion: Aluminum expands more than steel—important for long profiles or outdoor use.

A Real-World Example
Let’s say you’re designing a modular shelving system. You want sleek, sturdy horizontal beams that slot into upright supports, and you plan to run wires through internal channels.

Here’s how you’d specify it:

Custom profile shape with hollow chambers and grooves.

6063-T5 alloy for a clean finish and moderate strength.

Anodized natural finish for aesthetics and corrosion protection.

Tight tolerances on groove spacing for accessories.

Length: 1.2 meters, with precise end cuts and pre-drilled mounting holes.

Boom—you’ve just created an efficient, high-quality, and scalable component. And the extruder will love you for making their life easier with a clear spec sheet.

Final Thoughts: Getting the Most from Aluminum Extrusion
Aluminum extrusion profiles are everywhere for a reason—they’re incredibly versatile. But like any engineered solution, they need the right design and specifications to perform well.

Whether you’re creating something simple or architecturally ambitious, the process of specifying an extrusion profile is a mix of science, design, and a bit of negotiation with physics.

So next time you admire a slick piece of hardware, a minimalist light fixture, or the rail of a high-speed train—take a second to appreciate the precision and thought that went into that humble piece of extruded aluminum.

Need Help Specifying Your Next Profile?
As someone who’s worked with extrusion designers, die engineers, and even spent time on the production floor watching the billet squeeze out like hot spaghetti—trust me, the more accurate your specs, the smoother the process.

If you’ve got a profile in mind (or even just a sketch on a napkin), talk to a specialist or extrusion supplier early. They’ll help you optimize your design for strength, cost, and manufacturability.