Machining Brass vs Aluminum: The Advantage of Tradition

Humans have been producing and using brass, one of the oldest alloys, for millennia. Its workability, hardness, corrosion resistance, and attractive appearance made it a staple of ancient metallurgy for both practical and decorative purposes.

Humans have been using aluminum for a much shorter time than brass, but its incredible properties, especially its strength-to-weight ratio, have made it one of the most commonly used metals in the world.

In terms of machining, brass and aluminum both perform well. Even though brass has existed for much longer than modern CNC machining processes, its mechanical properties make it perfect for machining, even in home shops that may not have expensive industrial equipment.

In this post, we’ll look at some of the characteristics of brass that make it a great choice for machining, then we’ll go over some guidelines for CNC machining brass vs. aluminum.

Best Brass and Aluminum Grades for CNC Machining

CNC machining is a gentle art. Selecting the right material grade can significantly impact your project’s success. Here, we’ll explore the best brass and aluminum grades for CNC machining, focusing on their unique properties and ideal applications.

Best Brass Grades for CNC Machining

Brass is a favorite among machinists because it’s easy to work with. However, choosing the right brass alloy is important to get the best results. Here are some of the top brass grades for CNC machining to consider:

• C360 (Free-Cutting Brass): This is the gold standard for brass CNC machining. C360 brass, often referred to as free-cutting brass, contains a higher percentage of lead, making it incredibly easy to machine. It’s perfect for brass parts that require intricate details and a smooth finish. This grade is ideal for various applications, such as fittings, gears, and decorative hardware.
• C353 (Engraver’s Brass): If you’re working on decorative pieces, such as plaques, nameplates, or jewelry, C353 is your go-to. It has a fine-grain structure, which makes it great for engraving and etching. Plus, it polishes up beautifully, giving your finished product a high-quality look. This makes it a top choice among brass grades for CNC machining.
• C385 (Architectural Bronze): For projects where strength and durability are key, C385 is a solid choice. It’s commonly used in architectural applications and hardware. It’s tougher than C360 but still offers good machinability, making it suitable for structural components and heavy-duty brass parts.

Brass, an alloy of copper and zinc, is also valued for its good corrosion resistance, making it suitable for a wide range of brass machined parts. However, machinists must be aware of stress corrosion cracking, a common issue in brass components, especially when exposed to certain environments.

Best Aluminum Grades for CNC Machining

Aluminum is another popular choice for CNC machining, prized for its lightweight properties and excellent machinability. Here are some of the best aluminum grades for CNC machining that machinists swear by:

• 6061: This is probably the most commonly used aluminum alloy. It’s versatile, strong, and offers good corrosion resistance. 6061 aluminum is perfect for various applications, from aerospace components to bike frames. Its ease of machining makes it a favorite for both prototypes and production runs.
• 7075: If you need something tougher, 7075 aluminum is the way to go. Known for its high strength-to-weight ratio, this grade is often used in high-stress applications like aerospace and military projects. It’s not as easy to machine as 6061, but its strength makes it worth the effort for critical parts.
• 2024: Another high-strength aluminum alloy, 2024 is great for applications that require a high level of fatigue resistance. It’s often used in aircraft structures and automotive parts. While it’s a bit more challenging to machine due to its strength, the durability of the end product makes it a popular choice.

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Essential Tips and Techniques for Aluminum and Brass CNC Machining

Aluminum and brass are popular choices for CNC machining, but each has its own quirks. Learn the best ways to machine these metals to get the job done fast and produce top-notch parts. Here are some critical aspects to keep in mind while machining brass and aluminum.

Machining Brass Alloys

Brass is a beloved material in the machining world thanks to its ease of use and attractive finish. However, to make the most of your brass CNC machining process, there are a few critical tips and techniques to keep in mind.

Managing Heat and Tarnishing

• Heat management: Brass can generate a lot of heat during machining, which can lead to work hardening. To mitigate this, use lower spindle speeds (around 300-400 RPM) and light depths of cut. This helps in maintaining the properties of brass alloys.
• Tarnish prevention: Brass tarnishes quickly when exposed to air. Apply a protective coating or polish the surface immediately after machining to maintain its appearance.

Optimizing Tool Selection

• Non-ferrous specific tools: Using tools designed specifically for non-ferrous metals, such as carbide or cobalt bits, can result in cleaner cuts and longer tool life, which is crucial for brass CNC machining.
• Thread Forming Taps: For threading brass, opt for thread forming taps instead of standard taps to reduce the risk of damaging the threads, an essential step in the CNC brass machining process.

Effective Lubrication

• Cutting Fluids: Utilizing a high-quality cutting fluid can greatly improve the surface finish and extend tool life. It helps in dissipating heat and reducing friction, which is crucial for brass components.

Workholding Techniques

• Firm Securing: Properly securing the brass workpiece is essential to avoid vibration and chatter, which can negatively impact the surface finish of your brass parts. Use a stable fixture or vise to hold the material securely.

Brass, an alloy of copper and zinc, is widely used for decorative hardware, fittings, and engraved pieces.

Its excellent corrosion resistance makes it suitable for various applications, but be mindful of stress corrosion cracking, especially in environments with ammonia or moisture.

Understanding the properties of brass alloys can help in selecting the right material for specific applications in brass CNC machining.

Machining Aluminum

Aluminum is a versatile material that is highly valued in CNC machining for its lightweight and excellent machinability. However, achieving the best results with aluminum requires specific techniques and considerations.

Managing Heat and Chip Formation

• High spindle speeds: Aluminum benefits from higher spindle speeds (800-1200 RPM) due to its lower melting point. This helps in producing fine chips and reduces the risk of chip welding.
• Effective chip Removal: Ensure your CNC machine has efficient chip removal systems to prevent chips from re-welding onto the workpiece.

Tool Selection and Maintenance

• Sharp Carbide Tools: Using sharp carbide tools can prevent built-up edge (BUE) and produce a cleaner finish. Regularly check and replace tools to maintain cutting efficiency.
• Coolant Usage: Flood coolant is highly recommended when machining aluminum. It helps in cooling the tool and workpiece, preventing thermal expansion and ensuring a consistent finish.

Workholding and Vibration Control

• Stable Workholding: Like brass, aluminum also requires stable workholding to minimize vibration and chatter. Use soft jaws or fixtures that can securely hold the workpiece without deforming it.
• Vibration Dampening: Implement vibration dampening techniques, such as using damping compounds or supports, to enhance surface finish and tool life.

Aluminum is commonly used in aerospace, automotive, and consumer electronics due to its excellent strength-to-weight ratio and good corrosion resistance. Grades like 6061 and 7075 are popular choices, with each offering unique properties suited to different applications.

Local Brass Supply for Your CNC Machining Needs

If you’re looking at the advantages of CNC machining brass vs. aluminum for your next project, Industrial Metal Service is here to help.

For more than two decades, we’ve been providing metal recycling services to the San Francisco Bay Area as well as supplying local machine shops, fabricators, and metalworkers with metals like brass and aluminum.

We also ship to customers across the U.S. who don’t have the benefit of a local supplier—with no minimum order quantities.

We stock an extensive inventory of custom brass parts and alloys and offer customers the option of buying new metal sourced from U.S. mills or verified remnants, which offer considerable savings.