Aluminum Alloy Types for CNC Machining Parts: Grades, Cost, Selection & Applications

 

 

 

While there are so many aluminum grades on the market, most of CNC machined aluminum parts utilize the grades that should match the budget and use conditions. Selecting the wrong grade can lead to unexpected machining costs, poor anodizing results, or premature component failure. Thus, for design or production of custom aluminum products, choosing the right aluminum grade is a balancing act between mechanical strength, surface finish, manufacturability, and total production cost.

 

This guide breaks down the most common aluminum alloy types for custom machining, compares their costs and applications, and provides practical engineering solutions for common aluminum part requirements. The final case study will demonstrate how we address a client requirement to balance both the aesthetic appearance and mechanical strength of high-strength exterior structural components.

 

 

 

 

How to Identify Aluminum Alloy Grades?

 

 

 

 

 

Aluminum is one of the most versatile materials in the manufacturing industry, offering a unique combination of light weight, strength, and corrosion resistance. These properties make it ideal for a wide range of applications, from aerospace to consumer goods. But for different series of aluminum alloys (1000–8000 series), they show some differences based on their primary alloying elements.

 

Aluminum alloy grades are identified using a four-digit numerical system established by the Aluminum Association. The first digit indicates the major alloying element, while the remaining digits represent specific variations within that alloy series. For example, in the grade 6061, the "6" indicates that the alloy belongs to the 6xxx series, where magnesium and silicon are the primary alloying elements. The "061" identifies the specific alloy composition within this series. Here’s a table to help you identify aluminum alloy grade series:

 

 

 

 

 

 

While all series have their place, some special grade(2024, 5052, 6061, 6063, 7075 ) account for most of precision CNC machined components. In the next section, we will analyze the total production costs associated with these core grades and how they impact your manufacturing budget.

 

 

 

 

What You Should Know about the Cost? Production of Different Aluminum Grade Parts    

 

 

 

 

When budgeting for custom aluminum parts, you may focus on aluminum grade raw material prices, tool wear, machining time (cycle time), and scrap rate.

 

 

 

 

 

 

 

 

Balance the Cost, Aesthetic, and Functional Requirements

 

 

 

1. AL 6061 (Cost-Effective for Most Common CNC Machined Parts)

 

 

For everyday CNC machined parts prioritizing cost-efficiency, 6061 aluminum is the most popular and versatile choice. It strikes the ideal balance between low material cost, high machining speeds, and excellent anodizing performance, making it the go-to baseline for most structural and cosmetic components.

 

 

 

 

 

2. AL 6063 (Economical Choice for Extrusions & Complex Profiles)

 

 

When a project involves extruded shapes or requires superior cosmetic surface finishes, 6063 aluminum is the ideal choice for balancing cost and aesthetics. While raw material costs are slightly higher than 6061, its smooth surface response to architectural anodizing makes it cost-effective for heat sinks, enclosures, and framing.

 

 

 

 

 

 

3. AL 5052 (Budget-Friendly Option for Corrosion & Sheet Metal)

 

 

For formed sheet metal parts or saltwater environments, 5052 aluminum offers a budget-friendly corrosion-resistant solution. Although its gummy nature can slightly increase secondary deburring labor during CNC milling, it delivers exceptional cost savings for marine hardware and bent enclosures.

 

 

 

 

 

4. AL 2024 (High-Performance Investment for Fatigue Resistance)

 

 

For parts subjected to severe cyclic stress, 2024 aluminum is a high-performance alloy worth the extra investment. High copper content increases raw material price and tool wear, but its exceptional strength-to-weight ratio and fatigue resistance justify the cost in high-stress aerospace components.

 

 

 

 

 

5. AL 7075 (Premium Choice for Extreme Mechanical Strength)

 

 

When high mechanical strength cannot be compromised, 7075 aluminum is the premium high-performance option. Although raw material and machining time costs can double those of 6061, its steel-like strength is essential for critical aerospace, defense, and high-performance racing parts.

 

 

 

 

 

 

 

Key Physical and Mechanical Table of Key Aluminum Grades

 

 

Here is the technical comparison table detailing the key physical and mechanical properties of the primary CNC machining aluminum alloys:

 

 

 

 

 

 

 

Applications of Aluminum Alloy Grades

 

 

Aluminum alloys are used across a wide range of industries due to their versatility and unique properties:

 

 

Aerospace Industry: Aluminum alloys, particularly those in the 2xxx and 7xxx series, are extensively used in the aerospace industry for manufacturing aircraft structures, fuselages, and engine components. Their high strength-to-weight ratio and corrosion resistance make them ideal for aerospace applications.

