Comparing Different Aluminum Alloys

Aluminum is a versatile and popular material that is used in many industries, including aerospace, automotive, and construction. However, not all aluminum alloys are created equal when it comes to machining. In this blog, we will dive deep into the different types of aluminum alloys that are commonly used in CNC machining. We will compare these alloys based on various factors such as strength, machinability, and corrosion resistance. 

What Are Aluminum Alloys?

Aluminum alloys are metal substances that are developed through a combination of aluminum and other elements such as copper, zinc, magnesium, manganese, or silicon. By adding these substances, the properties of aluminum can be altered to enhance its strength, durability, and other characteristics, making it more useful for various applications. The resulting alloys can range from lightweight and ductile to strong and rigid, depending on the specific blend of materials used. 

Why Are Aluminum Alloys Used in CNC Machining?

Aluminum alloys are a popular choice in CNC machining due to their unique properties. Their lightweight nature, combined with good strength and durability, make them an ideal material for achieving precision and consistency in machining applications. Additionally, aluminum alloys offer excellent corrosion resistance, which is particularly important when working with parts that will be exposed to harsh environments.

Comparing Different Aluminum Alloys for Machining

Each type of alloy has its strengths and weaknesses, making it important to choose the one that best suits your needs. 

Aluminum 2024

Aluminum 2024 is a high-strength alloy commonly used in aerospace applications. This alloy offers excellent machinability and can be easily welded or brazed. Its good corrosion resistance makes it suitable for outdoor applications, but it is not recommended for use in environments with high temperatures or exposure to seawater. 

When machining aluminum 2024, sharp tools and appropriate cutting speeds are crucial to prevent work hardening and ensure desired results. By selecting the right tools and techniques, aluminum 2024 can be easily machined into complex parts that require precision and durability.

Aluminum 5052

Aluminum 5052 is a popular alloy for machining due to its high strength and good corrosion resistance. This alloy is commonly used in marine and automotive applications, thanks to its excellent forming capabilities that make it easy to shape into complex parts. 

Aluminum 5052 is also weldable and has good machinability, allowing for precise cuts and finishes. However, it can be prone to cracking if not properly annealed before machining. Therefore, it’s crucial to ensure proper annealing of the alloy before beginning the machining process for optimum results.

Aluminum 6061

Aluminum 6061 is a versatile and popular choice for machining projects. This alloy has an excellent strength-to-weight ratio and good machinability, making it suitable for various applications. 

Additionally, aluminum 6061 can be easily welded and brazed, making it a preferred option in the manufacturing industry. Its corrosion resistance also makes it an ideal choice for outdoor or marine applications. When machining aluminum 6061, it’s essential to choose appropriate cutting speeds and feeds while selecting the right tools and geometry to ensure optimal performance.

Aluminum 7075

Aluminum 7075 is a high-strength alloy that is widely used in the aerospace and automotive industries due to its excellent mechanical properties. Its strength, toughness, and fatigue resistance make it ideal for applications where high stresses are expected. 

However, machining this alloy can be challenging without the right tools and techniques. Proper coolant and lubrication are crucial when machining Aluminum 7075 to prevent cracking or damage to the material. Despite these challenges, this alloy’s excellent machinability and corrosion resistance make it a top choice for many industries.

Factors to Consider When Choosing an Aluminum Alloy for Machining

Strength and Durability

Higher strength and durability are often desired but can make machining more difficult, requiring specialized tools and techniques. Common high-strength alloys like 7075 and 2024 aluminum may be harder to machine, while lower-strength alloys like 6061 may be easier but not suitable for all applications. 


The machinability of an aluminum alloy is determined by its hardness, ductility, and thermal conductivity. High-machinability aluminum alloys like 6061, 7075, and 2024 are ideal for machining as they require less energy to machine and are easier to work with.

Corrosion Resistance

Corrosion can pose a significant problem for metal parts used in harsh environments or exposed to outdoor conditions. An aluminum alloy with high levels of corrosion resistance is crucial for ensuring the longevity and reliability of machined parts. Aluminum alloys such as 6061 and 7075 are ideal choices due to their excellent resistance to corrosion, making them suitable for use in marine and aerospace applications. 

However, it’s important to note that some alloys with increased strength and hardness may have lower corrosion resistance, so it’s essential to consider the specific application and environment when selecting the appropriate aluminum alloy for machining.

Best Practices for Aluminum Machining with Different Alloys

When it comes to aluminum machining, understanding the properties of different alloys is essential for achieving optimal results. One best practice is to carefully select the appropriate tooling and machining techniques for each specific alloy. By following these best practices, you can achieve successful results when working with different aluminum alloys.

Cutting Speeds and Feeds

Different aluminum alloys have unique properties that affect their machinability, including thermal conductivity and hardness. These properties determine the cutting speed and feed rates best suited for each alloy. It’s essential to adjust the cutting speeds based on the specific alloy being machined to achieve optimal results. 

Harder alloys require slower cutting speeds and higher feeds to prevent tool wear and damage, while softer alloys can be machined at higher speeds with lower feeds for increased efficiency. Consult with a machining expert or reference materials for specific guidelines on cutting speeds and feeds for each aluminum alloy.

Tool Selection and Geometry

The right tool selection and geometry play a crucial role in successful aluminum machining. Different aluminum alloys require different tooling and geometry due to their unique properties. 

For instance, aluminum 6061 demands sharp tools with a positive cutting edge, whereas aluminum 7075 needs specialized tools with a high rake angle. Tool geometry factors such as clearance angle, relief angle, and nose radius also affect performance. Selecting the right tools and geometry for the specific aluminum alloy being machined can improve the efficiency and quality of the finished product. 


Choosing the right aluminum alloy for your CNC machining project is crucial to its success. Different alloys have different properties and characteristics that make them suitable for specific applications. By understanding these differences and considering factors such as strength, machinability, and corrosion resistance, you can choose the best alloy for your needs. 

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