Brass vs Aluminum: CNC Machining Materials Comparison Guide

When choosing materials for CNC machining, two of the most commonly considered metals are brass and aluminum. But how do you know which one is the best for your project? Whether it’s strength, corrosion resistance, machinability, or aesthetic appeal, this comprehensive guide will help you compare brass and aluminum based on key factors that affect the performance and costs of CNC machined parts.

In the realm of CNC machining, brass stands out due to its superior strength and corrosion resistance, making it ideal for applications requiring resilience to mechanical stress and corrosive conditions. On the other hand, aluminum, noted for its lightweight yet high strength, coupled with its excellent cutting properties, good thermal conductivity, and cost-efficiency, has emerged as the preferred material for those seeking lightweight designs, efficient processing, and economic benefits.

Let’s take a closer look at the unique characteristics of brass and aluminum, and understand how their properties affect machining processes and end-use applications.

What is CNC Machining?

CNC machining refers to the process of using computer-controlled machines to cut and shape materials into specific forms. CNC machines offer high precision and repeatability, making them ideal for producing intricate parts. Whether you’re working with brass or aluminum, CNC machines ensure that every part meets the required tolerances with minimal material waste. Both materials are highly popular in CNC machining due to their diverse applications across industries.

Overview of Brass

Brass is a copper-based alloy primarily composed of copper and zinc, though other elements like lead and tin can also be included. Known for its durability, strength, and excellent corrosion resistance, brass is used in a wide range of applications that require wear resistance, such as fittings, valves, and decorative parts. The two most common brass grades used in CNC machining are Brass 360 and Brass 260.

Brass 360 is popular for its excellent machinability and is used in industries requiring precise parts, such as electronics and plumbing. It provides a golden hue that also makes it ideal for ornamental applications. On the other hand, Brass 260 offers greater strength and durability, suitable for parts that need to withstand high stress or harsh environments.

Overview of Aluminum

Aluminum is one of the most widely used metals in CNC machining due to its versatility and exceptional strength-to-weight ratio. It is highly machinable, making it easier to cut, shape, and finish than many other metals. Aluminum alloys are available in a variety of grades, each designed for different applications. 6061 Aluminum is one of the most commonly used grades, known for its balance of strength, corrosion resistance, and machinability.

In addition, 7075 Aluminum is another popular alloy used in aerospace and military applications due to its superior strength, though it is more difficult to machine compared to other aluminum grades. Aluminum is lightweight, which makes it perfect for industries where weight reduction is critical, such as aerospace, automotive, and consumer electronics.

Note: If you want to know more about aluminum, you can read the following articles:

CNC Machining Methods, Materials, And Advantages Of Aluminum Parts

How Much Does It Cost to CNC Machining Aluminum Parts?

Advantages and Applications of CNC Aluminum Housings

Brass and Aluminum Grades for CNC Machining

Both brass and aluminum are available in various grades, each specifically designed for certain CNC machining applications. Understanding the differences in material properties and selecting the right alloy ensures the best performance, durability, and machinability for your parts.

Brass Grades for CNC Machining

Brass alloys are prized for their machinability, corrosion resistance, and aesthetic appeal. These characteristics make brass ideal for intricate parts and decorative components. Here are the most commonly used brass grades in CNC machining:

Brass 360

Brass 360, often referred to as free-cutting brass, is the most widely used brass alloy in CNC machining due to its superior machinability. This alloy contains around 63% copper and 37% zinc, along with a small amount of lead, which enhances its machinability. The lead content makes it easier to machine, enabling high-speed cutting and smoother finishes, which reduces tool wear and increases productivity.

It is primarily used to manufacture small precision components such as connectors, fittings, electrical contacts, and musical instruments. The excellent surface finish and ease of machining make it ideal for producing detailed, intricate parts with minimal defects.

However, Brass 360 is not as strong as some other alloys, so it is not suitable for high-stress applications where extreme mechanical strength is needed.

Brass 260

Brass 260 is a high-strength brass alloy containing approximately 70% copper and 30% zinc, without lead. It offers a higher tensile strength compared to Brass 360, making it suitable for parts that require greater durability and wear resistance. While it is slightly harder to machine than Brass 360, it still offers relatively good machinability and is often used for more robust applications.

