Aluminium Extrusion Tolerances Explained
When you are buying or designing bespoke aluminium profiles, understanding extrusion tolerances plays a vital role. They define how much variation is allowed between your drawing and the finished extrusion, and they determine whether parts fit perfectly or cause problems during assembly.
What Are Tolerances?
Tolerances are the permissible dimensional variations in an aluminium extrusion. Even with precision tooling, aluminium expands as it exits the die and contracts slightly as it cools.
For example, a 50 mm dimension with a ±0.15 mm tolerance means the finished part can measure between 49.85 mm and 50.15 mm. Anything outside that range is out of specification.
The Standards
Most reputable suppliers manufacture to the following recognised standards:
EN 755-9 for general extruded profiles, bars, and tubes, and
EN 12020-2 for precision and architectural profiles.
These standards define allowable variations for width, height, wall thickness, straightness, and twist, depending on the profile size and complexity.
What Affects Tolerances
Several factors influence achievable accuracy:
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Profile design. Simple shapes hold tighter limits than complex multi-chamber sections. – Aluminium Design – Extrusions | Love Aluminium
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Wall thickness. Thin walls expand more during extrusion.
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Alloy choice. 6063 and 6060 offer excellent precision, while 6082 provides more strength but slightly less flow.
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Press size and tooling. Smaller presses produce finer detail and greater consistency.
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Finishing. Anodising or powder coating can cause minor dimensional changes that should be considered at the design stage.
Our Approach at Love Aluminium
Every bespoke project is reviewed individually. We confirm achievable tolerances before die manufacture begins and maintain quality through precise straightening, cutting, and inspection.
Whether you need decorative trims or structural frames, we ensure your profiles meet the required dimensional accuracy every time.
Looking for guidance on tolerances for your next extrusion?
📧 Get in touch with Love Aluminium, your trusted UK partner for bespoke aluminium profiles.
