Aluminium 6061 and 7075 — Engineering Grades for CNC Parts
Aluminium alloys are the workhorse material for CNC machined prototypes and production parts. At SkillsProto we machine 6061 and 7075 stock every day for UK product teams — covering most of the strength, corrosion and machinability combinations you need from an aluminium part.
If you need a part that is light, strong, easy to anodise and fast to machine, aluminium is almost always the answer.
6061 vs 7075 at a glance
| Property | Aluminium 6061-T6 | Aluminium 7075-T6 |
|---|---|---|
| Tensile strength | 310 MPa | 572 MPa |
| Yield strength | 276 MPa | 503 MPa |
| Density | 2.70 g/cm³ | 2.81 g/cm³ |
| Elongation at break | 12% | 11% |
| Corrosion resistance | Very good | Moderate (less than 6061) |
| Weldability | Excellent | Poor (crack sensitive) |
| Machinability | Excellent | Good (slightly more aggressive on tools) |
| Anodising response | Excellent (Type II colour anodise, Type III hard) | Good |
| Typical cost | Lower | Higher (~30%) |
| Common uses | Enclosures, brackets, jigs, general engineering | Aerospace, motorsport, high-stress structural |
When to choose 6061
- General-purpose structural parts, enclosures, brackets.
- Parts that need welding (bike frames, chassis).
- Parts that need anodising in custom colours with consistent results.
- Cost-sensitive projects.
When to choose 7075
- High-stress, weight-critical parts (motorsport, aerospace, robotics).
- Parts that need higher fatigue resistance than 6061.
- Drive components, gears, splined shafts, structural links.
CNC machining notes
- Tolerances to ±0.05 mm are achievable on critical features.
- Standard tolerance per ISO 2768-m.
- We hold stock in 6061-T6 plate, bar and billet; 7075-T6 plate and bar.
- Typical prototype lead time 3–7 working days.
Finishing options
- Anodising (Type II colour, Type III hard) — corrosion resistance + colour.
- Bead blasting — uniform matte finish.
- Powder coating — durable colour, RAL matched.
- Polishing / brushed — cosmetic finish for premium products.
- Chromate conversion (Alodine) — paint-ready surface and corrosion protection.
Frequently Asked Questions
Q1: Which aluminium should I pick for an anodised enclosure — 6061 or 7075? A: 6061. It anodises more uniformly and at lower cost. 7075 anodises fine but with less colour consistency.
Q2: Can you weld 7075? A: We strongly advise against welding 7075 — it is crack sensitive. Use 6061 for welded structures and 7075 for machined structural components.
Q3: What is the largest aluminium part you can handle? A: 600 × 400 × 300 mm stock; larger parts are quoted on request. We also bond and weld sub-assemblies for larger structures.