A Guide to CNC Machining with Bronze: Properties, Advantages, and Tips


About Bronze

Bronze, a remarkably versatile material, finds extensive utilization across diverse applications. Comprising an alloy of copper, tin, and occasionally other elements, bronze is esteemed for its exceptional strength, durability, and resistance to corrosion. These distinctive qualities render bronze an ideal material for an extensive array of CNC machining applications, encompassing bearings, gears, and precision components.

The machinability of bronze is also commendable, allowing it to be easily shaped, drilled, and milled with precision using CNC machines. Consequently, it has become a favored option for industries necessitating high-precision components, including aerospace, automotive, and medical device manufacturing.

Moreover, bronze can be tailored through varied compositions and treatments to augment its mechanical properties and performance characteristics. For instance, the introduction of phosphorus can heighten its resistance to wear, while the addition of aluminum can enhance its strength and toughness.


Copper 932

Copper 932, also known as SAE 660, is a type of bearing bronze alloy that contains high levels of copper, tin, and zinc. It is a popular material for the manufacture of bushings, bearings, and other precision components that require high strength, wear resistance, and excellent anti-friction properties.

Copper 932 is an excellent choice for applications where lubrication is difficult, as it has a natural ability to form a lubricating film on its surface. This reduces the risk of friction and wear, which can extend the lifespan of the component and improve overall performance.

Additionally, Copper 932 has good machinability, which means it can be easily shaped, drilled, and milled to precise specifications using CNC machines. This makes it a popular choice for industries that require high-precision components, such as aerospace, automotive, and industrial manufacturing.

Overall, Copper 932 is a reliable and versatile material for CNC machining applications, and its high strength, wear resistance, and anti-friction properties make it an ideal choice for demanding applications where performance and durability are critical.

Surface Finishes

Bronze is a popular material for a wide range of CNC machining applications due to its excellent mechanical properties, machinability, and corrosion resistance. To further enhance its performance and aesthetics, bronze can be finished in a variety of ways. The three main types of surface finishes for bronze are as-machined, bead blasting, and chemical coatings. In this response, we will discuss the advantages and disadvantages of each of these finishes.

As-machined surface finish is the natural finish of the bronze material after CNC machining. This finish has a matte appearance and is typically smooth and uniform. The main advantage of this finish is that it is cost-effective and requires no additional processes or materials. However, the surface can have slight tool marks or burrs, which can affect the aesthetics and functionality of the component. Therefore, additional post-machining processes may be required to achieve a smoother surface finish.

Bead blasting is a finishing process that involves propelling fine beads or particles at the surface of the bronze material. This process creates a uniform matte finish that is smooth to the touch and can improve the appearance of the component. Bead blasting can also improve the corrosion resistance of the bronze by removing any surface contaminants or impurities. However, this process can be time-consuming and expensive, and it can also create tiny pits or roughness on the surface of the material, which may affect the functionality of the component.

Chemical coatings are a type of surface finish that involves applying a thin layer of chemicals onto the surface of the bronze material. This process can enhance the aesthetics, durability, and functionality of the component. Chemical coatings can provide excellent corrosion resistance, wear resistance, and anti-friction properties to the bronze material. Additionally, this finish can improve the appearance of the component by adding color or gloss to the surface. However, this process can be expensive and requires specialized equipment and expertise. Additionally, the chemical coating may not be suitable for certain applications due to the potential for chemical reactions or toxicity.

Overall, each of the three types of surface finishes for bronze has its own advantages and disadvantages. The selection of the appropriate surface finish depends on the specific requirements of the application, such as functionality, aesthetics, durability, and cost-effectiveness.

Design Tips

  1. Avoid sharp corners and edges: Bronze is a relatively soft material, and sharp corners or edges can cause stress concentrations that may lead to cracking or other structural failures. Therefore, it is advisable to use rounded corners or fillets wherever possible to distribute stress more evenly and improve the overall strength of the component.
  2. Optimize wall thickness: Bronze parts that are too thin can be prone to deformation or warping during the CNC machining process, while parts that are too thick can be difficult to machine and may result in excess material waste. Therefore, it is important to optimize the wall thickness of your bronze parts to ensure that they are both structurally sound and easily manufacturable.
  3. Consider post-machining processes: Bronze parts may require additional post-machining processes to achieve the desired surface finish or performance characteristics. Therefore, it is important to design your parts with these processes in mind to avoid additional costs or manufacturing delays.
  4. Minimize undercuts: Undercuts are areas of a part that are difficult to machine or impossible to access with standard cutting tools. These areas can increase the complexity and cost of CNC machining, so it is advisable to minimize undercuts or design them in a way that can be easily machined.
  5. Consider material properties: Bronze is a versatile material that can be customized with different compositions and treatments to enhance its mechanical properties and performance characteristics. Therefore, it is important to consider the specific requirements of your application and choose the appropriate bronze material and treatment to optimize the performance and durability of your parts.


Can bronze be machined?

Yes, bronze can be machined using CNC machines, such as lathes, mills, and routers. Bronze is a relatively soft and ductile material, which makes it easy to machine and shape into various precision components. The machinability of bronze can be further improved by using the appropriate cutting tools, feeds, and speeds.

Is bronze more machinable than brass?

In general, bronze is considered more machinable than brass due to its higher ductility and lower zinc content. Bronze is typically composed of copper and tin, while brass is composed of copper and zinc. The zinc content in brass can cause it to become brittle and difficult to machine, particularly in high-speed machining operations.

Can you EDM bronze?

Yes, bronze can be EDM (electrical discharge machined). EDM is a process that involves using an electric spark to erode material from a workpiece, creating a desired shape or feature. Bronze is a good material for EDM because it has good electrical conductivity and can be easily shaped and machined using this process.

Does bronze corrode easily?

Bronze has excellent corrosion resistance, particularly in environments that are high in moisture or salt content. This is because bronze naturally forms a protective oxide layer on its surface that prevents corrosion and oxidation. However, certain types of bronze may be more susceptible to corrosion in certain environments, such as those that contain acidic or alkaline substances. Therefore, it is important to choose the appropriate bronze material and surface finish for the specific application to ensure optimal corrosion resistance.

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