CNC Machining Bronze: How To Choose For Your Precision CNC Machining Parts | JS Precision

CNC machining bronze plays a very important role in the manufacturing of precision parts. Bronze, although an ancient alloy, has seen a resurgence with modern metal CNC machining technology. Mastery in this material, which embodies properties such as toughness and self-lubricating, needs experience that is highly specialized.

Apart from slowing down the projects, problems arising from improper material selection and process parameters greatly increase the cost of CNC machining bronze work.

The following guide is prepared to deal with these problems in CNC machining bronze, comprehensively teaching you how to do CNC machining bronze based on several years of practical experience from JS Precision. You can then avoid some pitfalls and produce qualified parts efficiently.

Core Answer Summary

Theme	Key Takeaways	Our Professional Solutions
Process Flow	From a 3D model to a finished product, it involves several precision stages of programming, machining, and quality inspection.	A fully digital workflow ensures traceability and controllability for every step.
Material and Tool	Bronze and brass vary in quite a few ways, so geometry and coating should be selected accordingly.	We have different tool libraries for various copper alloys and optimize the cutting parameters to get the best surface finish and tool life.
Challenges and Applications	The main challenges involve the viscosity of materials, heat management, and dimensional stability.Further, there is very high load-bearing in most applications in marine and automotive industries.	With long experience, we optimize the cutting fluid, parameters, and fixtures to fabricate high-precision and long-life bronze machined parts.
Service & Value	More than just machining, we offer services ranging from design optimization and material selection to surface treatment.	Furthermore, our CNC machining services are customized to drive value for you in the delivery of quality custom bronze parts that meet your expectations.

JS Practice: CNC Bronze Processing Material Selection And Pit Avoidance Guide

We have been deeply involved in CNC machining for 15 years. As a professional CNC machining company, we provide bronze CNC machining services for more than 800 customers in 12 industries: marine, heavy industry, art, and architecture.

We have successfully undertaken 18 mainstream bronze grades, such as phosphor bronze C54400, aluminum bronze C95400, and tin bronze C90300.

As an example, in 2024, we provided a heavy equipment company with 1000 pieces of phosphor bronze bearings, reaching 99.7% dimensional compliance with a shortened delivery cycle by 25% compared to the client expectation. We also did 50 complex bronze decorative pieces for an architectural studio, with detailed reproduction of the design.

This material selection guide for CNC bronze machining will help avoid several pitfalls.Our team tested every suggestion in real production for thousands of real project cases, helping one avoid very common mistakes in selection: "only looking at price without considering the performance" and "neglect of difference in machinability".

JS Precision will be able to help if you are struggling to find the right materials for a given CNC Machining Bronze project because we have much practical experience. It only takes providing design drawings and requirements to quickly find the corresponding solution and quote for customers, ensuring your project goes on well.

How Does The CNC Machining Bronze Process Work?

Understanding the key points on material selection and how to avoid pitfalls, you might be curious about the specific process of CNC machining bronze. The whole process includes five major steps, each of which directly influences the precision and quality of the parts.

Step 1: Digital Design (CAD) and Programming (CAM)

The engineers use design software to convert your design into a 3D model or 2D drawing, and further, with the use of CAM software, they write the machining program, converting it into G-code and M-code that the CNC machine tool will understand. Code errors will directly lead to machining errors, this is the foundation of CNC Machining.

Step 2: Material Preparation and Clamping

Choose the correct type of blank to be machined: for bearings, wear-resistant phosphor bronze, for marine parts, seawater-resistant aluminum bronze. Firmly fasten the blank to the machine tool by using a vise, chuck, and other clamps. Apply neither too large nor too small a force in order to avoid deformation or loosening of the blank.

Step 3: Precision Machining Execution

Based on the program, the machine tool performs turning, milling, drilling, tapping, and other operations. For instance, in the machining process of bronze bushings, the outer diameter, inner hole, and milling of the locating groove can be completed in one clamping to avoid clamping errors.

