CNC machining aluminum

CNC machining aluminum alloy material selection

CNC machining is a traditional manufacturing process that uses drills and turning tools to create a part by removing material from a solid block of material. This process is fast, highly repeatable, and ideal for creating parts with tight tolerances. CNC machining can be done with any material that’s rigid enough to machine — from plastic to metal to fiberglass — and aluminum is a popular choice among product teams.

Broadly speaking, aluminum is a strong, non-magnetic, cost-effective material that is highly corrosion-resistant.

Here’s everything engineers and designers should know about the most common types of aluminum used for CNC machining, plus how to choose which type is best for their next project:

1. Aluminum 6061-T6

6061-T6 is one of the most popular aluminum alloys on the market and most manufacturing companies offer it as the standard grade for CNC machining. It’s versatile, easy to machine, and 6061 can even have different heat treatments.

6061-T6 is an excellent all-purpose material applicable to a wide variety of use-cases. Even though this material has a good strength-to-weight ratio, it’s ill-suited for high-stress applications. Common applications include automotive parts like chassis, bicycle frames, valves, computer parts, and much more.

Mechanical specifications:

  • Ultimate tensile strength: 310 MPa
  • Elongation at break: 17%
  • Modulus of elasticity: 68.9 GPa
  • Hardness: 60 HRB

2. Aluminum 7075-T6

For high-stress or high-performance applications, engineers should consider 7075-T6. This grade of aluminum is well known for its excellent strength-to-weight ratio and its hardness can even be comparable to that of some softer steels.

Widely used for high-stress applications in the aerospace and military industries, common applications include aircraft fittings, missile parts, and fuse parts. Certain high-performance bikes and sporting goods also include parts made from aluminum 7075-T6.

Despite its high strength and excellent mechanical properties, 7075-T6 does have its drawbacks. This material is less ductile and less resistant to corrosion than other grades. What’s more, aluminum 7075-T6 can be prohibitively expensive for some product teams.

Mechanical specifications:

  • Ultimate tensile strength: 434 – 580 MPa
  • Elongation at break: 10-15%
  • Modulus of elasticity: 69 – 76 GPa
  • Hardness: 79-86 HRB
  • Maximum service temperature: 100 °C

3. Aluminum 2024-T4

Aluminum 2024-T4 is a moderate- to high-strength alloy that offers good fatigue resistance and fracture toughness. Aluminum 2024-T4 isn’t as strong as 7075-T6, but it’s still suitable for aerospace applications.

Common applications for aluminum 2024-T4 include aircraft fuselage, transport vehicle parts, and wing tension members. However, product teams should note that this grade of aluminum has poor corrosion resistance and is highly sensitive to thermal shock.

Mechanical specifications:

  • Ultimate tensile strength: 200 – 540 MPa
  • Elongation at break: 14 – 20%
  • Modulus of elasticity: 71 – 73.1 GPa
  • Hardness: 70 – 120 HB
  • Maximum service temperature: 200 °C

4. Aluminum MIC 6

Aluminum MIC 6 is unique because of its specific combination of alloy and casting method that was developed for producing stable, high-tolerance plates. MIC 6 has impressive stress-relieving properties, excellent accuracy, and high machinability. Aluminum MIC 6 is also contaminant- and porosity-free. This smooth, lightweight option can be found in machining components, electronics, and even laser technology.

One drawback is that MIC 6 threads aren’t as strong as threads made from 6061, and particularly fine threads can lead to early thread failure. Product designers should keep this limitation in mind during the material selection phase.

Mechanical specifications:

  • Ultimate tensile strength: 166 MPa
  • Elongation at break: 3%
  • Modulus of elasticity: 71 GPa
  • Hardness: 65 HB
  • Maximum service temperature: 427 °C

5. Aluminum 6082

Aluminum 6082 has similar properties to aluminum 6061; however, 6082 has a slightly higher tensile strength. Further, this type of aluminum has the highest strength out of all of the 6000 series alloys and it’s exceptionally corrosion-resistant. 6082 is a good option for engineers who want more strength than what 6061 offers, but don’t want to invest in the 7000 series.

Aluminum 6082 is well-suited for general purpose applications that need an added degree of strength and toughness. This material is popular in the construction industry and can be found in many bridges, towers, and trusses. However, product designers should keep in mind that it’s difficult to produce thin walls using aluminum 6082.

Mechanical specifications:

  • Ultimate tensile strength: 140 – 340 MPa
  • Elongation at break: 6.3 – 18%
  • Modulus of elasticity: 69 – 71 GPa
  • Hardness: 35-56 HRB
  • Maximum service temperature: 130 – 150 °C

Select the right material for the job

If product teams choose to machine a part using aluminum, they can trust they’re choosing a strong, conductive, and corrosion-resistant material. Aluminum alloys 2024-T4, 7075-T6, and 6082 are best for high-performance applications, while 6061 and MIC 6 can be used in most cases in which an all-purpose aluminum will suffice.

Since CNC machining is so versatile, it can be challenging for engineers to narrow down their list of well-suited materials for a given project. With decades of technical experience, machmaster’ team of expert designers and engineers can help make material selection much easier for every product team. We are committed to helping every customer innovate and achieve their desired results throughout the entire manufacturing process — and with our expert advisory services, teams can rest assured that their material choice will fulfill all critical requirements. Contact us today — let’s make new things possible, together.

Stay tuned for more articles in the CNC material families series! In the meantime, check out the other material selection guides for processes like injection molding or 3D printing in the machmaster learning center.