Use copper design, processing and surface treatment requirements

Copper is a truly versatile metal. Copper has a naturally beautiful, shiny finish, making it ideal for artwork, kitchenware, kitchen backsplashes, countertops, and even jewelry. It also has excellent materials and electrical properties, and is suitable for complex engineering parts, such as EDM electrodes.

There are many benefits to using copper for machined parts. Copper is one of the most widely used metals in the world, with high corrosion resistance and good electrical and thermal conductivity. In this article, we will discuss copper and copper alloy processing methods, design considerations and processing requirements, which are not only aesthetic benefits.

Pure copper is difficult to process due to its high ductility, plasticity and toughness. Alloyed copper improves its workability and even makes copper alloys easier to process than most other metal materials. Most machined copper parts are made of alloys of copper and zinc, tin, aluminum, silicon, and/or nickel. Compared with processing steel or aluminum alloys of the same strength, these alloys require much smaller cutting forces.


Copper alloys can be processed using various techniques. CNC Milling Parts is an automated machining process that uses computer control to manage the movement and operation of multi-point rotary cutting tools. When the tools rotate and move on the surface of the workpiece, they will slowly remove the excess material to complete the desired shape and size. Milling can be used to create different design features such as grooves, notches, grooves, holes, slots, contours, and planes.


Here are some guidelines for CNC milling of copper or copper alloys:

1. Common cutting materials are carbide application groups, such as N10 and N20, and HSS grades
2. You can reduce the cutting speed by 10% to extend the tool life
3. When milling copper casting alloys with cast skin, reduce the cutting speed by 15% for cemented carbide tools, and reduce the cutting speed by 20% for HSS-level tools

Another technique for machining copper is CNC turning, where the tool remains stationary while the workpiece moves to produce the desired shape. CNC turning is a machining system suitable for manufacturing many electronic and mechanical parts.

There are many benefits to using CNC turning, including cost-effectiveness, precision, and increased manufacturing speed. When rotating copper workpieces, careful consideration of speed is particularly important, because copper is an excellent heat conductor, it generates more heat than other materials, which will increase tool wear over time.

The following are some techniques for CNC turning copper or copper alloys:
1. Set the blade angle of the tool in the range of 70° to 95°
2. Softer copper, which is easy to be smeared, requires a cutter blade angle of about 90˚
3. Constant cutting depth and reduced tool edge angle can reduce the stress on the tool, improve tool life and cutting speed
3. Increasing the angle between the main cutting edge and the secondary cutting edge (tool included angle) can make the tool bear higher mechanical load and lead to lower thermal stress


Design considerations
When designing parts made of copper, many factors need to be considered. In general, you should only use copper when necessary, because copper is expensive, and it is usually not necessary to produce the entire part with copper. A good design can use a small portion of copper to maximize its unusual characteristics.
The following are some common reasons for choosing copper or copper alloy parts:
1. High corrosion resistance
2. High electrical and thermal conductivity, easy to solder
3. High ductility
4. Highly machinable alloy
5. Choose the right material grade

During the design phase, it is very important to choose the correct grade of copper for your application. For example, using pure copper for complete mechanical parts is not only difficult but also uneconomical. C101 (pure copper) has higher conductivity due to its purity (99.99% copper), but has poor processability, while C110 is generally easier to process and therefore more cost-effective. Therefore, choosing the correct material grade depends on the characteristics that are critical to the design function.

No matter what material you use, DFM should always be the top priority. At Fictiv, we recommend that you relax the tolerances as much as possible while retaining the functions required by your application. In addition, it is best to limit size inspection, avoid deep cavities with small radius, and limit the number of parts set.

No matter what material you use, DFM should always be your first choice. We recommend that you relax the tolerances as much as possible while retaining the functions required by the application. In addition, it is best to limit dimensional inspections, avoid deep grooves with small radii, and limit the number of parts set.

In particular, when designing copper parts, here are some specific best practices:
1. Keep a minimum wall thickness of 0.5 mm
2. The maximum part size for CNC milling is 1200 * 500 * 152 mm, and the maximum part size for CNC turning is 152 * 394 mm
3. For undercut, keep square contour, full radius or dovetail contour

After processing, there are many factors to consider when deciding which process is best for your needs. The first step in surface finish control is in the CNC machining process. Some CNC machining parameters can be controlled to change the surface quality of the machined parts, for example, the tool nose radius or the tool corner radius.

For soft copper alloys and pure copper, the quality of finish depends directly and seriously on the nose radius. The radius of the nose should be minimized to prevent the application of softer metals and reduce the surface roughness. Doing so can create a higher quality cutting surface, because a smaller nose radius can reduce feed marks. Compared with traditional tool nose radius tools, wiper inserts are the tool of choice because they can improve the surface finish without changing the feed rate.

You can also achieve the part finish requirements through post-processing:
1. Manual polishing-although it is labor-intensive, but polishing will produce attractive surface gloss
2. Medium sandblasting-this will produce a uniform matte surface and hide small imperfections.
3. Electrolytic polishing-because of its incredible electrical conductivity, it makes copper bright and is the best choice for finishing copper.