Bronze, a very adaptable material, is widely used in many applications. Bronze, an alloy of copper, tin, and other elements, is prized for its excellent strength, durability, and corrosion resistance. These distinguishing characteristics make bronze a superb material for various CNC machining applications, including bearings, gears, and precision components.

Bronze is also machinable, allowing it to be precisely molded, drilled, and machined using CNC machines. As a result, it has become a popular choice for high-precision component industries such as aerospace, automotive, and medical device manufacturing. This guide explains all you need to know about Bronze CNC machining.

What Is Bronze CNC Machining?

Bronze is created by combining copper with up to 35% tin and 8% lead. The presence of lead alloy, a soft metal, is what makes it so machinable. Bronze is ideal for bearings and maritime applications such as pumps and fittings that require corrosion resistance against seawater. Because the mechanical properties of this material differ from those of many other machinable metals, it is best employed on low-stress components manufactured using CNC machining.

Bronze, brass, and other copper alloys have several electrical, mechanical, and corrosion-resistant qualities. Bronze, in particular, has a great machinability rating of 100%. It also has low friction qualities, making it excellent for CNC machining bronze parts that are constantly in contact with one another. 

Furthermore, bronze’s mechanical qualities and performance attributes can be enhanced through various compositions and treatments. For example, the addition of phosphorous can increase its resistance to wear, but the addition of aluminum can increase its strength and hardness. 

Bronze CNC Machining Process

Milling head cutting on bronze material
Milling head cutting on bronze material

The bronze CNC machining process involves utilizing computer numerical control (CNC) machines to shape and refine bronze material with precision. Recognized for its robustness, resistance to corrosion, and aesthetic appeal, bronze is a favored choice for diverse applications.

Initiating with creating a comprehensive CAD (Computer-Aided Design) model, the process relies on CAM (Computer-Aided Manufacturing) software to generate toolpaths, guiding the CNC machine in crafting the bronze component. Following this, the chosen bronze material is prepared and secured onto the CNC machine’s work table.

Subsequently, the CNC machine is set up by loading the CAD file and corresponding toolpath program, along with carefully calibrating essential tools. Machining operations encompass bronze CNC milling, bronze CNC turning (for rotational symmetry), drilling, 5-axis CNC machining, and finer details like engraving or etching.

Post-machining, the bronze piece undergoes meticulous inspection to verify adherence to specified tolerances and quality standards, employing precision measuring instruments. Depending on the intended application, additional finishing steps such as polishing or sanding may be implemented to achieve the desired texture and appearance.

A final inspection ensures all requirements are met, after which the finished bronze component is meticulously packaged for transportation or subsequent assembly. It is crucial to note that the intricacy of the component and the capabilities of the CNC machine can influence the specific steps involved. Additionally, the expertise of skilled CNC operators is pivotal in attaining top-notch results.

Advantages of Bronze CNC machining 

Hole center drill process on bronze material
Hole center drill process on bronze material

Bronze has various advantages that make it perfect for CNC machining, including superior lubricity. This advantage improves production efficiency and savings over denser metals that require continuous lubrication during cutting. Bronze is also more sturdy and long-lasting than many other materials, making it an excellent choice for items that require a longer service life.

Here are some other advantages of bronze CNC machining

  • Superior Machinability: Bronze’s composition lends itself to easy and precise machining, allowing for the creation of intricate and complex shapes with minimal tool wear.
  • Excellent Corrosion Resistance: Bronze’s resistance to corrosion makes it a good choice for components exposed to harsh environmental conditions or corrosive substances.
  • Satisfactory Strength and Hardness: While not as hard as some metals, bronze balances strength and malleability, making it versatile for various applications.
  • Exceptional Thermal Conductivity: Bronze’s high thermal conductivity facilitates efficient heat dissipation during machining, reducing the risk of overheating and ensuring dimensional accuracy.
  • Low Friction Properties: Bronze’s low friction coefficient is advantageous in applications where reduced friction and wear are crucial, such as bearings and sliding components.

Disadvantages of Bronze CNC machining 

Despite its notable advantages, bronze CNC machining does come with certain drawbacks that warrant consideration:

Higher Material Costs

Bronze, being a composite of copper and tin, tends to be pricier compared to alternative materials. This can lead to increased overall expenses for projects involving bronze CNC machining.

Tool Wear and Replacement

Due to its softer nature, bronze can cause accelerated wear and tear on machining tools. This may necessitate more frequent tool replacements, adding to production costs.

Complex Geometry Challenges

Achieving intricate features and complex geometries can be more challenging with bronze than harder metals. The material’s softer composition may limit its ability to retain fine details effectively.

Extended Machining Times

Machining operations on bronze may take longer due to its softer composition. This extended machining time can lead to prolonged production durations.

