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Electrical and thermally conductive, ductile, corrosion resistant—that’s copper, the third most used material in the industry. Primarily, the electronics industry leverages these properties, but copper’s versatility extends to various mechanical applications. Most of these applications require the precise machining of copper to transform its raw form into a functional product.
This article sheds light on all that goes into manufacturing copper products; the complex CNC machining techniques, the essential tools, the challenges encountered, and the broad range of applications that benefit.
CNC Machining: The Ultimate Choice for Copper
CNC Machining Copper refers to the use of precise numeric control machining (CNCs) to cut, size, and shape copper. Since copper is inherently ductile and conductive, it demands machining that can handle the material with exactitude and consistency – CNC machines meet these requirements adeptly.
CNC machining makes sure that dimensional specifications are met and the integrity of copper’s physical properties is maintained throughout the process. This is crucial because even minor deviations can significantly affect the performance of copper parts, especially in electrical and thermal applications.
Moreover, the diverse applications of copper—from electronic components to mechanical assemblies—require versatile machining capabilities. CNC machining provides this versatility by allowing for complex shapes and fine details that are required in these technical fields.
Common CNC Machining Techniques for Copper
Here’s a brief overview of popular Copper CNC machining techniques:
CNC Milling employs rotary tools to cut copper into precise shapes and sizes. This method is particularly useful for making slots, holes, and intricate surfaces that require high precision.
CNC Turning is used for making cylindrical copper components by rotating the copper workpiece against a stationary cutting tool. This process is beneficial for making precision parts such as pins, rods, and bushings used in electrical and mechanical systems.
Copper Alloys for CNC Machining
Copper, similar to other metals, is available in different grades and compositions. Each one has its unique characteristics and caters to specific applications.
Pure Copper/Electrolytic Copper
Pure copper, often called Electrolytic Tough Pitch (ETP) copper, contains a minimum of 99.9% copper. After the copper has been extracted from ores, melted, and purified up to 99%, it further goes through an electrolysis process, where it is fully purified.
Since such copper is obtained at the cathode of the electrolytic, it’s often called cathode copper.
It’s highly conductive and thus ideal for electrical applications, such as conductive wiring and electrical components. However, softness can make machining challenging. Commercially, the copper series between UNS numbers C10100 and C13000 is considered. Among them, C11000 (Electrolytic Tough Pitch Copper) is the most common grade of pure copper. It’s 99.95% pure and used for making electrical wires.
Oxygen-Free Copper
Oxygen-Free Copper (OFC) is highly pure and refined to have no oxygen content. This absence of oxygen enhances its electrical conductivity and corrosion resistance. It suits high-quality audiovisual components, semiconductor bases, and vacuum-sealed conductor parts.
OFC is also preferred in environments where hydrogen embrittlement must be avoided. Its two common grades are:
- C10200 (Oxygen-Free Copper) is the purest of all. It has about 0.0005% oxygen and is known to be expensive.
- C10100 (Oxygen-Free Electronic Copper) has around 0.001% oxygen content, and high electrical conductivity, comparable to those electrolytic copper.
Machining-Free Copper
Machining-free copper is copper alloys with trace amounts of additives (like tin, phosphorus, sulfur, zinc, tellurium, and nickel) to improve machinability. This copper is ideal for making mechanical parts that require extensive machining. For instance, connectors or parts with detailed threading.
Ideally, the introduction of machining-free copper was to improve machining while keeping conductivity constant. However, due to additives like lead, the conductivity does fall compared to pure copper.
Besides brass and bronze, some popular grades of free-machining copper include C14500 (Tellurium Copper), C14700 (Sulfur Copper), and C111.
Benefits of CNC Machining Copper
The CNC machining aids in shaping and forming the metal to the desired shape. But in the end, it’s the metal’s natural properties that make it useful. Some key ones include:
Electrical and Thermal Conductivity
Copper is second only to silver in terms of electrical conductivity. That’s why it’s my constituent of all electrical appliances and circuit boards. Its thermal conductivity is also leveraged in heat exchangers.
Corrosion resistance
Copper exhibits exceptional resistance to corrosion, which is evident in iconic structures such as the Statue of Liberty, which contains about 80 tons of copper. Moreover, its bactericidal and fungicidal properties make copper ideal for fabricating handles and doorknobs in public spaces.
Recyclability
An estimate shows that almost 80% of mined copper is recycled and still in use today. Copper also retains its properties even after multiple recycling processes.
Challenges in CNC Machining Copper
A metal whether hard or soft, is always a challenge to machine. So, copper is no exception. When machining copper, we often encounter these challenges:
Work Hardening
Work hardening occurs when copper becomes tougher and more brittle due to deformation during machining. To mitigate work hardening, use sharp tools and high cutting speeds.
Burr Formation
Burr formation is common in all metal machining jobs. Rough edges are formed as small material pieces remain attached after the cutting operation. To avoid that, sharp cutting tools with optimized cutting speeds can help. In addition, deburring can be carried out post-cutting.