This grade is ideal for producing components like bushings, gears, machine components, and high-stress fasteners. These applications demand materials that can withstand mechanical loads and repetitive use. Brass 260 is also a popular choice in automotive and aerospace industries where durability is crucial.

Brass 270

Brass 270, or Muntz Metal, is composed of 60% copper and 40% zinc. This alloy is valued for its excellent corrosion resistance and good strength, especially in marine environments. It is commonly used in applications where parts will be exposed to harsh outdoor or seawater conditions.

Although its machinability is slightly lower than Brass 360, Brass 270 still offers excellent durability for producing marine hardware, plumbing fittings, and electrical components. It’s an excellent choice for applications where corrosion resistance is a priority, particularly in saltwater environments.

However, due to its high zinc content, Brass 270 can be susceptible to dezincification in very corrosive conditions, which may affect the material’s strength over time.

Aluminum Grades for CNC Machining

Aluminum alloys are favored for their lightweight, corrosion-resistant properties, and versatility in various CNC machining applications. Aluminum alloys are often used in industries ranging from automotive to aerospace due to their strength-to-weight ratio. Below are some of the most common aluminum grades used in CNC machining:

6061 Aluminum

6061 Aluminum is one of the most versatile and widely used aluminum alloys in CNC machining. It contains aluminum, magnesium, and silicon, making it highly resistant to corrosion and providing a good balance of strength, machinability, and weldability. This alloy is often referred to as the “workhorse” of the aluminum industry due to its adaptability in a wide range of applications.

6061 aluminum is commonly used in the automotive, marine, aerospace, and construction industries. Applications include structural components, frames, vehicle parts, and electronic housings. The alloy’s good strength-to-weight ratio and excellent corrosion resistance make it ideal for both outdoor and structural applications where strength and durability are required without the added weight of other metals.

While it is easy to machine and form, 6061 aluminum is not as strong as other high-performance alloys like 7075 and may not be suitable for applications requiring maximum strength or load-bearing capacity.

7075 Aluminum

7075 Aluminum is known for its exceptional strength and is one of the strongest aluminum alloys available. It is composed of aluminum, zinc, and magnesium, with trace amounts of copper and chromium. This alloy is specifically designed for high-performance applications, making it a top choice in the aerospace and military industries.

Due to its high strength, 7075 aluminum is used for aircraft components, military equipment, and high-performance sports gear. Although it is incredibly strong, it is more challenging to machine compared to alloys like 6061 aluminum due to its increased hardness. Proper tooling and machining techniques are required to prevent overheating, tool wear, and material distortion.

2024 Aluminum

2024 Aluminum is another high-strength alloy, typically used in aerospace and aviation applications. It contains significant amounts of copper, which contributes to its high strength, but also makes it more prone to corrosion. Therefore, 2024 aluminum is typically used in applications where strength is the primary concern, and the component can be protected from corrosive environments.

This alloy is commonly used for aircraft structures, aircraft wings, fuselages, and engine components. While it has excellent fatigue resistance, its susceptibility to corrosion means it may need additional coatings or surface treatments like anodizing to extend its life in corrosive environments.

5083 Aluminum

5083 Aluminum is a marine-grade aluminum known for its exceptional corrosion resistance, especially in saltwater and harsh environments. It contains a high amount of magnesium, making it particularly suitable for parts exposed to seawater.

This alloy is used extensively in marine applications such as ship hulls, offshore oil rigs, marine vessels, and pressure vessels. Its excellent corrosion resistance makes it ideal for use in marine hardware and chemical tanks. However, 5083 aluminum is not as strong as 7075 aluminum and may not be suitable for high-stress applications requiring maximum strength.

Properties of Brass and Aluminum

When comparing brass and aluminum, understanding their material properties is crucial for selecting the appropriate alloy for a given CNC machining application. The following table outlines the key properties of these two metals, highlighting their differences in terms of density, hardness, tensile strength, corrosion resistance, machinability, and weight. By examining these properties, you can make a more informed decision on which material.

