Cast Plate
Aluminum is one of the most highly sought-after CNC materials, as it’s well-suited for creating custom metal parts and prototypes such as brackets, base plates, and heat sink enclosures. Aluminum offers excellent machinability and can be heat-treated to high strength and hardness. However, no two alloys of aluminum are the same. It is often a challenge for manufacturers and fabricators to identify the most suitable aluminum for CNC machining without compromising end quality or exceeding budget.
Below, we briefly discuss some of the most commonly used CNC aluminum alloys and learn about their favorable properties and application areas.
Common CNC Aluminum Alloys
Choosing the right grade aluminum for CNC machining involves analyzing several factors in parallel, such as tensile strength, corrosion resistance, weldability, machinability, and workability. Each grade has been metallurgically engineered for some specific application areas.
Let’s analyze some highly popular aluminum alloys that undergo CNC processes such as milling, turning, and multi-axis machining to produce useful machine parts and prototypes for various industries.
6061
6061 is one of the most widely used aluminum alloys. It is lightweight and offers a clean surface finish. It’s also much easier to machine and weld than 7075 for a wide range of structural applications. 6061 is mostly preferred for corrosion-prone low-budget applications where frequent welding is required. This explains why manufacturers consider 6061 as the go-to aluminum for most machine parts. However, not all 6061 alloys carry similar properties. Thus, understanding the machining properties of different 6061 aluminum grades is essential for choosing the right grade for CNC machining parts for the end application.
Applications:
- Aircraft parts
- Structural parts
- Cylinder heads
- Pipes
- Electronics
- Recreation equipment
6082
6082 offers excellent corrosion resistance and exhibits the highest strength amongst all 6xxx series alloys; therefore, it’s an ideal alternative to 6061 alloys and is best suited for stressed applications. However, because it’s available in different grades, it’s important to select the grade appropriate for the end application. For instance, the most popular L grades (L111, L113, L114, L115) are used in aerospace and military applications.
Applications:
- Trusses
- Bridges
- Cranes
- Transport applications
7075
Zinc is the primary alloying element in 7075; thus, it offers the highest strength-to-weight ratio compared to any other aluminum alloy and is twice that of 6061 alloys. 7075 is widely used for aircraft and aerospace applications. However, the mechanical properties vary by temper. The T6 temper has the highest strength but the lowest stress corrosion resistance; therefore, in high-stress applications, the T73 or T76 alloys are more suitable. A local metal supplier can assist you in selecting the right temper of 7075 depending on the end application.
Applications:
- Gears
- Shafts
- Valves
- Mould tool
- Missile parts
2024
2024-T4 exhibits an exceptional strength-to-weight ratio coupled with high fatigue resistance, thus it’s suitable for aerospace applications. However, it is highly susceptible to environmental corrosion. Though 2024 alloys can be forged and hot worked (T3, T4, and T8 tempers), they are not ideal for welding and soldering.
Applications:
- Commercial & military aircraft
- Automotive components
- Structural parts
- Electronics
| Science Fact: Aluminum is so lightweight and durable that it’s used in making the outer shells of spacecraft. |
5052
5052 is a medium- to high-strength alloy from the 5xxx series, with a strength slightly higher than 5251 alloys. The H32 hardened 5052 aluminum alloy offers excellent corrosion resistance to caustic environments in the absence of copper from its configuration. Additionally, the high concentration of magnesium offers corrosion resistance from toxic chemicals, such as concentrated nitric acid, ammonia, and ammonium hydroxide. Though 5052 alloys cannot be heat-treated like 7075 or 6061 alloys, they can be cold worked to increase their strength.
Applications:
- Pressure vessels
- Kitchen appliances
- Hydraulic tubes
- Small boats
- Electronic chassis, tubes
5080
5080 is a homogenized and stress-relieved aluminum cast plate for high precision applications. It is a low-cost alternative to MIC-6, yet it comes with a very fine grain porosity-free structure. As a result, 5080 offers predictable tolerances and excellent dimensional stability. Also, it allows you to work with thinner plates to optimize costs and save processing time.
Applications:
- PCB substrate
- Gages
- Fixtures
- Molds
- High precision machined components
MIC-6
MIC-6 is a 7xxx series aluminum alloy with zinc as its major alloying element. As a cast product, it is fully stress-relieved and allows for high-speed metal removal with little to no distortion, unlike other long-grained metal alloys. MIC-6 can be considered an ideal replacement to 6061 when high strength is not the primary requirement.
The granular cast structure contributes to its improved dimensional stability and smooth flatness tolerance as compared to 6061 alloys. When machined, MIC-6 produces small, uniform chips and offers good weldability and high resistance to corrosion cracks.
Applications:
- Tooling
- Base plates
- Jigs and fixtures
- Optical industry
Anodizing Options for CNC Machined Aluminum Parts
In CNC machining, especially when machining aluminum, anodizing is a crucial finishing process that enhances the mechanical properties and appearance of aluminum parts. Among the different types of anodizing for aluminum CNC machining, there are three that stand out.
- Type I-chromic acid anodizing: Often used in the aerospace industry, this type provides a thin yet durable coating, making it ideal for welded parts and assemblies. It’s a primer choice before painting due to its non-conductive nature and adds to the corrosion-resistant qualities of the aluminum grade.
- Type II-sulfuric acid anodizing: This type is harder than Type I and is commonly used in consumer products and automotive parts. Its durability makes it suitable for items like motorcycle parts and hydraulic valve bodies, where a balance of strength-to-weight ratio is crucial.
- Type III-hard anodize or hardcoat: Known for providing the thickest and hardest coating, it’s widely used in heavy-duty applications with high wear resistance. This type is ideal for automotive, military, and marine applications, enhancing the aluminum’s strength and durability.
These anodizing types are integral to the CNC aluminum machining process, enhancing the aluminum’s corrosion resistance and strength, which is vital for the manufacturing process. CNC machines using the right cutting tool can significantly benefit from these anodizing methods, ensuring the longevity and performance of CNC aluminum machining components.
Here’s a comparison table to illustrate the differences between the anodizing types used in CNC machines:
| Anodizing Type | Application | Benefits |
| Type I-Chromic Acid | Aerospace, Welded Parts | Thin coating, Non-conductive, Primer for painting |
| Type II-Sulfuric Acid | Automotive, Consumer Products | Durable, Suitable for high wear parts |
| Type III-Hard Anodize | Heavy-duty (Automotive, Military) | Thickest and hardest coating, High wear resistance |
By understanding these types in aluminum CNC machining, manufacturers can optimize the machining process and choose the best anodizing method based on the intended use and required mechanical properties of the CNC machining aluminum parts.
Purchase Aluminum for CNC Machining from a Reliable Metal Supplier
Industrial Metal Service has been supplying and recycling metals in the San Francisco Bay Area and nationwide for more than two decades. Our inventory includes a wide range of popular grades of aluminum, including 6061, 5080, and MIC-6, cut-to-size for immediate CNC machining requirements. We also supply other metals, such as titanium, steel, and copper.