Aluminum CNC Machining
The most versatile lightweight metal in CNC machining.
Aluminum — The Ideal CNC Material
Aluminum is the most widely processed lightweight metal in CNC machining. With a density of just 2.7 g/cm³ — roughly one-third of steel — it offers an excellent strength-to-weight ratio. At the same time, aluminum can be machined at cutting speeds of up to 800 m/min, enabling short cycle times and cost-effective production.
In modern manufacturing, aluminum is used across virtually all industries: aerospace, automotive, medical technology, mechanical engineering, and electronics. Its good corrosion resistance through a natural oxide layer, excellent thermal conductivity, and the ability to be anodized make aluminum a true all-rounder.
Key Aluminum Alloys for CNC Machining
| Alloy | Material No. | Properties | Typical Application |
|---|---|---|---|
| AlMg3 | EN AW-5754 | Good corrosion resistance, weldable | Housings, covers, shipbuilding |
| AlMg4.5Mn | EN AW-5083 | Seawater resistant, high strength | Marine, pressure vessels |
| AlMgSi1 | EN AW-6082 | Universal alloy, anodizable | Mechanical engineering, construction |
| AlCuMg2 | EN AW-2024 | Highest strength, not weldable | Aerospace, highly stressed parts |
| AlZnMgCu1.5 | EN AW-7075 | Highest strength (570 MPa), aerospace standard | Aerospace, motorsport, military |
At Strobel Industry, we machine all common aluminum alloys. The most frequently requested are EN AW-6082 (mechanical engineering) and EN AW-7075 (high-strength). → CNC Milling
Optimal Cutting Data for Aluminum
Due to its low strength and high thermal conductivity, aluminum allows significantly more aggressive cutting data than steel:
| Parameter | Milling | Turning |
|---|---|---|
| Cutting speed vc | 300–800 m/min | 200–600 m/min |
| Feed fz | 0.05–0.20 mm/tooth | 0.10–0.30 mm/rev |
| Depth of cut ap | up to 1×D (full slot) | up to 3 mm |
| Tool | Polished solid carbide, 2-3 flutes | Diamond coated |
| Coolant | Emulsion or MQL | Emulsion |
Pro tip: For best surfaces on aluminum: use polished solid carbide end mills with 2 flutes, run high RPM, and use climb milling. Built-up edge formation is prevented by high vc and sharp tools.
Surface Treatment and Finishing
Aluminum offers a wide range of surface finishing options:
- Anodizing — Hard oxide layer (5–25 µm), color options, corrosion protection. Standard for visible parts.
- Hard Anodizing — Thicker layer (25–100 µm), extremely wear-resistant (HV 400–500). For functional surfaces.
- Chromating — Thin corrosion protection, electrically conductive. For electronics housings.
- Powder Coating — RAL colors, robust, UV-resistant. For outdoor applications.
- Electroless Nickel Plating — Uniform coating even inside bores. For wear protection.
We deliver aluminum parts with all common surface treatments through our partner network.
Design Tips for Aluminum CNC Parts
To ensure your aluminum parts can be manufactured optimally, follow these design guidelines:
- Wall thickness: Minimum 0.8 mm for milled parts, 0.5 mm for turned parts. Thinner walls vibrate and deform under cutting pressure.
- Internal radii: Provide at least half the end mill diameter as internal radius. 90° corners require expensive EDM.
- Threads: Minimum 1.5×D engagement depth (aluminum is softer than steel). Thread inserts (Helicoil) for frequently assembled joints.
- Fits: H7/h6 fits are easily achievable. For press fits: consider the thermal expansion coefficient (23.1 × 10⁻⁶/K).
- Deep pockets: Depth-to-width ratio max 4:1 for stable machining. Deeper pockets increase machining time exponentially.
Tip: Send us your drawing — we check manufacturability for free and provide optimization suggestions. → Contact
Tolerances and Dimensional Accuracy
Aluminum can be machined to very tight tolerances:
| Tolerance Class | Range | Typical Application |
|---|---|---|
| Standard | ±0.1 mm | General mechanical engineering, housings |
| Fine | ±0.05 mm | Fits, guides |
| Precision | ±0.02 mm | Optics, metrology |
| IT6 (h6/H7) | 0.013–0.022 mm | Shafts, bearing seats |
Important: Aluminum has a high thermal expansion coefficient (23.1 × 10⁻⁶/K). For parts with tight tolerances, measuring temperature should be 20±1°C. A 200 mm aluminum part changes length by 0.046 mm with a 10°C temperature difference.
Industries and Application Examples
- Aerospace — Structural components, fuselage parts, seat brackets from EN AW-7075 and EN AW-2024. Highest strength requirements at minimal weight.
- Automotive — Motor mounts, transmission housings, cooling system components. Increasingly e-mobility: battery housings and inverters from aluminum.
- Mechanical Engineering — Guide rails, base plates, adapter plates from EN AW-6082. Universally applicable.
- Medical Technology — Housings for medical devices, operating table components. Anodized for hygiene and aesthetics.
- Electronics — Heat sinks, 19" rack enclosures, housings. Aluminum conducts heat 4× better than steel.
- Optics & Metrology — Carrier plates, adjustment elements. EN AW-6082 T651 stress-relieved for highest dimensional stability.
Frequently asked Questions
Which aluminum is best for CNC milling?
EN AW-6082 (AlMgSi1) is the most versatile milling material: good machinability, anodizable, moderate strength. For highest strength, we recommend EN AW-7075.
How much does CNC machining of aluminum cost?
Aluminum can be machined 2-3× faster than steel. Typical unit prices for milled parts: €30–200 (one-off) or €15–80 (small batch). Request a specific quote.
Can aluminum be anodized?
Yes — all 5xxx and 6xxx alloys are excellent for anodizing. 7xxx alloys have limited anodizing capability. 2xxx alloys (copper-containing) are not ideal.
What is the difference between AlMg3 and 7075?
AlMg3 (EN AW-5754) is corrosion-resistant and weldable but softer (190 MPa). 7075 is high-strength (570 MPa) but not weldable and less corrosion-resistant. The choice depends on the application.
What tolerances are achievable with aluminum CNC parts?
Standard: ±0.1 mm. Fine: ±0.05 mm. Precision: ±0.02 mm. IT6 fits (h6/H7) are easily achievable on our DMG MORI machines. Important: Consider thermal expansion for tight tolerances.
How quickly can aluminum parts be delivered?
Express: 3–5 business days for simple parts. Standard: 10–15 business days. EN AW-6082 and EN AW-7075 are available from stock. Special alloys may have 2–4 weeks lead time.
Is aluminum weldable?
Yes — especially 5xxx alloys (AlMg3, 5083) are excellent for TIG/MIG welding. 6xxx alloys are conditionally weldable (strength loss in the heat-affected zone). 2xxx and 7xxx are not or poorly weldable.
What minimum wall thickness is required for aluminum milled parts?
Recommended minimum wall thickness: 0.8 mm for milled parts. Thinner walls are possible but require adapted machining strategy (reduced depth of cut, support structures) and increase costs. Below 0.5 mm becomes critical.
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