CNC machining is one of the most versatile manufacturing processes available today. This process is compatible with various materials. Aluminum is among the most popular material choices for CNC machining applications. CNC machining aluminum alloys provide manufacturers huge flexibility for product manufacturing.
However, narrowing down your options when it comes to aluminum machining can be daunting. In this article, we give you all the necessary details on top aluminum alloys for CNC machining. We would also explain some key benefits of aluminum machining and why it is widespread across various industries.
What is Aluminum Machining?
Aluminum machining is simply the process involving the use of aluminum alloys in product manufacturing. Aluminum CNC machining employs computer software and other compatible equipment to move machine tools across the surface of aluminum materials.
This process results in highly accurate and high-precision machined parts. The availability of numerous grades of aluminum and its high machinability makes it very useful in machining applications. Its low cost also makes it ideal for prototyping and custom tooling.
Aluminum Alloys and Their Classifications
Commercially available aluminum for CNC machining projects is not pure. Aluminum itself is a soft metal. Therefore, alloying elements help make aluminum sheet, plate, thin foil and bar product. These elements give hardness and strength to the aluminum.
There are thousands of aluminum alloys available. However, some variants are more valuable than others. The most common alloys are classified into series according to their main alloying element. Each of these series possesses similar properties. They include the following:
Aluminum Alloy Series 1xxx
The 1xxx series contains 99% pure aluminum by weight. Members of the 1xxx series are highly ductile with high thermal and electrical conductivity.
Therefore, they are mainly used in the electrical industry. They are also the softest grades, making them highly formable with low mechanical properties and excellent corrosion resistance.
Aluminum Alloy Series 2xxx
The major alloying element in this series is copper. Thus, many people refer to them as “copper alloys.” The 2xxx series has excellent machinability with similar mechanical properties as mild steel. The addition of copper to this alloy series gives them poor corrosion resistance. They are popular choices in making aerospace parts.
Aluminum Alloy Series 3xxx
The 3xxx series boasts excellent formability, thanks to manganese – the main alloying element. Generally, these aluminum alloys cannot be heat treated. Thus, they are ideal as general-purpose alloys for moderate-strength applications.
Aluminum Alloy Series 4xxx
Silicon is the primary alloying element in the 4xxx series. This element lowers its melting point significantly. However, it does not cause brittleness. The unique characteristics of this series make them useful in welding wire. They are also often appealing options for architectural applications.
Aluminum Alloy Series 5xxx
The major alloying elements in the 5xxx series is magnesium and manganese. These elements ensure excellent formability and high tensile strength. Alloys in this grade are also corrosion-resistant.
They are primarily used for marine and transportation applications. A typical example is Aluminum 5083.
Aluminum Alloy Series 6xxx
This is the most versatile series of aluminum alloys. Magnesium and silicon are their major alloying elements, and they can be heat treated. A popular member of the class is the Aluminum 6061 alloy, which comes in sheets, plates, and extrusions.
It has excellent formability and increased corrosion resistance. At the same time, it offers medium strength. The versatility of this series makes them useful in electrical components, piping, architectural parts, and consumer goods.
Aluminum Alloy Series 7xxx
The 7xxx series is popular for strength, containing zinc as the primary alloying element. It also contains a good amount of copper, chromium, and magnesium. The strong aluminum alloys in the 7xxx series are popular for aerospace applications due to their high strength.
Most Common Aluminum Alloys for Aluminum Machining
While there are plenty of options to choose from, only a few aluminum alloys are effective for CNC machining. From our experience, here are the four most popular aluminum alloys for aluminum machining:
1. Aluminum 6061-T6
This alloy is among the most popular options on the market, belonging to the 6xxx series. Most manufacturing companies offer 6061-T6 as the standard aluminum grade for CNC machining.
It is very versatile, easily machinable, and has various heat treatments. This all-purpose material is applicable in an extensive array of applications. However, it is not ideal for high-stress applications despite its excellent strength-to-weight ratio.
Some of the typical applications of aluminum 6061-T6 include automotive parts like bicycle frames, chassis, and valves. Other applications are found in computer parts and electronics.
2. Aluminum 7075-T6
Engineers who need alloys for high-performance and high-stress applications should consider 7075-T6. This aluminum grade is popular for its good strength-to-weight ratio. You can even compare its hardness to that of some milder steel.
However, there are some drawbacks to this allow. It is less resistant to corrosion and less ductile than most other grades. Aluminum 7075-T6 can also be relatively more expensive in some production cases.
