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Aluminum alloy selection
The alloy decides strength, corrosion resistance, thermal conductivity and how easily the part machines and finishes. Here's how to choose — starting with the most-asked comparison.
6061 vs 6063 aluminum
The most common question. Both are 6xxx (Mg+Si) alloys and anodize well, but they trade strength for finish:
6061
- Stronger (higher tensile/yield)
- Excellent for structural and machined parts
- Good weldability (5356/4043 filler)
- Slightly harder to get a perfect bright anodize
6063
- Better surface finish and anodize response
- Ideal for architectural & extruded profiles
- A little softer / less strong
- Easier to extrude into thin, complex sections
Rule of thumb: structural or heavily machined → 6061; decorative extrusion or best anodize → 6063. Many heatsinks use 6063 for finish, structural frames use 6061.
The other common alloys
| Alloy | Strength | Corrosion | Use |
|---|---|---|---|
| 6063 | Medium | Very good | Extrusion, finish, heatsinks |
| 6061 | High | Good | Structural, CNC, weldments |
| 6082 | High | Good | EU structural (EN AW-6082) |
| 7075 | Very high | Fair | Aircraft, high-stress |
| 1070 / 1060 | Low | Good | Skived fins (thermal conductivity) |
Aluminum vs copper heatsink (quick note)
Copper conducts heat better but is heavier, dearer and harder to finish; aluminum is the default for most electronics because it's light, cheap and anodizes well. Choose copper only where peak conductivity outweighs cost and weight. Aluminum liquid cold plates cover most high-power needs.
Need help choosing?
- Tell us strength vs finish priority — we'll pick 6061 or 6063.
- EU projects often specify 6082.
- For pure thermal fins, 1070/1060 maximizes conduction.