Increased Heat Generation

Bronze machining tends to generate more heat compared to the machining of harder metals. This excess heat can impact tool longevity and performance, requiring vigilant monitoring and potentially slowing down the process.

What Are the Bronze Types Available for CNC Machining?

CNC turning on a bronze
CNC turning on a bronze

Here are some of the bronze types available for CNCbronze machining:

Copper 932

Copper 932 is also known as SAE 660. It is a bearing bronze alloy with a high concentration of copper, tin, and zinc. It is widely used in producing bushings, bearings, and other precision components requiring high strength, wear resistance, and outstanding anti-friction qualities.

Because of its natural propensity to generate a lubricating coating on its surface, copper 932 is a pchoice for applications where lubrication is problematic. This decreases the possibility of friction and wear, extending the component’s lifespan and improving overall performance.

Copper 932 is very easy to mold, drill, and mill to precise specifications using CNC equipment. As a result, it is a preferred choice for industries requiring high-precision components, such as aerospace, automotive, and industrial manufacturing. Overall, Copper 932 is a dependable and adaptable erfectmaterial for CNC machining applications, and its high strength, wear resistance, and anti-friction qualities make it an excellent choice for demanding applications requiring performance and endurance.

 PB1Grade

The PB1 grade bronze meets the BS1400 standard. Because of its outstanding fatigue resistance, this grade of bronze is also known as ‘Phosphor bronze’ due to the inclusion of phosphor used in manufacture to improve its wear resistance and stiffness. It is commonly used for bearings, particularly for heavy loads at high speeds. PB1 is also ideal for producing worm gears, springs, valve bodies, gears, and bushes due to its outstanding formability, superior spring characteristics, and solderability.

PB1, also known as phosphor bronze, has a very high tin concentration, which improves its strength and corrosion resistance, particularly in seawater and chloride environments, making it an excellent choice for usage in the aerospace, marine, and chemical sectors.

Silicon Bronze

Silicon bronze, often red silicon bronze, comprises copper, silicon, and zinc. It includes up to 6% silicon on average. It can also contain copper, silicon, and other alloys like manganese, tin, iron, and zinc. It is a high-strength alloy with good pouring ability, corrosion resistance, and an excellent surface polish. Pump and valve parts are the most prevalent applications.

Aluminum Bronze

Aluminum bronze
Aluminum bronze

Aluminum bronze comprises copper, 6 to 12% aluminum, and occasionally additional elements such as iron, nickel, manganese, and silicon. It is a high-strength alloy that is also corrosion- and tarnish-resistant. Because of its resistance to corrosion, particularly in seawater, frequent applications include naval hardware and pumps that transport corrosive fluids. It is also utilized in the oil and petrochemical industries, as well as in water supply.

Phosphor Bronze

Phosphor bronze, commonly known as tin bronze, is composed of copper, up to 11% tin, and 0.35% phosphorus. The inclusion of phosphorus improves the wear resistance and rigidity of the metal. This alloy is noted for its toughness and durability, as well as its low coefficient of friction and fine grain. Phosphor bronze is widely utilized in the production of anti-corrosive equipment, electrical components, washers, bronze CNC prototyping parts, springs, bellows, and musical instruments.

Bearing Bronze

Bearing bronze contains between 6 and 8% lead. Because of the higher lead content, it has a low friction feature, making it beneficial in high-wear applications, particularly in difficult-to-access or maintain places. Bearing bronze is most commonly used to create bearings and bushings, as the name implies.

Bismuth Bronze

Bismuth bronze contains between 1% and 6% bismuth. It is more flexible and thermally conductive, as well as very corrosion resistant. It polishes well and is hence occasionally used in light reflectors and mirrors. Bearings are the most prevalent industrial use. However, it has historically been used as cookware. Bismuth bronze was also discovered in ceremonial Inca knives found at Machu Picchu. It is now utilized as an alternative to leaded bronze in some cases.

Manganese Bronze

Manganese bronze contains up to 3% manganese and copper, zinc, aluminum, and iron. It is resistant to shock and deforms rather than shattering. Because it is particularly resistant to saltwater corrosion, it is frequently used in boat propellers. Manganese bronze is also utilized in valve and pump components, gears, nuts, rapid prototyping, and bolts.

Copper-Nickel

Copper-nickel bronze, commonly known as cupronickel, has more nickel, ranging from 2 to 30%. It is sturdy and corrosive-resistant, especially against saltwater, like other bronze alloys. It is also very thermally stable. Electronic components, marine equipment, ship hulls, pumps, and valves are all copper-nickel bronze.