Step 4: Online Inspection and Quality Control

Probes measure dimensions in real time while machining. Every 10 parts machined, critical dimensions are checked. Deviations are promptly adjusted in the program or tooling, and this is the key to accuracy in CNC machining.

Step 5: Final Inspection and Deburring

Full-dimensional final checking includes confirmation to the requirements of the drawing, by quality inspectors, after machining with calipers and micrometers, in addition to a coordinate measuring machine. The sharp edges and burrs will be manually removed afterward to avoid scratching during assembly or in order to hold accuracy.

What Are The Key Factors In Successful Bronze Alloy Machining?

With CNC bronze machining mastered, successful bronze alloy machining depends on four factors that directly influence machining efficiency, part quality, and tool life.

Specific Material Grades

The machinability of different bronzes is huge: phosphor bronze - C54400 - is good for machinability, aluminum bronze - C95400 - is very hard and tough, its machinability has a tendency to wear the tools away, and sharp cutting edges and special parameters are needed. The following table presents the machinability of commonly used bronze grades:

Bronze Grade	Main Components	Machinability Grade (1-5, 5 is best)	Applicable Parts
C54400	Copper, Tin, Phosphorus	4.5	Bearings, Bushings
C95400	Copper, Aluminum, Iron	2.5	Marine Valves, Propellers
C90300	Copper, Tin	4	Marine Valves, Propellers

Cutting Speed ​​and Feed Rate

A too-low speed will result in low efficiency and rapid tool wear, while a too-high speed might cause heat generation that would cause deformation in the parts. To machine C54400 phosphor bronze, set the cutting speed to 150-200 m/min and the feed to 0.1-0.15 mm/r for an efficient balance of quality and productivity.

Cutting Fluid Selection and Application

Selection of cutting fluid is made according to the grade of bronze, and the extreme-pressure emulsion should be applied in machining aluminum bronze for removal of chips and lowering temperature. In machining phosphor bronze, the cutting fluid to be selected must be rust-preventive. The amount applied should be enough to cool the tool and parts.

Machine Tool Rigidity and Stability

The best levels of rigidity in machine tools are intrinsic to practically eliminating vibration, thus producing high accuracies. The bed of the JS Precision CNC machine tool is made from cast iron that ensures high rigidity, low vibration, and operational stability even when at high cutting speed. Poor rigidity in machine tools results in surface ripples and poor dimensional accuracy.

Parameter setting and equipment selection are both directly involved in bronze alloys machining. JS Precision provides you with high-rigidity CNC machine tools and an optimized cutting parameter library that may make a difference in efficiently machining qualified bronze machined parts. Please do not hesitate to contact us if you would like to discuss your project requirements.

Beyond Bronze: What Other Metals Can Be Handled By Metal CNC Machining?

Besides the CNC machining of bronze, metal CNC machining from JS Precision can handle many other metals, and has mature experience with various part requirements.

Extensive Material Capabilities

We can machine stainless steel (304, 316), aluminum alloys (6061, 7075), titanium alloys (TC4), tool steel (SKD11), etc.

In the machining of stainless steel, the parameters are adjusted to handle its high toughness, while in the machining of aluminum alloy, lightweight with good thermal conductivity provides great efficiency. It is basically a similar process to that used for CNC machining bronze, but adjustments have to be made in some key aspects based on characteristics.

Professional Material Selection

Our engineers give professional advice when the customer struggles to balance the cost, performance, and machinability of metals.

For lightweight and high-strength parts, 7075 aluminum alloy can be used, which is lighter than bronze by 40%, with a lower price, for parts that need to be resistant to corrosion, 316 stainless steel is recommended because it has better corrosion resistance than bronze in an acid or alkali environment.

CNC Machine Brass vs. Bronze: How To Choose The Right Cutting Tools?

