Pure copper contains quite attractive features such as electrical conductivity and thermal management properties. However, making parts with copper has gone through a long transformation. Metal parts manufacturers have moved from hammers and chisels to modern CNC machines to make complex parts.
We have already discussed the basics of CNC machining in our following article. If you haven’t gone through it, you can read it now.
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So it is not just about processing different materials on CNC machines but taking full advantage of these materials. For instance, incorporating 3D printing for copper and copper alloys enables manufacturers to make metal parts with more complex parts. On the other hand, the global copper market is on the rise. It will reach USD 504.93 billion by 2033.
In this beginner guide for copper machining, we shall explore the basics of copper CNC machining. In addition, why this material is important in making machining parts for different industries? Some of the most common parts of CNC copper are connectors for electronics, and heat sinks for laptops.
What is copper CNC machining?
The machining process for metal parts is almost the same. Yes, the difference is in part design. Imagine, you have a block of copper in your hand and want to make a sophisticated part. Now, you go to a machining center and ask the operator to process that material. He uses different CNC machines to give your workpiece a desired shape. So we can divide this process into three steps:
- Rough Piece of Copper
- CNC Machines
- Machining Process
Hence, we can say that copper CNC machining is a process that incorporates different CNC machines to process solid copper to make complex shapes.
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Stainless Steel Machining
Brass CNC Machining
Properties of Copper
C101 and C110 copper are the purest forms of the copper. Due to electrical conductivity and thermal management properties (around 100% IACS), copper is a very lucrative material for several applications.
However, in machining, copper poses some challenges. Therefore, we shall go through some common copper alloys used for CNC machining.
Challenges in Copper Machining
Pure copper is very delicate so it becomes quite vulnerable during the machining process. This vulnerability leads to poor surface finishing of the part. So machinists use different copper alloys to improve the machinability. You shall read some common copper alloys below.
How can we improve copper machinability?
To improve copper machinability, using copper alloys is the best practice. In this study,you can read more information about the influence of copper and its alloys in machining.
Here are the most common copper alloys and their machining advantages:
Brass (Cu-Zn)
If you add zinc to copper, this alloy will give far better machinability compared to the pre-copper. The zinc proves to be an excellent material for breaking the chip into smaller pieces. Similarly, it also reduces gumming on the cutting tool. However, this alloy decreases both corrosion resistance and electrical conductivity.
Tellurium Copper (Cu-Te)
In Tellurium Copper, a small amount of tellurium is added in copper. This alloy assists in reducing tool wear and enhances brittle chips. Cu-Te is a good choice for high-speed machining. However, it can be a little expensive also.
Lead-Free Machining Brasses
Lead-free machining brasses are good for machining and health both. They do not release any lead. These alloys provide good machining experience due to the following elements such as bismuth, selenium, or tellurium. The aim is to obtain excellent chip formation and reduce tool wear. If you need eco-friendly parts, considering this alloy is a good choice.
It is highly recommended to choose the right alloy for copper machining. For instance, you can select brasses with lower zinc content, bronzes, or tellurium copper. According to research studies on Copper Powders written by Tomasz Skrzekut a small amount of zirconium (Zr) can significantly boost machining. Subsequently, after right copper alloy, try to use carbide speed tools to manage stringy chips.
Latest Developments in Copper CNC Machining
Researchers and material scientists are exploring new ways to accelerate copper machining. For example, the cryogenic machining technique is quite effective (Journal of Manufacturing Process published on 15 April 2024). It incorporates low temperature during the machining process which reduces tool wear.
Similarly, laser-assisted machining is also helping in copper machining. This technique minimizes cutting force and improves chip formation.
Furthermore, Nanoparticle-Based Coatings provides high resistance and significantly enhance protection against tool wear.
