Aluminum is one of the most widely used materials in CNC machining due to its excellent machinability, strength-to-weight ratio, and versatility.
Choosing the right aluminum grade is essential for achieving the desired performance, surface finish, and cost-efficiency in both prototyping and production environments.

This guide explains the key differences between common aluminum alloys, their mechanical properties, and best-use cases in CNC machining.

Why Aluminum Is Ideal for CNC Machining

Aluminum’s popularity in CNC machining is rooted in its unique combination of material and process benefits:

• 🌀 Excellent machinability – Cuts easily with low tool wear

• 🧲 Lightweight – Density ~2.7 g/cm³ (about one-third of steel)

• ⚙️ Corrosion resistance – Naturally forms a protective oxide layer

• 💨 High thermal and electrical conductivity

• 🌐 Recyclability – Environmentally sustainable material

• 🔩 Anodizing and surface treatment compatibility

It’s used across industries such as aerospace, automotive, robotics, consumer electronics, and industrial machinery.

To optimize performance, choosing the correct aluminum grade based on the application is critical.

Overview: Most Common Aluminum Grades for CNC Machining

Each of these grades behaves differently during machining, affecting tool choice, feed rate, chip formation, and part quality.

1. 6061 Aluminum: The All-Around Performer

6061 is the most commonly used aluminum alloy for CNC machining. It offers an ideal mix of strength, corrosion resistance, and machinability.

Key Properties:

• Medium strength

• Good weldability

• Excellent corrosion resistance

• Great for anodizing

• Affordable and widely available

CNC Behavior:

• Machines easily with high-speed steel or carbide tools

• Produces smooth finishes with minimal burr formation

• Good for tapping, drilling, and turning

Best for:

• Housings, brackets, enclosures

• Aerospace fittings

• Automotive engine parts

• Advanced CNC machining projects requiring tight tolerances and light weight

2. 7075 Aluminum: Built for Strength

7075 aluminum is known for its very high strength-to-weight ratio. It’s often used in aerospace and high-performance applications where stress resistance is critical.

Key Properties:

• Very high strength (comparable to some steels)

• Moderate corrosion resistance

• Poor weldability

• Slightly more expensive than 6061

CNC Behavior:

• Requires sharper tools and more controlled feed rates

• Less forgiving in threading and tight-tolerance drilling

• Responds well to high-speed finishing with cooling

Best for:

• Aircraft wing spars and fuselage frames

• Racing components and bike parts

• High-load structural supports

• Weapon components and high-performance assemblies

3. 2024 Aluminum: Aerospace Standard

2024 is another high-strength aluminum alloy widely used in aerospace and defense industries. It contains high amounts of copper, making it less corrosion-resistant but stronger in tension.

Key Properties:

• High fatigue strength

• Low corrosion resistance

• Poor weldability, but excellent fatigue resistance

• Often used with cladding or surface treatments

CNC Behavior:

• Requires protective coatings after machining

• Can experience work-hardening, making multi-pass cuts preferable

• Produces tight chips, demanding good chip evacuation

Best for:

• Aircraft fuselage and wing skins

• Military components

• Riveted structures and tension-based assemblies

4. 5052 Aluminum: The Marine Favorite

5052 is a non-heat-treatable aluminum alloy with exceptional corrosion resistance, especially in marine environments.

Key Properties:

• Medium strength

• Excellent corrosion resistance (saltwater and chemicals)

• Great weldability and formability

• Slightly softer than 6061

CNC Behavior:

• Easy to cut and bend

• May require slower spindle speeds to avoid work hardening

• Produces very smooth edges and fine finishes

Best for:

• Marine fittings and parts

• Electronic and power enclosures

• Architectural panels

• Welded assemblies and storage tanks

5. 6082 Aluminum: European Alternative

6082 is similar to 6061 in terms of properties but more widely used in Europe. It offers slightly higher strength and excellent anodizing characteristics.

Key Properties:

• High strength

• Good corrosion resistance

• Excellent anodizing results

• Often used in structural applications

CNC Behavior:

• Suitable for complex 3D milling operations

• Machines similarly to 6061 with good chip control

• Used in both CNC prototyping and production

Best for:

• Bridge parts

• Structural applications

• Hydraulic tubes

• CNC profiles for frames and mechanical systems

Choosing the Right Aluminum Grade: Key Factors

When selecting an aluminum grade for CNC machining, consider:

1. Mechanical Requirements

• Is strength, fatigue resistance, or lightweight most important?

2. Corrosion Environment

• Will the part be exposed to saltwater, chemicals, or moisture?

3. Post-Processing Needs

• Does the part require welding, anodizing, or painting?

4. Precision and Surface Finish

• How tight are the tolerances and cosmetic standards?

5. Budget Constraints

• Balancing cost vs. performance for prototyping or production

Each project has its own unique set of priorities—so matching the aluminum grade to the intended use is critical.

Surface Treatments and Finishing Options

Most aluminum grades respond well to:

• Anodizing: Adds corrosion resistance and cosmetic appeal

• Powder coating: Durable color finish for industrial use

• Polishing or bead blasting: For optical parts or matte textures

• Chemical film (Alodine): For conductivity with corrosion protection

Some alloys (like 2024 or 7075) benefit from anodizing more than others due to their copper content.

Summary Table: Aluminum Grades at a Glance

Final Thoughts

Aluminum is the metal of choice in modern CNC machining, offering unmatched flexibility across strength, corrosion resistance, and cost.
But not all grades are created equal. Choosing the right aluminum alloy depends on your specific application, machining conditions, and performance goals.

Whether you’re prototyping a consumer product or producing structural aerospace components, aligning your aluminum grade to your engineering specs is key to successful CNC manufacturing.

If you're seeking expert guidance or looking for tight-tolerance CNC aluminum parts, explore our advanced CNC machining services to ensure optimal results every time.