In CNC machining, there is a difference in tools for CNC machine brass and bronze. Properly chosen cutting instruments can significantly enhance efficiency and quality. Let me explain this from three aspects:

Tool Geometry

Both are recommended to use sharp, positive rake angle fluted tools which reduce friction and allow clean shearing. In machining brass, the rake angle is set to 15°-20°, while for bronze, with its slightly higher toughness, the rake angle should be set to 12°-18° to prevent chip entanglement.

Tool material and coating

Both high-speed steel and ordinary cemented carbide are adequate for machining brass. For bronze alloy machining, diamond tools are recommended: life 5-10 times longer than ordinary cemented carbide, excellent surface quality. When the requirement for precision is relatively low, use cemented carbide tools coated with TiAlN to improve wear resistance.

Type of tool

Bronze machining tends to vibrate during turning, therefore, it requires a more rigid tool holder. During milling of bronze, four- or five-flute end mills are appropriate to increase stability. In drilling, increasing the drill bit tip angle will improve chip removal efficiency in machining bronze.

Different types of tools can be provided by JS Precision. They can perform well at CNC machine brass and CNC machining bronze. We can help you to select the most ideal one according to your part's machining process. If you need brass or bronze parts machined, please feel free to contact us for your professional tooling solutions.

Figure 1 Carbide cutting tools for bronze alloy machining give the best results due to three important properties which are wear resistance, hardness and edge retention at high speeds.

Taming The Challenge: Common Issues In Bronze Alloy Machining And Solutions

Some problems inevitably occur in the machining of bronze alloys. If not handled in time, this can affect the quality and efficiency of the workpiece. The following introduces three common problems and their solutions.

Challenge 1: Material "Tool Sticking" and Built-up Edge

Machining bronze, particularly the aluminum bronzes, easily generates tool stickiness and the formation of built-up edge that reduces the surface finish.

Solution: For the C95400 aluminum bronze, the cutting speed is increased from 120 m/min to 160 m/min, using a TiCN-coated tool with adequate cutting fluid for chip removal.

Challenge 2: Heat dissipation and dimensional deformation

Solution: The poor thermal conductivity of bronze makes parts easily deformed by the heat generated during machining.

Solution: Change the feed rate from 0.15mm/r to 0.08mm/r for machining thin-walled parts. Use high-pressure cutting fluid of 0.8 - 1.2 MPa for cooling. Stop during intervals and let the parts cool on their own.

Challenge 3: Achieving Ideal Surface Finish

The requirements for surface finish are very high, such as the need for decorative parts to achieve a mirror surface. Poor parameters are prone to producing textured surfaces.

Solution: Change feed rate to 0.05-0.08 mm/r, use higher spindle speed 2000-2500 r/min, climb mill, and lightly polish after machining.

Figure 2 Machining bronze bushings with surface treatment.It is possible to improve bronze machined parts's performance and appearance by varying the surface treatment.

Why Are Our CNC Machining Services For Bronze Unique?

Among many companies providing CNC machining services for bronze, JS Precision's CNC machining services have three unique advantages in helping you obtain your custom bronze parts more efficiently and of higher quality.

Concentrated Process Database

We have collected a lot of bronze machining optimization parameters, including the cutting speed, feed rate, and tool selection data of different bronze grades, classified and stored.

While processing a certain type of bronze part, we can find the best solution in our database in a very short time.For example, during the machining of the C54400 phosphor bronze bushing, the corresponding PCD tool model and cutting parameters can be retrieved immediately to save debugging time.

Manufacturing-Oriented Design Support

Most customer designs have manufacturability issues, such as very thin wall thicknesses and complicated dead angles that raise machining difficulties and cost.

Our engineers will take the initiative to review the drawing and give improvement suggestions, such as rounding off the dead angles for easier machining, and increasing the deformation resistance for the excessively thin wall thickness properly to improve manufacturability and minimize costs and delivery time.

End-to-end Quality Assurance

We follow a strict quality control system-from the inspection of the incoming raw materials to shipment of the final product.