Property	Brass	Aluminum
Density	Higher (8.5 g/cm³)	Lower (2.7 g/cm³)
Hardness	Higher hardness (200 HV)	Lower hardness (70 HV)
Tensile Strength	Higher strength (up to 500 MPa)	Lower strength (around 250 MPa)
Corrosion Resistance	Excellent resistance	Good, but less than brass
Machinability	Good, but harder to machine	Excellent machinability
Weight	Heavier, not ideal for lightweight parts	Lightweight, ideal for weight-sensitive applications

Comparison of Brass and Aluminum

Is Brass Harder than Aluminum?

Brass is harder than aluminum, with a hardness rating of around 200 HV, making it more resistant to wear and mechanical stress. This makes brass ideal for high-stress applications like bushings and fittings. In contrast, aluminum has a lower hardness (about 70 HV) and is more prone to wear, but its lightweight nature makes it suitable for applications where weight is a critical factor.

Brass vs Aluminum Strength

Brass is generally stronger than aluminum, with a tensile strength that can reach up to 500 MPa compared to aluminum’s typical 250 MPa. This makes brass more suitable for applications where strength is crucial, such as in high-stress machine components, bushings, and valves that need to withstand pressure and frequent wear.

However, aluminum offers a superior strength-to-weight ratio, making it the preferred material for industries that prioritize reducing weight without compromising too much on strength. Aluminum is widely used in aerospace, automotive, and other weight-sensitive applications, where the need for a lightweight yet durable material is essential.

Is Brass Easier to Machine than Aluminum?

In general, aluminum is easier to machine than brass. This is due to its lower hardness and lighter weight, which make it simpler to cut, drill, and mill with less wear on tools. Aluminum’s softer nature allows for quicker and more efficient machining, especially in high-volume production settings where speed is essential. Additionally, aluminum produces less heat during machining, helping to prolong tool life and reduce machining costs.

On the other hand, brass is harder and more challenging to machine compared to aluminum. The increased hardness can lead to faster tool wear and demands more advanced machining techniques to achieve the desired precision. While brass still offers good machinability when compared to harder metals like steel, machinists may need to adjust parameters such as feed rate, speed, and lubrication to ensure optimal results.

Brass vs Aluminum Corrosion Resistance

Brass offers superior corrosion resistance compared to aluminum, especially in environments where exposure to saltwater or moisture is common. Brass is highly resistant to corrosion caused by saltwater, making it an excellent choice for marine environments, plumbing fittings, and other applications exposed to harsh conditions. Its corrosion-resistant properties stem from the zinc and copper alloys, which form a protective layer on the material’s surface.

While aluminum also has natural corrosion resistance due to its oxide layer, it is more vulnerable to oxidation in certain environments. In cases where aluminum is exposed to extreme moisture or harsh chemicals, the oxide layer can break down, leading to corrosion. To prevent this, aluminum is often anodized, coated, or treated with protective finishes to enhance its resistance and prolong its lifespan in challenging environments.

Brass vs Aluminum Price

Aluminum is generally less expensive than brass, making it a more cost-effective option for many industries. The relatively abundant supply of raw aluminum and the simpler manufacturing and processing methods contribute to its lower price. As a result, aluminum is often the material of choice for large-scale production and applications where cost savings are a priority.

On the other hand, brass is more expensive due to its higher copper content and more complex alloying process. Brass requires more specialized manufacturing processes, which can add to its cost. While brass is typically chosen for its higher strength, durability, and aesthetic appeal, the material’s premium price may limit its use to more specialized applications or products where these qualities justify the higher cost.

Surface Finish and Aesthetics

When it comes to aesthetics, brass has a natural golden color that is highly desirable for decorative applications. Its inherent shine and unique appearance make it a popular choice for jewelry, hardware, and decorative architectural elements. Additionally, brass can be polished to a high shine or patinaed to create a vintage or antique look, allowing it to complement a range of design styles.

Aluminum, while not naturally golden like brass, offers versatility in surface finishing. Aluminum can be anodized to create a durable, corrosion-resistant surface that is available in various colors. It can also be treated with dyes, coatings, or polished to achieve a range of finishes, from matte to high-gloss reflective surfaces. This flexibility makes aluminum an ideal material for a wide array of applications, from consumer electronics to automotive parts.

