CNC Machining Copper

Materials

Descriptions

Copper 101

Copper 101 is the purest grade of copper, containing 99.9% copper. It serves as the base for bronze and brass alloys. C10100, also known as oxygen-free electronic (OFE) copper, is pure copper with an oxygen content of approximately 0.0005%. It is the most expensive among these copper grades.

Copper C110

Copper C110, also known as electrolytic tough pitch (ETP) copper, is easier to machine compared to Copper 101. C11000 is the most popular among all ETP copper grades. C11000 typically contains less than 50 parts per million of impurities, including sulfur. Moreover, they exhibit high electrical conductivity, up to 100% IACS (International Annealed Copper Standard). ETP copper originates from cathode copper, which refers to copper refined through electrolysis. Typically, this process involves filling copper compounds into a solution. Then, applying sufficient power helps in purifying the copper material. As a result, most ETP copper contains fewer impurities compared to other copper grades.

Bronze

It is an alloy of tin, copper, and phosphorus, known for its hardness and strength. Bronze is CNC machined to produce bearings and gears.

Brass

It is an alloy of zinc and copper, renowned for its machinability and hardness. Brass is machined into low-friction and complex parts, including valves, gears, bearings, and locks. Brass components are also used in outdoor applications that may be exposed to saltwater and other contaminants.

Advantages

Disadvantages

In general, most CNC copper parts exhibit good machinability, ductility, and impact strength. They also display high thermal and electrical conductivity, corrosion resistance, and wear resistance. Another advantage of CNC copper parts is their good formability during both hot and cold work. Additionally, CNC copper parts are compatible with a variety of cost-effective surface treatments.

While there are comprehensive advantages, using CNC-machined copper parts also has some drawbacks. For example, not all copper materials can undergo processes like spot welding or metal arc coating.

Different grades of copper have different corrosion resistance. Therefore, some CNC copper parts are susceptible to corrosion in atmospheres containing reactive substances.

Copper has a higher cost compared to some commonly used metal materials, resulting in relatively higher machining costs for CNC copper parts.

Rapid tool wear: Copper has high cutting and thermal conductivity, making it prone to tool wear. In CNC copper machining, frequent tool replacement and maintenance are required, increasing costs and the complexity of process control.

Difficulties in handling thermal deformation: Copper is prone to thermal deformation during machining, especially at high cutting speeds. Proper cooling and cutting parameter control are necessary to minimize heat impact and maintain machining accuracy.

Steps

Descriptions

Select The Right Grade Of Copper

While copper has been successfully used for years, it is one of the more expensive materials. C101 may not have the same machinability as C110 but is more cost-effective. Therefore, the choice of material will depend on the characteristics of your application.

Set The Feed Rate

The feed rate is the speed at which the cutting tool engages with the workpiece. Therefore, it is crucial to set the correct feed rate before machining copper, as it affects the quality, tool life, and surface finish of the copper parts. Furthermore, copper has a high thermal conductivity, so a high feed rate can increase tool wear over time.

Design For Manufacturability

Before machining copper, you must address design requirements and specifications. This will help you achieve the desired functionality for manufacturing copper parts.

Additionally, you can adhere to some design best practices, including reducing the number of part setups, checking dimensions, and avoiding small radii in deep cavities.

Choose Appropriate Tool Materials

Many bronze alloys are easy to machine and softer than aluminum and steel of equivalent strength. This can lead to chip formation and tool wear. Therefore, selecting the right tool material is crucial. High-speed steel is a suitable tool material for CNC machining copper.

Finishing And Post-Processing Options

Polishing:Polishing is a commonly used surface treatment method that involves mechanical grinding and the use of polishing compounds to make the copper surface smooth and remove surface roughness and oxidation. Polishing improves the appearance quality and glossiness of copper.

Plating:Plating involves coating the copper surface with a layer of metal or non-metal material to alter its appearance, provide corrosion resistance, or enhance its functionality. Common plating options include chrome plating, nickel plating, and zinc plating.

Oxidation:Oxidation involves forming an oxide layer on the copper surface to change its color and appearance. Copper can be chemically or electrochemically oxidized to create oxide films of different colors, such as black, blue, green, etc.

Protective coatings:Protective coatings are often used to protect the copper surface from oxidation, corrosion, and contamination. These coatings can be organic paints, varnishes, or special coatings that provide long-lasting protection and aesthetic appearance.

Acid etching:Acid etching is a process that removes oxide layers and impurities from the copper surface. By immersing the copper part in an acidic solution, oxide compounds, and impurities can be removed, restoring the brightness and purity of the copper.

Mechanical engraving:Mechanical engraving involves creating marks and engravings on the copper surface using mechanical tools, creating patterns, text, or decorative effects. Mechanical engraving can add unique textures and artistic appeal to copper products.