Percentage composition and hardness of the bronze billet are checked upon arrival for compliance, during machining, it is under constant online monitoring and inspection, and before shipment, every bronze machined parts are fully dimensionally inspected and visually checked for the last time-shipping only those approved to ensure specification conformance.

From Concept To Reality: Where Are Custom Bronze Parts Used?

Custom bronze parts machined through CNC machining find their applications in many industries due to their superior performance. Three major areas are:

Marine and Shipbuilding Engineering: Bronze is a common material for producing propellers, marine valves, and bearings because of its resistance to the corrosion action of sea water and very good wear resistance. We've had a number of well-performed, precision-machined parts for a shipbuilding company.

Heavy Industry and Bearings: Bronze is often used for making high-load, low-speed bearings and bushings, having good self-lubricating properties and high compressive strength. An example of this is bronze bearings machined for a mining equipment company that can support pressure of 500kN.

Art and Architecture: Bronze is also in high demand for intricate decoration pieces, sculptures, and architectural hardware due to machinability and classical aesthetics. We have machined bronze decorative reliefs for a museum, the clear details were well-received.

Figure 3 CNC machining bronze gear. Particularly in clocks, watches, and industrial machinery where low wear and high precision are required.

Practical Case: Achieving 99.8% Dimensional Yield On 500 High-Performance Bronze Bushings

The following is a practical case study of our CNC machining bronze. This will help you intuitively understand how we solve customer problems and produce high-quality bronze machined parts.

Customer Pain Points

A heavy mining equipment manufacturer needs 500 critical bronze bushings in C54400 phosphor bronze. The bushings are used internally in the transmission system of the machine and should have an inner diameter controlled within ±0.01mm.

The instability of the former supplier's parts dimension resulted in maximum deviations of 0.1mm in inner diameter, assembly fit was poor, equipment transmission was disrupted, and the assembly lines were brought to a standstill at least twice a week. Each time, a loss of about $2,000 was incurred. The scrap rate of customers was as high as 5%. A reliable supplier was urgently needed.

JS Precision Solution

In accordance with the requirements of the customer, we analyzed the failure mode of the previously failed parts and found that most of the failure factors were in the clamping method and cutting parameters.

The previously adopted single-jaw clamp resulted in an uneven clamping force that caused the deformation of the bushing during machining, moreover, the cutting parameters had not been optimized for C54400 phosphor bronze, resulting in large dimensional deviations.

These issues can be resolved by redesigning the clamping scheme with a three-point flexible clamp that has added soft pads to ensure uniform clamping force without causing any deformation.

Besides, a selected 12mm diameter PCD turning tool is wear-resistant and appropriate for machining phosphor bronze. The optimized parameters are: cutting speed 180m/min, feed rate 0.12mm/r, and depth of cut 0.2mm, dimensional stability assured.

In the machining process, we used a coordinate measuring machine to check every 10 processed bushings for their inner diameter dimension. If a slight deviation was detected, immediate tool compensation value adjustment was performed to ensure that dimensions always met tolerance specifications.

Our Final Results

In a batch production of 500 bushings, the dimensional pass rate reached as high as 99.8%, and only one was scrapped, which was caused by an inner diameter deviation of 0.012mm.

After the customer used this method, the assembly line downtime was zero, the scrap rate was almost zero, the assembly efficiency was improved by 15%, and the monthly downtime loss decreased by about $8,000. The customer was pleased with the outcome and ordered an additional 300 pieces.

JS Precision specializes in solving the complex problems in CNC machining bronze to provide high precision bronze machined parts for you. If you also face some problems, such as unstable part dimensions, choosing us will provide a reliable solution.

Figure 4 Phosphor tin bronze bushing

Finishing Touches: Which Surface Treatment Is Best For Your Bronze Machined Parts?

