Requirements for CNC copper parts design, manufacturing, and surface treatment
Posted on : Apr12，2022 By GREFEE
Requirements for CNC copper parts design, manufacturing, and surface treatment
Copper is known for its naturally beautiful, glossy, and extensive application. After machining, many products are as beautiful as arts. Copper can use to make utensils, decorations, electric energy equipment parts, and even jewels.
Besides, it also has great elasticity and electrical performance, which is suitable for components with high complicities, like EDM electrodes.
Copper has many advantages for mechanical machining parts. It is one of the most widely used metals, which has great corrosion resistance, great electrical conductivity, and thermal conductivity.
We will introduce the marching methods, design tips, and machining requirements for copper and copper alloy. Hopefully, the advice is helpful for your project in saving cost and improving quality.
Cooper machining technology
Pure copper is hard to machine due to its high elasticity, plasticity, and rigidity. The copper alloy improves its machining possibilities, and copper alloy is easier to machine than other metals. Most mechanical machining copper parts are composed of copper, zinc, tin, aluminum, silicon, or nickel. Compared to the machining steel or aluminum alloy, these alloys need less milling force.
CNC millling
Copper alloy can be machined by different technologies. CNC milling is a type of automation process controlled by computers to manage the operations and movements of the multi-point rotating tools. When the tools are swirling and moving on the surface of the parts, it will remove the extra material to complete the required shape and size. Milling can be applied to creating different design features, such as grooves, ports， holes， slots, outlines, and appearance.
Below are tips for copper CNC milling or copper alloy：
- The common milling material is the application groups of the carbide, such as N10, N20, and HSS level.
- You can decrease the milling speed by 10% to prolong the service life of tools.
- When milling the copper casting alloys with casting skin, decrease the milling speed by 15% for cemented carbide cutting tools, and 20% for the HSS tools.
CNC turning
- Another way to machine copper is the CNC turning. The tools stay static, and the parts move to generate the required shapes. CNC turning is a machining system suitable for manufacturing many electrical and mechanical parts.
- CNC turning has many advantages which include the cost benefits, accuracy and improved production rates. When rotating the copper parts, the velocity is essential because copper is a good heat conductor which can generate more amount of heat. As time goes by, this will lead to the damages of tools.
Some tips for copper CNC turning or copper alloy：
- Make the angle of throat of tools within 70° to 95°.
- The angle of throat of the soft copper that is easily to be smeared is 90˚.
- The constant milling depth or reduced angle of the throat can lower the stress on the tools, extend the service life, and raise the milling velocity.
- Increasing the angle between the cutting blades and sub-cutting blades (tools’ included angle) can raise the mechanical load of tools and reduce the thermal stress.
Design notes ：
When designing and machining with copper, many factors need to consider. Generally, copper is used when necessary. Because copper is expensive, it is not often used for producing the whole part. A great design can fully utilize the unique properties of copper.
Reasons for choosing copper or copper alloy：
- High corrosion resistance
- High electricity conductivity and thermal conductivity, and is easy to weld
- High elasticity
- High machinability
correct material grade
- Selecting the correct grade of copper for your applications in designing is essential. For example, it is hard and uneconomical to use pure copper in the mechanical parts. C101（pure copper）has higher electrical conductivity
- due to its pureness (99.99% copper) but poor machinability. While C110 is easier to machine, so it has a better profit. Thus, correct material grades determine the functions in design.
Manufacturabilitydesign
- No matter using what kind of material, DFM is always the first. We suggest you increase the tolerance while keeping the required functions. Besides, it is better to limit the inspection of size and avoid the deep pits with a small radius and limit the number of components.
especially, when resining the copper parts, below are some optimal practice:
- Keep the wall thickness as the 0.5mm
- The size of the largest part of CNC milling is 1200 *500*152 mm. The size of the largest part of CNC turning is 152* 394 mm.
- Undercuts should remain the square profile, full radius, and dovetail profile.
Fine machining copper
After finishing the machining, there are many factors to consider in deciding which technology meets your needs. The first step of the surface cleanses control is part of the CNC machining process. It can be achieved by controlling some parameters to change the surface quality, for example, the nose of the tool radius or tool angle radius.
For soft copper alloy and pure copper, their fineness is related to the nose radius. Thus, to avoid the soft material sticking together and keep the finish, we should decrease the nose radius. A small nose radius can reduce the feeding marks. It is also the first choice for the inserts of the rain wiper compared to the conventional nose radius because it can maintain the surface finish without altering the feeding speed.
You can achieve the finish requirements through the post-treatment：
- Manual polishing — even though it increases the labor burdens but can obtain qualified surface finishes.
- Sandblasting treatment — creates a uniform matte surface and helps hide the defects, which is a helpful post-treatment method.
- Electroplating — some electroplating can enhance the electrical conductivity to brighten the copper surface, the first choice in machining copper parts.
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