Surface Finishes for Bronze CNC Machining

Due to its outstanding mechanical qualities, machinability, and corrosion resistance, bronze is a preferred material for a wide range of CNC machining applications. Bronze can be polished in several ways to improve its performance and looks. As-machined, bead blasting and chemical coatings are the three most common surface treatments for bronze. Here, we will address the benefits and drawbacks of each of these finishes:

As-machined Surface Finish

The natural finish of the bronze material following CNC machining is the as-machined surface finish. This finish is often smooth and homogeneous, with a matte look. The key benefit of this finish is that it is inexpensive and does not require any additional processes or materials. However, the surface may have minor tool marks or burrs that compromise the component’s aesthetics and functionality. To create a smoother surface finish, extra post-machining techniques may be required.

Bead blasting 

This is a finishing technique that involves launching delicate beads or particles onto the surface of the bronze substance. This procedure produces a homogeneous matte finish that is smooth and can improve the component’s appearance. By eliminating any surface particles or impurities, bead blasting can increase the corrosion resistance of the metal. However, this process can be time-consuming and costly, and it can also result in microscopic pits or roughness on the material’s surface, which may impact the component’s operation.

Chemical Coatings

This is a surface finish in which a small layer of chemicals is applied to the surface of the bronze substance. This procedure can improve the component’s appearance, longevity, and functionality. Chemical coatings can give the bronze material good corrosion resistance, wear resistance, and anti-friction qualities. Furthermore, by adding bronze color or shine to the surface, this finish can improve the appearance of the component. However, this technique is costly and necessitates specialized equipment and experience. Furthermore, due to the possibility of chemical reactions or toxicity, the chemical coating may not be acceptable for some purposes.

Cost-saving Design Tips for Bronze CNC Machining

Operation of lathe machine cutting the bronze shaft material
Operation of lathe machine cutting the bronze shaft material

Here are some of the cost-saving design tips for bronze CNC machining:

Consider Post-machining Processes

To attain surface smoothness or performance attributes,customized cnc machining bronze parts may require extra post-machining procedures. To avoid additional expenses or manufacturing delays, it is critical to design your parts with these processes in mind.

Optimize Wall Thickness

Bronze parts that are too thin may distort or warp during the CNC machining process, whereas parts that are too thick may be challenging to produce and result in unnecessary material waste. As a result, optimizing the wall thickness of your bronze pieces is critical to ensuring that they are both structurally robust and readily manufacturable.

Consider Material Properties

Bronze is a versatile material that may be customized with various compositions and treatments to improve mechanical attributes and performance. As a result, it is critical to analyze your application’s needs and select the right bronze type and treatment to optimize the performance and longevity of your parts.

Minimize Undercuts

Undercuts are parts that are difficult or impossible to manufacture with normal cutting tools. Because these areas can increase the complexity and cost of CNC machining, it is best to minimize undercuts or design them to be easily machined.

Avoid Sharp Corners and Edges

Because bronze is a soft material, sharp corners or edges can produce stress concentrations, leading to cracking or other structural failures. As a result, whenever practical, employ rounded corners or fillets to distribute stress more evenly and increase the overall strength of the component.

Applications of Bronze Machined Parts

Manufacturers in agriculture, automotive, and heavy vehicles use bronze for its resilience and extended life. Typical bronze CNC machined items include:

  • Threaded components
  • Taps
  • Nuts and bolts
  • Gears and bearings
  • Electrical terminals
  • Screws
  • Bushings.

Conclusion

Bronze is a great CNC machining material. Its toughness makes it easy to work with and enables exact cuts that are difficult to obtain with other metals. This metal is solid and durable, but its malleability makes it suitable for complicated shapes and tight tolerances. 

Consider using bronze in your next project if you’re seeking a dependable material that can withstand wear and tear while producing stunning results every time! Contact Zintilon for all your bronze CNC machining services. 

FAQs

Is Bronze Easy to Machine?

Yes, bronze is easy to machine. CNC machinery such as lathes, mills, and routers can machine it. Bronze is a soft and malleable material that is easy to manufacture and mold into precision components. Bronze’s machinability can be improved using the proper cutting tools, feeds, and speeds.

Is Bronze More Machinable than Brass?

Because of its higher flexibility and lower zinc concentration, bronze is regarded as more machinable than CNC machining brass. Bronze is often made up of copper and tin, whereas brass comprises copper and zinc. Brass’s zinc concentration can make it brittle and difficult to manufacture, especially in high-speed machining operations.

What Are the Top Grades of Bronze for CNC Machining?

The optimum bronze grades for CNC machining are those with a greater copper content.

C954 aluminum bronze, C630 nickel aluminum bronze, and C863 leaded tin bronze are the most popular bronze grades used for CNC machining. All three of these grades have good machinability and corrosion resistance.

Because it has the highest strength of any bronze choice for CNC machining and is reasonably easy to manufacture, C954 machining aluminum bronze is the most preferred grade.

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