This alloy has an extensive range of applications in the aerospace and military industries. Some metal parts produced include aircraft fittings, fuse parts, missile arts, etc. Other applications include mold tool manufacturing, bicycle parts, hand glider, golf clubs, rock climbing equipment, and more.
3. Aluminum 6082-T6
The forming of this alloy is typically by rolling and extrusion. It also has similar properties as the 6061 alloy in the same series. However, aluminum 6068-T6 is slightly stronger – the strongest alloy in the 6xxx series.
It also has good thermal conductivity and excellent weldability. Its high strength and exceptional resistance to corrosion make it a great option for several applications.
You will find it in towers, bridges, and other construction works. However, it will be best for product designers to note that it is difficult to make thin walls with this alloy.
4. Aluminum 5083-T6
5083-T6 aluminum is renowned for its excellent performance in extreme conditions. This aluminum grade is very resistant to corrosion in marine and chemical environments.
It boasts of the highest strength of the non-heat-treatable alloy. 5083 excels in applications with low temperatures, and it is not for use in temperatures over 65°C.
Due to its desirable characteristics, the cryogenic market has wide use for the 5083 alloy. It is also very suitable for marine applications, chemical applications, transport vehicle parts, pressure equipment, and more.
The table below summarizes the essential mechanical specifications of the alloys discussed above.
| Aluminum Alloy | Ultimate Tensile Strength | Elongation At Break | Modulus of Elasticity | Hardness | Maximum Service Temperature |
| 6061-T6 | 310 MPa | 17% | 68.9 GPa | 60 HRB | 130 – 150 °C |
| 7075-T6 | 434-580 MPa | 10-15% | 69-76 GPa | 79-86 HRB | 100°C |
| 6062-T6 | 140-340 MPa | 6.3-18% | 69-71 GPa | 35-56 HRB | 130-150°C |
| 5083-T6 | 270-350 MPa | 13% | 68-72 GPa | 74 HV | 80-100°C |
Use of Aluminum Alloy Chart in Aluminum Machining
It is not enough for you to know the different aluminum alloys available for machining. Instead, proper knowledge of their machinability will help you choose the suable type for your applications. Some of the factors you should consider include:
- Machinability
- Formability
- Weldability
- Corrosion Resistance
- Strength
- Suitable Applications
To save you the trouble, the picture below contains a table that summarizes the properties of available alloys for quick reference. Take a look:
Benefits of Aluminum CNC Machining
The fundamental benefits of using aluminum for the machining process apply to all the alloys. These unique advantages make them suitable for CNC milling and other manufacturing processes. They include:
Machinability
Engineers choose aluminum for CNC machining because it is easy to machine. Aluminum is soft and chips easily, so it can be easily and quickly cut by CNC machines cutting tools. This feature is very beneficial to machinists and customers ordering aluminum parts.
The ease of shaping complex parts makes the job faster, leading to a less expensive process. Moreover, CNC milling machines can easily meet tight tolerances for accuracy and repeatability.
Corrosion Resistance
Aluminum grades have different resistance to corrosion. However, the most popular ones used for CNC machined aluminum parts are exceptionally corrosion resistant in atmospheric and marine conditions. A typical example is aluminum 6061.
Furthermore, the anodization potential of these alloys makes them more corrosion resistant. That is, applying aluminum anodizing surface finish will increase their resistance to corrosion.
Strength-To-Weight Ratio
The mechanical properties of aluminum make it ideal for mechanical applications. Despite being lightweight, this material has very high strength.
A combination of both characteristics describes the strength-to-weight ratio. The high strength-to-weight ratio of aluminum makes it ideal for automotive and aerospace parts.
Electrical Conductivity
CNC machined aluminum parts are helpful in making electrical and electronics components, thanks to their ability to conduct electricity. Aluminum materials are often more conductive than stainless steel, having about 37.7 million siemens per meter of conductivity at room temperature.
Recyclability
Another crucial benefit of aluminum is that it is highly recyclable. CNC machining is a subtractive process, generating several chips as waste materials. The recyclability of aluminum helps to reduce material waste. At the same time, it helps those who might want to recoup part of their expenditure.
Conclusion
Aluminum machining is widely used due to the properties and benefits of aluminum. CNC machining aluminum alloys make the process even more seamless.
This article described the common aluminum alloys for machining and their various properties. Understanding this will help you make informed decisions while selecting an alloy for your manufacturing process.
However, it is always best to have professional hands working with you. AT’s team of experienced and highly-skilled engineers and designers are always ready to make material selection easier for your product team. We aim to help you achieve the best machining results.
Contact us today, and let’s bring your ideas to life!