What Metal is the Easiest to Machine?

Of the two, aluminum is easier to machine. Its lower density, softness, and high thermal conductivity make it ideal for high-speed machining and rapid material removal. This makes aluminum especially popular in mass production and industries where cost efficiency and quick turnarounds are important. In contrast, brass requires slower machining speeds and specialized tooling to maintain efficiency.

How Hard is Brass to Machine?

While brass is relatively easy to machine compared to steel, it is harder than aluminum. The machinability of brass depends on the specific alloy, with Brass 360 being easier to machine than Brass 260, for instance. Due to its hardness, brass requires more advanced tooling, such as carbide cutting tools, to achieve clean, precise cuts without excessive tool wear.

Core Skills in Aluminum and Brass CNC Machining

To successfully machine both brass and aluminum, machinists must understand the material properties and adapt their approach accordingly. For aluminum, machinists must be mindful of the material’s softer nature and lower hardness, which allows for faster cutting speeds but also requires attention to tool wear and potential heat buildup.

For brass, the challenge lies in its higher hardness, which can cause more tool wear. Achieving smooth and precise cuts requires appropriate lubrication and cooling, especially during longer machining cycles. Lubricants prevent the buildup of brass material on cutting tools, which is critical for maintaining precision and extending tool life. Understanding both the mechanical and thermal properties of these materials is key for successful CNC machining.

Machining Brass Alloys

Machining brass alloys requires attention to both the physical properties of the alloy and the machining conditions. For Brass 360, which is renowned for its excellent machinability, high-speed cutting tools are commonly used to maximize productivity. The low friction of Brass 360 makes it relatively easy to machine at higher speeds without generating excessive heat. Additionally, Brass 360 parts benefit from minimal tool pressure, ensuring smooth surface finishes and high dimensional accuracy. However, Brass 260 presents more challenges due to its higher tensile strength and lower machinability, requiring slower cutting speeds to manage heat buildup and prevent surface discoloration.

Specialized cutting fluids are often necessary for machining brass alloys, particularly in maintaining temperature control during the process. These fluids help flush away debris and cool the cutting area, allowing for longer tool life and improved surface quality. Additionally, controlling the temperature during machining is essential to prevent material deformation and to ensure smooth cuts, especially when working with tougher brass grades. Properly choosing the machining setup based on the specific brass alloy can significantly impact production efficiency and part quality.

Machining Aluminum

Aluminum machining is generally faster and less complicated than machining brass, mainly due to aluminum’s lower hardness and better thermal conductivity. Common aluminum alloys, like 6061 and 7075, can be machined at high speeds with carbide tools, making it easier to produce large quantities of parts in a short amount of time. Aluminum’s ability to conduct heat more efficiently also helps reduce the risk of overheating during the machining process, allowing for cleaner cuts with fewer defects. Machinists often focus on low cutting forces to avoid warping the part and producing a high-quality finish.

While aluminum machining may require less coolant than brass, coolant still plays an important role in cooling and reducing friction between the tool and material. In some cases, especially with 6061 aluminum, minimal coolant or air blasting is used, as excessive cooling can lead to poor surface finishes or distortions. For harder aluminum grades like 7075, special care is needed to control the feed rates and cutting speeds, as the increased hardness of the material requires slower machining to ensure precision. Proper tool selection, as well as effective management of cutting parameters, is critical to achieving the best possible results in aluminum CNC machining.

Brass and Aluminum Specific Applications

Brass Specific Applications

Brass is a highly versatile material with several unique properties, including high strength, excellent corrosion resistance, and good machinability, making it suitable for a wide range of applications, especially in industries that demand durability and aesthetic appeal.

Automotive Industry

Brass is often used in the automotive industry for various components such as fittings, valves, brake systems, and carburetors. Brass’s resistance to corrosion makes it ideal for parts that come into contact with liquids and gases. The material’s ability to withstand extreme conditions without degrading ensures long-lasting performance in automotive applications.