 

 

 

 

 

Healthcare Industry: In the healthcare industry, aluminum alloys are used to manufacture medical devices, surgical instruments, and diagnostic equipment. Their lightweight, corrosion resistance, and ease of sterilization make them suitable for these critical applications.

 

 

Automotive Industry: The automotive industry relies on aluminum alloys, especially the 5xxx and 6xxx series, for manufacturing lightweight yet strong components such as engine blocks, transmission housings, and body panels. The use of aluminum alloys in vehicles contributes to improved fuel efficiency and reduced emissions.

 

 

 

 

Electrical and Electronic Engineering: Aluminum alloys are widely used in electrical and electronic engineering for producing components like heat sinks, power cables, and housings for electronic devices. Their excellent electrical and thermal conductivity, combined with lightweight properties, make them indispensable in this field.

 

 

 

 

 

Consumer Goods: Aluminum alloys are also prevalent in consumer goods, including cookware, sporting equipment, and household appliances. Their durability, lightweight, and resistance to corrosion make them ideal for everyday products.

 

 

 

 

 

 

 

 

Advantages and Limitations of Common Machining Alloys

 

 

To help you further evaluate the trade-offs for your specific design, here is a detailed breakdown of the advantages, limitations, and primary applications for each major CNC machining aluminum alloy.

 

 

Aluminum 6061-T6

 

• Pros: Highly versatile, highly machinable, easy to weld, yields superior color anodizing results.

• Cons: Lower tensile/yield strength compared to 7000-series alloys.

• Best For: Enclosures, robot arms, automotive brackets, custom CNC prototypes.

 

 

Aluminum 6063-T6

 

• Pros: Exceptional extrudability, superior smooth surface finish, excellent anodizing response, good corrosion resistance.

• Cons: Lower tensile and yield strength than 6061; slightly softer, which requires sharp tooling to prevent burring during milling.

• Best For: Heat sinks, architectural frames, custom extruded profiles, decorative trim, electronic enclosures.

 

 

Aluminum 5052-H32

 

• Pros: Excellent corrosion resistance (especially salt water), high workability, easily bendable.

• Cons: Not ideal for tight-tolerance precision CNC milling due to its soft nature.

• Best For: Marine hardware, fuel tanks, custom sheet metal enclosures.

 

 

Aluminum 2024-T3

 

• Pros: Exceptional fatigue resistance, high strength-to-weight ratio, excellent structural performance under cyclic stress.

• Cons: Higher material cost, poor corrosion resistance (often requires cladding or protective coating), reduced weldability, higher tool wear during machining.

• Best For: Aircraft fuselage structures, wing tension members, high-vibration automotive components, high-stress fasteners.

 

 

Aluminum 7075-T6

 

• Pros: Exceptional strength-to-weight ratio, superior fatigue resistance, high hardness.

• Cons: Higher material cost, harder to machine, poorer corrosion resistance than 6000-series, color anodizing often results in darker, muddy tones.

• Best For: Aerospace fittings, high-stress gears, defense components, racing parts.

 

 

 

 

Considerations for Choosing the Right Type of Aluminum Alloy

 

 

When selecting the right aluminum alloy for a project, several factors must be considered:

 

• Machinability Ratings: The machinability of an aluminum alloy affects the ease and speed of CNC machining. Alloys with higher machinability ratings, like 6061 and 6063, are preferred for precision CNC machining parts.
• Material Cost and Availability: The cost and availability of the alloy can influence the choice, especially for large-scale production. While high-performance alloys like 7075 offer superior strength, they are also more expensive and may not be readily available.
• Heat Treatment: Some aluminum alloys(e.g., 6061, 7075) require heat treatment to achieve their full strength potential. Understanding the heat treatment requirements and how they affect machinability and final properties is crucial for making the right alloy choice.

 

 

 

 

VMT CNC Machining Factory Case Study

 

 

 

 

Balancing Strength & Anodizing Color Uniformity for Exterior Structural Parts

 

 

An industrial automation client required a batch of high-strength exterior structural brackets for an outdoor robotic housing. The part was exposed to both heavy mechanical loads and environmental elements. The engineering drawing specified AL 7075-T6 to handle high shock loads, paired with a vibrant blue color-anodized finish. However, samples produced by the client's previous supplier consistently failed to meet their aesthetic color standards, leading them to reach out to us for a practical manufacturing solution.

 

 

The Challenge: Color anodizing AL 7075-T6 inherently produces dark, muddy tones and batch variation because of its high copper content.

