What Is Aluminum Extrusion?
By Slot & Shaft. Updated November 4, 2026.
Aluminum extrusion is a manufacturing process that pushes a softened (but still solid) aluminum billet through a shaped steel die, producing a long part with the same cross-section along its entire length. The finished pieces, called extrusions or profiles, are used in everything from truck trailers and electronics housings to the T-slot framing behind DIY desks and workbenches.
Source: Aluminum Extruders Council (AEC).
How is aluminum extruded?
The Aluminum Extruders Council compares it to a Play-Doh press: push the material through a shaped opening and it comes out in that shape (AEC). In a real plant:
- Die and billet are prepared. A steel die is made for the profile, and an aluminum billet (a cast “log”) and the tools are preheated.
- The billet is heated, not melted. Aluminum melts at about 1,220 °F (660 °C). Extrusion typically runs with the billet above 700 °F (375 °C), and up to 930 °F (500 °C) depending on alloy.
- A hydraulic press pushes it through the die. Presses range from 100 to 15,000 tons; the press size limits how large a profile it can make.
- The profile is cooled and aged. It may be quenched, stretched and aged to reach its final strength.
- Finishing and fabrication. Profiles are cut, machined, anodized or painted, and packed.
Source for every temperature and press figure in these steps: AEC, Aluminum Extrusion Process.
What shapes can aluminum be extruded into?
Almost any constant cross-section that fits the press. Extruded profiles fall into three broad categories (BWC Profiles):
| Shape category | What it means | Examples |
|---|---|---|
| Solid | No enclosed voids | Flat bar, angle, channel |
| Semi-hollow | Partly encloses a void | Deep, narrow channels |
| Hollow | One or more fully enclosed voids | Tube, T-slot profiles with a center bore |
Hollow profiles need a die with a mandrel. The aluminum splits around the mandrel’s supports and welds back together under pressure (AEC).
What are T-slot aluminum extrusions?
T-slot extrusions are hollow profiles with a slot running the full length of one or more faces. A T-shaped nut slides into the slot, so you can bolt brackets, panels and other profiles anywhere along the bar and move them later. That makes them a reusable building system: no welding, and every joint can be undone.
Common T-slot sizes
Metric T-slot profiles are named by their outside size in millimeters. The slot width decides which nuts and bolts fit.
| Profile | Size | Slot width | Bolt | Weight per meter | Source |
|---|---|---|---|---|---|
| 2020 | 20 × 20 mm | 6 mm | M5 | 0.5 kg/m | MISUMI HFS5-2020 (catalog p. 2686) |
| 3030 | 30 × 30 mm | 8 mm | M6 | 0.9 kg/m | MISUMI HFS6-3030 |
| 4040 | 40 × 40 mm | 10 mm | M8 | 1.73 kg/m | MISUMI HFS8-4040 |
| 8040 | 80 × 40 mm | 10 mm | M8 | 3.0 kg/m | MISUMI HFS8-4080 (catalog p. 2768) |
Values are MISUMI’s published figures for the reference profiles in the Source column. Other brands with the same size name can differ, especially in slot width. More sizes in the aluminum extrusion sizes chart.
Which aluminum alloys are used for extrusion?
The 6xxx series (aluminum with magnesium and silicon) is the most popular extrusion alloy class: good strength, corrosion resistance, machinability and weldability, and it can be heat-treated (AEC, Alloys & Tempers). A designation like 6063-T5 means a 6xxx alloy that was cooled from an elevated temperature and artificially aged (AEC). The T-slot profiles we reference use A6005C-T5 (MISUMI).
What is aluminum extrusion used for?
- Transportation: truck trailers, aerospace and automotive crash management systems, where low weight and impact absorption matter
- Electronics and lighting: heat sinks, housings and reflectors, where aluminum’s heat conduction and reflectivity help
- Building and construction
- Machine frames and DIY: T-slot frames for automated equipment, workbenches, enclosures, desks and shelving
Transportation, electronics and construction uses: AEC, Extrusion Advantages. Machine-frame use: MISUMI.
Pros and cons of aluminum extrusion
Pros (all from AEC):
- Light: about 1/3 the weight of steel.
- Doesn’t rust: a natural oxide layer protects the surface; anodizing adds more protection.
- Recyclable: aluminum can be recycled indefinitely without losing its properties.
- Low tooling cost compared with other processes, so custom shapes are practical.
Cons:
- Hardware has to match the profile. Slot widths differ between profiles that share a size name.
Aluminum extrusion vs steel tube vs wood for DIY furniture
| T-slot aluminum extrusion | Welded steel tube | Wood | |
|---|---|---|---|
| Weight | About 1/3 of steel (AEC) | Heaviest | Depends on species |
| Rust / moisture | Doesn't rust (AEC) | Rusts unless coated | Can swell or warp with moisture |
| Tools to build | Hex key; cut-to-length parts | Welder, grinder | Saw, drill, clamps |
| Adjust or rebuild later | Yes: unbolt and reconfigure | No: welded | Partly: screw holes wear |
FAQ
What is aluminum extrusion in simple terms?
Squeezing softened aluminum through a shaped hole, like toothpaste from a tube, to make long pieces with a fixed cross-section (AEC).
Is aluminum melted during extrusion?
No. The billet is heated to roughly 700–930 °F (375–500 °C), well below aluminum’s melting point of about 1,220 °F (660 °C). It’s soft but still solid (AEC).
What are the main aluminum extrusion shapes?
Solid, semi-hollow and hollow. T-slot framing profiles are hollow shapes with slots along their faces (BWC Profiles).
What does 4040 mean in aluminum extrusion?
A profile 40 mm × 40 mm in cross-section. The name doesn’t tell you the slot width, so check that separately before buying nuts and bolts. See 4040 aluminum extrusion.
Is aluminum extrusion strong enough for furniture?
For desks, tables, shelves and workbenches, yes, if the profile size and joints suit the span and load. Each Slot & Shaft load-bearing design shows its own load note and disclaimer instead of a single generic number.
Is aluminum extrusion recyclable?
Yes. Aluminum can be recycled indefinitely with no loss of properties, and extrusions are often made with high recycled content (AEC).
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