Copper Properties and its Common Alloys
| Attribute | 3D Printing | CNC Machining |
|---|---|---|
| Unlimited Material Availability | No | Yes |
| Part Design | Unrestricted by process constraints | Limited by undercut and internal access, tool path and tool type, axis-defined minimum radii, and the need for repositioning mid-task |
| Operator skill | Generally relatively low | Very high |
| Speed of Build | Low setup time, but build time generally takes hours | Can be very high setup and programming time; cutting stages are very fast |
| Surface Finish | Grained, rough, and stepped; features are often blurred | Can deliver very high surface quality by using longer cut times |
| Strength | Often, 10–20 % of native material | Generally, 100 % of native material |
| Cost | Assume a cost of $X | Generally $5X to $10X |
Notes:
- IACS – International Annealed Copper Standard
- W/m*K – Watts per meter-kelvin
- MPa – Megapascals
- % – Percentage
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Surface Finishing Methods in Copper Machining
Just imagine you have asked a CNC machine shop to make you a lot of key chains. They have a good design but the exterior is dull. That is why surface finishing is important. This technique gives a CNC machined part excellent looks. You can say surface finishing makes the final part smoother and shiner.
Copper CNC machining has a diverse range of surface finishing options. Each has its own features. We shall discuss each below.
Pros and Cons of Surface Finishing Techniques
| Finishing Technique | Pros | Cons | Applications |
|---|---|---|---|
| CNC Machining Itself | Economical | Poor smooth finish | Components with less aesthetic finishing |
| Bead Blasting | Creates a uniform, matte finish | Not suitable for high-precision components | Pre-treatment for anodizing |
| Tumbling | Cost-effective Good for deburring |
Limited control over final texture | Parts requiring smooth deburring |
| Brushing | Hides minor machining | Not suitable for high-precision surfaces | Decorative applications |
| Chemical Etching | Precise control over surface texture | Require advanced equipment | Microfluidic components |
| Polishing | Highly reflective | The most expensive finishing technique | High electrical conductive parts |
CNC Machining as Basic Finishing
You might be thinking it funny but basic CNC finishing also uses good feed rate and cutting parameters. These tools give the part a good shape. Yes, indeed, this method is not fine as compared to others.
Mechanical Finishing
In mechanical finishing, bead blasting comes on the top. In this method, surface finishing experts blast the copper part surface with tiny glass beads at high pressure. This method is considered best for non-reflective surfaces. Similarly, this technique is good for components that require anodizing.
Tumbling
In this technique, the finished part is placed in a rotating barrel. There is also abrasive media in it such as ceramic chips. This method offers advantages like smooth finishing. It is also economical.
Brushing
In brushing, an abrasive belt is used to create a fine brushed finish. This technique not only gives good decoration but also hides minor flaws.
Chemical Finishing
Chemical finishing is used to shine the copper part. Through this method, you can achieve a uniform finish and also do microscopic-level removal.
Polishing
Polishing is a highly reflective finishing technique. In this finishing, fine abrasive is used. With buffing wheels, you can get shiner results.
Design Consideration in Copper CNC Machining
In the very beginning of the article, we talked about copper features; such as thermal management and electrical conductivity. However, there are some design considerations to make fully functional copper parts.
Material Selection
Before designing the part, it is recommended to use some alloys. Because pure copper is not good for machining. You can use alloys like brass or bronze.
Machinability
Since copper is soft, this feature can lead to gumming. Therefore, consider adding rounded edges, and larger radii to avoid deep pockets.
Joining Techniques
Soldering and brazing are used to join copper components. However, a good designer must consider the melting points and potential thermal stress. Similarly, ensure good wall thickness for good thread machining.
Electrical Applications
If you maintain a good current flow, make sure there is minimum path resistance. Also, plat the copper with more oxidation. For this, you can use metals like silver or gold.
Thermal Management
Copper is good at heat transfer. However, a designer should design enough surface area. It is to ensure a smooth contact between the heat sink and copper components.
Cost Consideration in Copper CNC Machining
Like any manufacturing process, copper CNC machining also involves a cost factor. Below, we have mentioned some to give you a broad analysis.
Since copper is delicate, it can increase machining time. Ultimately, it will lead to a slightly high upfront cost. If the design is good, you can reduce the cost with machining. Similarly, a simple design will cost less. If you are designing the complex part, the cost will be expensive.
The basic surface finishing incurs low cost. On the other hand, advanced finishing techniques such as polishing will increase the cost.
Why Choose Yijin Hardware for Copper CNC Machining?
Delicate materials need seasoned machining companies to process copper. Therefore, our engineers understand machining material challenges. By using the latest CNC machines, Yijin Hardware provides an extensive range of materials and offer high-precision machining. Subsequently, we offer the best surface finishing for finished parts and ensure on-time delivery.