Proper surface treatment after the machining of bronze machined parts can enhance both the performance and appearance of the parts. Here are four common methods:

• Passivation: I embodies a dense oxide film on the surface, enhancing corrosion resistance and preserving natural color. Suitable for parts requiring natural texture or appearance.
• Electroplating (Nickel Plating, Chromium Plating): Nickel plating increases the hardness and wear resistance, while chromium plating increases corrosion resistance and provides a bright shine. It is suitable for those parts that require hardness and appearance.
• Sandblasting and Polishing: Sandblasting creates a matte texture, while polishing can achieve a mirror finish for aesthetic needs. It is generally used for artistic or decorative purposes in custom bronze parts.
• Coating: Spray coating provides specific colors and a protective layer. Suitable for parts requiring specific colors or those operating in harsh environments.

Ready to Start Your Project? How to Get Perfect Bronze Parts from JS Precision

Get high-quality bronze parts in four easy steps, with professional support every step of the way.

• Step 1: Provide design drawings and requirements. It requires clear 2D drawings or 3D models, with clear indications of dimensions, tolerances, and material requirements.
• Step 2: Please specify the material specifications and quantity. Please provide the grade of bronze and quantity for us to prepare the material in advance.
• Step 3: Consult our design optimization service. Our engineers will help you optimize the design, improving manufacturability, reducing costs, and shortening delivery time (a free value-added service).
• Step 4: Get a quote and order. We offer a speedy quotation using our effective system. We ensure timely production of the order after confirmation.

If you are ready to start a CNC Machining Bronze project, JS Precision provides full professional support, seamlessly connecting drawing review to parts delivery. Choose our CNC machining services to quickly obtain bronze parts that meet your requirements.

FAQs

Q1: What is the main difference between machining brass and machining bronze?

Brass is easily cut, therefore, the chip breaking is easy, the tool wear is slow, and the machining efficiency is high. Bronze is ductile, hence, chips are longer, tools need to be sharper, and cutting speed has to be higher. This is the main difference in machinability between the two.

Q2: Which bronze alloy is easiest for CNC machining?

Phosphor bronze, such as C54400, is an alloy of bronze that is relatively easy to CNC machine. It has good machinability, smooth chip breaking, high surface finish after machining, and maintains good mechanical properties.

Q3: How can I prevent bronze parts from tarnishing after machining?

The machining of bronze parts can be passivated to form a protective oxide film on the surface, or varnish can be applied to the surface to effectively prevent oxidation and avoid tarnishing.

Q4: What tolerances are you able to hold on bronze machined parts?

The general tolerance of JS Precision for bronze machined parts, in standard sizes, is ±0.025mm. For parts with a simple structure and high precision requirements, even tighter tolerances can be achieved.

Q5: Is it possible to machine bronze without using cutting fluid?

Cutting fluid must always be used when machining bronze. Cutting fluid controls machining heat, improves surface quality, and aids in chip removal. Dry cutting drastically reduces tool life and can cause deformation of the part.

Q6: Can you machine large bronze castings?

Yes, the maximum machining size of large CNC machine tools owned by JS Precision is 3000mm × 1500mm, hence, precision machining of large bronze castings is possible to meet final dimensional requirements.

Q7: What is the lead time for prototyping bronze parts?

For simple bronze part prototypes, JS Precision can complete machining and delivery within 3-5 business days after receiving your drawings and materials. The complex prototypes will take longer.

Q8: Do you provide material certification for your bronze stock?

Yes, if needed, JS Precision can provide original manufacturer's material certification for bronze raw materials, proving that the material composition, hardness, and other performance indicators meet relevant standards.

Summary

Bronze is like a material bridge that spans the past and reaches into the future. Precision CNC machining bronze technology is the key to maximizing its potential in modern times.

From custom bronze parts to mass production of bronze machined parts, JS Precision will be able, with our expertise in the bronze alloy machining, to become your most trusted manufacturing partner.

Take action immediately! Please send in your design files and experience the difference in CNC machining services for bronze processing. Our expert team will get you a detailed quote and manufacturability analysis report within hours.