Plumbing Fittings

Brass is a popular choice for plumbing fittings due to its excellent corrosion resistance to water and other fluids. It is commonly used for pipe fittings, valves, hose bibs, and faucets. Brass’s ability to withstand pressure and its anti-corrosive properties in water systems make it an ideal material for long-lasting plumbing components.

Electrical Components

Brass is also used in the electronics and electrical industry for components such as connectors, switches, terminals, and relays. Brass’s conductivity, combined with its resistance to oxidation and corrosion, makes it ideal for use in electrical circuits and connections, especially for low-voltage applications.

Precision Machining Parts

Brass is often selected for precision CNC machining parts due to its excellent machinability. Parts like gears, bearing housings, and fasteners benefit from brass’s ease of cutting and forming, as well as its strength and longevity.

Aluminum Specific Applications

Aluminum is a lightweight and highly versatile material that is widely used across various industries due to its low density, high strength-to-weight ratio, and excellent corrosion resistance. It’s often preferred for applications that require lightweight yet durable materials.

Aerospace Industry

In the aerospace sector, aluminum is critical for creating aircraft frames, wings, engine components, and landing gears. Its lightweight nature helps reduce the overall weight of aircraft, improving fuel efficiency and performance. Additionally, aluminum’s high strength-to-weight ratio makes it ideal for parts that need to withstand extreme stresses while maintaining low weight.

Automotive Industry

Aluminum is increasingly used in the automotive industry for parts such as engine blocks, transmission housings, wheels, and body panels. The lightweight properties of aluminum are crucial in automotive design, as they help improve fuel efficiency, reduce carbon emissions, and enhance overall vehicle performance.

Electronics Industry

Aluminum is widely used for electronic housings, such as laptop casings, smartphone enclosures, and heat sinks for computers and power electronics. The material’s excellent thermal conductivity helps dissipate heat effectively, making it ideal for cooling high-performance electronic components. Additionally, aluminum is valued for its aesthetic appeal in consumer electronics.

Heat Exchangers

Aluminum is an ideal material for heat exchangers due to its ability to conduct heat efficiently. In applications like air conditioning systems, radiators, and industrial cooling systems, aluminum’s thermal conductivity makes it a critical component for transferring heat away from hot systems to cooler environments.

Construction and Architectural Applications

Aluminum is widely used in construction, especially for window frames, curtain walls, roofing, and doors. The material’s corrosion resistance makes it suitable for exterior applications, ensuring long-term durability in outdoor environments. Aluminum’s lightweight nature reduces structural load, while its aesthetic versatility offers a range of design possibilities for modern architectural designs.

Precision Components in CNC Machining

CNC machining of aluminum parts is a staple in industries such as medical, electronics, and industrial machinery. Aluminum’s workability makes it easy to create precise, intricate parts such as valves, casing components, robotic parts, and small fixtures that require tight tolerances and excellent surface finishes.

Brass and Aluminum Compatibility

While brass and aluminum have distinct advantages, their compatibility in certain applications can sometimes be a concern due to the potential for galvanic corrosion when they are in contact in corrosive environments. For example, when both materials are exposed to moisture, brass and aluminum can react and corrode more quickly than if they were isolated from each other.

In Conclusion

In CNC machining, both brass and aluminum have unique advantages depending on the specific application. Brass offers superior strength and corrosion resistance, making it ideal for high-stress, decorative, or marine applications. Aluminum, on the other hand, is easier to machine and more lightweight, making it an excellent choice for applications where weight reduction and cost-effectiveness are key considerations. Understanding the properties and applications of both metals will guide you toward making the best material selection for your project.

Start Your CNC Machining Project at VMT

At VMT, we are not only good at utilizing the excellent properties of brass and aluminum, but also combine advanced sheet metal manufacturing technology, 3D printing technology and CNC machining technology to accurately process a variety of materials including brass and aluminum. These technologies not only improve our production efficiency and processing accuracy, but also enable us to provide highly customized parts solutions based on the unique needs of our customers. Whether it is complex geometry or fine tolerance control, we can achieve them one by one, ensuring that customers from all walks of life achieve the best reliability and performance in their products.