Aluminum is the most popular material in CNC machining — and for good reason. It's lightweight, corrosion-resistant, highly machinable, and available in dozens of alloy grades, each engineered for specific performance requirements. But this abundance of options creates a common challenge: which aluminum alloy should you choose for your CNC machined parts?
The wrong alloy choice can mean parts that don't meet strength requirements, poor anodizing results, wasted material costs, or unnecessary machining difficulty. This guide covers the most commonly CNC-machined aluminum alloys, their properties, ideal applications, and how to select the right one for your project.
Aluminum alloys are classified by a four-digit numbering system. The first digit indicates the primary alloying element, which determines the alloy family's fundamental characteristics:
| Series | Primary Alloy | Key Characteristics |
|---|---|---|
| 1xxx | Pure aluminum (99%+) | Excellent conductivity, very soft, limited machining use |
| 2xxx | Copper | High strength, aerospace grade, poor corrosion resistance |
| 3xxx | Manganese | Moderate strength, good formability, sheet metal |
| 5xxx | Magnesium | Marine grade, good weldability, moderate strength |
| 6xxx | Magnesium + Silicon | Versatile, good machinability, excellent anodizing |
| 7xxx | Zinc | Highest strength, aerospace applications |
The temper designation after the alloy number (e.g., "-T6") indicates the heat treatment condition. T6 means solution heat treated and artificially aged — the most common temper for CNC machined parts, offering the best combination of strength and machinability.
If there's one aluminum alloy every CNC machinist knows, it's 6061-T6. It's the default choice for a reason — it does everything well and nothing poorly.
Key Properties:
Best for: General-purpose structural components, brackets, housings, fixtures, jigs, frames, consumer electronics enclosures, drone parts, and any application where a balance of strength, machinability, and surface treatment compatibility is needed.
Limitations: Not suitable for high-stress aerospace structures or applications requiring strength above 350 MPa. In these cases, consider 7075.
7075 is one of the strongest aluminum alloys available, approaching the strength of many steels while remaining one-third the weight. It's the go-to choice when strength-to-weight ratio is the primary design driver.
Key Properties:
Best for: Aerospace structural components, high-performance automotive parts, sporting equipment, firearms components, military hardware, and any application where maximum strength with minimum weight is critical.
Limitations: More expensive than 6061 (typically 2–3×). Cannot be welded without significant strength loss. Less corrosion-resistant — protective surface treatments are recommended.
2024 has been used in aircraft structures since the 1930s. It offers excellent fatigue resistance — critical for parts subjected to cyclic loading.
Key Properties:
Best for: Aircraft fuselage skins, wing structures, truck wheels, scientific instruments, and parts subject to cyclic or fatigue loading.
5052 offers the best corrosion resistance among common aluminum alloys, making it the default choice for marine environments and chemical exposure.
Key Properties:
Best for: Marine hardware, chemical processing equipment, fuel tanks, hydraulic tubes. Less commonly CNC machined due to lower machinability — better suited for sheet metal fabrication.
6082 is essentially Europe's answer to 6061, with slightly higher strength and very similar machining characteristics. Common in European specifications and increasingly used in Asian manufacturing.
Key Properties:
Best for: Structural components, bridges, cranes, transport applications. Direct substitute for 6061 in European-spec projects.
2011 is specifically formulated for maximum machinability. It contains lead and bismuth additions that produce small, easily broken chips and allow higher cutting speeds than any other aluminum alloy.
Key Properties:
Best for: High-volume screw machine parts, complex turned components, fittings, and connector bodies where surface treatment isn't required. Excellent on Swiss-type lathes for high-volume production.
Note: 2011 contains lead and is not suitable for food contact or medical applications. RoHS-compliant alternatives like 6262 are available.
| Property | 6061-T6 | 7075-T6 | 2024-T3 | 5052-H32 | 2011-T3 |
|---|---|---|---|---|---|
| Tensile (MPa) | 310 | 572 | 469 | 228 | 379 |
| Machinability | ★★★★ | ★★★½ | ★★★½ | ★★★ | ★★★★★ |
| Corrosion Resistance | ★★★★ | ★★★ | ★★ | ★★★★★ | ★★ |
| Weldability | ★★★★★ | ★ | ★★ | ★★★★★ | ★★ |
| Anodizing | ★★★★★ | ★★★★ | ★★★ | ★★★★ | ★★ |
| Cost (relative) | $ | $$$ | $$ | $ | $$ |
Aluminum's excellent machinability means fast cycle times and long tool life, but there are still important considerations for optimal results:
One of aluminum's greatest advantages is the variety of surface treatments available:
When designing parts for anodizing, keep in mind that the anodize layer builds both inward and outward from the original surface. Critical tolerance features should either be masked during anodizing or dimensioned to account for the coating thickness.
Use this simple decision tree to select the right aluminum alloy:
When in doubt, start with 6061-T6. It's the most widely stocked, most commonly machined, and most forgiving aluminum alloy. Only move to specialty grades when your application specifically demands properties that 6061 can't deliver.
For detailed tolerance information on what you can achieve with aluminum machining, see our CNC Machining Tolerance Guide, and for cost considerations, check our CNC machining cost breakdown.
KING HAN machines aluminum alloys daily across our Swiss-type and multi-axis CNC equipment. Send us your drawings and material requirements for a competitive quote.
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