 

 

To address this issue, our engineering team presented two practical solutions:

 

• Option A (Keep AL 7075-T6): Retain the high-strength alloy, but replace anodizing with powder coating or painting to achieve a bright, uniform color without interference from the underlying material.

• Option B (Switch to AL 6061-T6): If the structural loads allow, switch to AL 6061-T6 with color anodizing, which achieves an ideal cosmetic finish while reducing material and machining costs.

 

The client chose Option A to guarantee maximum mechanical strength for their outdoor robotics. To execute this seamlessly, we conducted high-precision 5-axis CNC milling on the 7075-T6 brackets, maintaining tight dimensional tolerances of ±0.02 mm. Before coating, the parts underwent a thorough chemical degreasing and light sandblasting (120-mesh glass beads) to optimize surface adhesion. We then applied a high-durability electrostatic blue powder coating followed by precision thermal curing at 180°C, ensuring a tough, weather-resistant layer with a uniform thickness of 60–80 µm.

 

 

The final delivered parts achieved 100% color consistency across the entire 500-piece batch, passed a 1,000-hour salt spray corrosion test (ASTM B117), and successfully maintained the original tensile strength requirement of 572 MPa, delivering a fully optimized component on time.

 

 

 

 

 

Get Aluminum Machining Solutions at VMT

 

 

At VMT, we specialize in precision CNC machining of aluminum alloys, offering custom CNC machining services to meet the unique needs of our clients. Whether you need high-strength components made from 7075 aluminum or corrosion-resistant parts from 5052 aluminum, our state-of-the-art CNC machining factory is equipped to deliver high-quality results. Our experienced team can assist you in selecting the right aluminum alloy for your project, ensuring optimal performance and efficiency.

 

 

 

 

 

 

Conclusion

 

Aluminum alloys are essential materials in modern manufacturing, offering a balance of lightweight properties, strength, corrosion resistance, and machinability. By understanding the different types of aluminum alloys and their characteristics, manufacturers can make informed decisions to enhance the performance and longevity of their products. Whether you’re working in aerospace, automotive, or consumer goods, selecting the right aluminum alloy is crucial for achieving the best results in CNC machining.

 

 

FAQs

 

 

What is the most cost-effective aluminum grade for CNC machining?

 

 

AL 6061-T6 is the most cost-effective grade. It offers an ideal balance of low raw material cost, fast machining speeds, and widely available stock sizes.

 

 

Can you anodize 7075 aluminum in bright colors?

 

 

Yes, but the results are rarely as vibrant or consistent as 6061. Because 7075 contains high levels of zinc and copper, color anodizing often yields darker or slightly uneven hues. For strict cosmetic requirements, clear or black anodizing is recommended for 7075.

 

 

Which aluminum alloy is best for corrosion resistance in marine environments?

 

 

AL 5052 and AL 6061 offer superior corrosion resistance in saltwater conditions. AL 5052 is typically preferred for sheet metal components, while AL 6061 is preferred for CNC precision machined parts.

 

 

Which Aluminum Alloy is Better for Machinability, 6061 or 7075?

 

 

6061 aluminum is better for machinability, offering easier cutting and better surface finish, making it ideal for general-purpose machining. 7075, while stronger, is more challenging to machine.

 

 

What is the Difference Between 5052 and 6061 Aluminum?

 

 

5052 aluminum offers superior corrosion resistance and is more suited for marine applications, while 6061 aluminum provides better strength and machinability, making it more versatile for structural applications.

 

 

What is the Difference Between 6061 and 7075 Aluminum?

 

 

6061 aluminum is more versatile with good strength, machinability, and corrosion resistance, while 7075 aluminum offers higher strength and fatigue resistance, making it ideal for high-stress applications like aerospace components.

 

 

What Is the 5000 Series Aluminum Alloy?

 

 

The 5000 series aluminum alloys are primarily alloyed with magnesium, offering excellent corrosion resistance and moderate strength, making them ideal for marine and chemical applications.

 

 

What Is the Difference Between 4000 and 5000 Aluminum?

 

 

The 4000 series aluminum alloys are primarily alloyed with silicon, used mainly for welding and brazing applications, while the 5000 series are alloyed with magnesium, providing better corrosion resistance and weldability.

 

 

 

 

Disclaimer

 

 

The technical information and manufacturing advice shared on the VMT website are for general guidance only. While we strive for accuracy, VMT does not guarantee that the processes, tolerances, or material properties mentioned are applicable to every specific project. Any reliance you place on such information is strictly at your own risk. It is the buyer's responsibility to provide definitive engineering specifications for any production orders. Final specifications and service terms shall be subject to the formal contract or quotation confirmed by both parties.