Limitations in Processing Techniques
Not all copper materials can undergo welding processes like spot welding or arc welding. These limitations can restrict the manufacturing options for copper components.
Considerations When CNC Machining Copper
Whenever you’re to machine copper with any set of tools, these basic considerations must be kept in mind:
Grade of Copper
The choice of grade needs to be based on the application and desired characteristics. For applications that require high electrical conductivity, use pure copper (C11000). However, for mechanical parts where easier machining is required, free-machining copper provides better machinability and cost-effectiveness.
Cutting Speed and Feed Rate
The cutting speed and feed rate must be set considering copper’s softness and high conductivity. A higher feed rate minimizes the time the tool is in contact with the material, reducing heat buildup but it increases tool wear. So, a trade-off has to be made that tool life is minimally affected as well.
Machining Tool
The choice of tool material and geometry depends on the copper grade being machined. High-speed steel (HSS) or carbide tools (N10, N20) are effective for all copper grades.
For softer coppers that smear, tools with an edge angle close to 90 degrees are best as they minimize material adherence and improve cut quality.
Maintaining a constant cutting depth and optimizing the tool edge angle can reduce tool stress. In addition, increasing the angle between the main and secondary cutting edges can also help manage mechanical forces better and reduce thermal stress on the tool.
Designing for Manufacturability (DFM)
The design part should be made per DFM principles. Optimize design tolerances while retaining essential functionality. Avoid complex features like deep pockets with small radii that can complicate machining and increase costs. Maintain a minimum wall thickness of 0.5 mm and consider the size limitations for CNC milling (up to 1200 x 500 x 152 mm) and turning (up to 152 x 394 mm).
Designs should also account for the feasibility of undercuts – use square, full-radius, or dovetail profiles to simplify machining.
Surface Finishing Techniques for CNC Machined Copper Components
Metals have that lustrous feel, but machining somehow dulls that characteristic. To regain that shine, machining is always followed by a surface finishing technique/s. In the case of copper, these finishing techniques are popular:
Electropolishing
Electropolishing uses an electrochemical solution to polish, passivate, and deburr copper surfaces. It improves the material’s aesthetic and corrosion resistance by removing a thin layer (0.0025mm to 0.064mm) of the surface.
This technique is for components that need a high gloss finish or enhanced corrosion resistance, for instance, medical devices, and food processing equipment.
Electroplating
Electroplating involves covering the copper component with a layer of another metal via an electrochemical process. This process is for protecting the copper and adding surface properties without affecting the conductivity. One common example is the tin plating of electrical connectors to improve solderability.
Media blasting
Media blasting (or abrasive blasting) propels a stream of abrasive material against the surface of the copper to smooth it, remove imperfections, or create a specific surface texture. Common media include beads, soda, or sand.
It’s frequently used to achieve a matte or textured finish that can improve the grip or aesthetic of the part.
Applications of CNC Machined Copper Parts
Copper is a ductile, and highly conductive material. About 60% of applications of copper are within the electronics segment, but it’s also an integral part of most mechanical applications.
Mechanical Applications
| Applications | Specific Parts Made with Copper |
| Heat Exchangers | Tubes, plates, finned tubes |
| Automotive | Radiators, cooling systems, brake tubes |
| Industrial Machinery | Bearings, bushings, hydraulic tubing |
| Welding Equipment | Gas welding nozzles, welding torch components |
| Plumbing | Pipes, fittings, valves |
Electronics
| Applications | Specific Parts Made from Copper |
| Electrical Systems | Bus bars, grounding bars, electrical contacts |
| Electronics | Connectors, terminals, PCB traces |
| Telecommunications | Antenna components, coaxial cables |
| Power Distribution | Switchgear components, circuit breaker parts |
Other Industrial Uses
| Industry | Applications |
| Renewable Energy | Solar panel bus bars, wind turbine connections |
| Medical Devices | Surgical instruments, diagnostic device components |
| Manufacturing | Custom tooling and fixtures |
Choose RichConn for Copper CNC Machining Services
Need any custom copper parts? Or designing a product that requires precision Copper CNC machining? Explore Richconn’s comprehensive CNC Metal Machining Services. We specialize in CNC turning and milling, catering not only to copper but also a variety of other metals.Submit your design specifications to receive an instant quote. Contact Richconn Now and start your machining journey with us!
FAQs
What is the best copper to machine?
Ideally, machining-free copper, which has additives, is easier to machine than other copper types. Among the pure coppers, C10100, also known as C101, is a cost-effective and easy machining option compared to C100.
Is machining copper difficult?
Copper machining is not necessarily difficult, but it does present certain challenges. The grades of copper vary widely in their properties; many are soft and highly conductive, which requires careful selection of machining parameters and tools. These must be chosen to ensure that the natural properties of copper are not altered during the machining process.
What cutting tools are best for CNC machining copper?
Cutting tools made of high-speed steel (HSS) or carbide (grades N10 and N20) are best for cutting a soft and ductile material like copper.
