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Radmot Mar 22, 2023 9:59:17 AM

Copper machining – why is that material so interesting?

Copper – among others, like steel – is one of the key strategic materials for production in many industries. That material is known for centuries, mainly because copper is a main component of bronzes – hence the name: the Bronze Age. The Latin name of copper (Cuprum) shows its roots – it can be translated as "the material from Cyprus”, where in antiquity ages was mainly mined. Although today the biggest copper mine is in Chile (Chuquicamata), other significant mining sites are located all over the world, also in Poland (Lubin-Głogów Copper District in Lower Silesia). 

Copper is a surprisingly common metal – is used for the production of current (coins in particular; earlier: Dinars, currently – eg. Euro and Euro Cents), electronics, and telecommunication (wiring is made mainly from copper due to its electrical conductivity), construction (pipes, especially to the CO are made of that material) and automotive industry. It is worth mentioning that copper is also used in fireworks – in the explosion burning copper creates colorful sparks.


What does the contemporary production of copper look like?

The copper stone is achieved by processing copper pyrite. The material at the beginning of its processing is slagged and separated from the copper stone. Further treatment is focused on achieving raw copper – up to 98% of purity. The remaining 2% are base and precious metals (from iron and zinc to silver and gold). In the process of electrolysis these elements are separated from the main material and the effect of that stage of production is a material called "pure copper”, with a purity close to 100%.

What are the copper properties?

Among many important properties of copper, it is worth highlighting the following:

  • very good electrical and thermal conductivity – almost as good as silver, and better than gold. That is why copper is widely used in the electrical and electronics industries. It is calculated, that the average car contains over 22 kilograms (approx. 48 pounds) of pure copper,
  • UV resistance – copper is often used for UV isolation,
  • corrosion resistance – that is why copper is often used in places exposed to corrosion agents, like salt water. This is one of the reasons why the exterior of the Statue of Liberty in New York was made of that material (approx. 80 tons of copper were sailed from the Visnes mining site in Norway to NY),
  • very good machining properties and plasticity – that is why that material is often used in industry-grade CNC milling and CNC turning machines,
  • machined copper parts and tools to not generate sparks – can be used safely in a dangerous environment and explosion hazard zones,
  • bactericidal, viral, and fungicidal properties – it makes copper a perfect material to produce antibacterial door knobs and door handles (especially in public places, clinics, and hospitals), sometimes is used in specialized wound dressings (among with silver) and in agriculture (eg. for "copper spray” for some types of crops due to its fungicidal properties), 
  • copper is easy to recycle – it is estimated that over 80% of so far mined copper is in continuous use. That material does not lose its properties even after many processes. It is worth mentioning, copper is called "a material of the future and new technologies” – without that element, the 3rd and 4th industrial revolutions would not take place due to its usage in electronic devices.


What is copper machining?

Pure copper is very hard to machine (just like pure aluminum, like type 1xxx) due to its ductility and plasticity. For that reason, the most machined material are copper alloys with elements like:

  • zinc (Zn), tin (Sn), aluminum (Al), and silicon (Si) – that provides good quality (and repetitive) shavings, 
  • lead (Pb) and selenium (Se) – that gives a copper alloy similar machining properties to automotive steel. 

During the machining process, copper alloy shavings do not stick to the cutting tool. Such can create problems with an increase in temperature and unwanted forces during the process and decrease the quality of the surface finish and lead to faster tool wear. 

It can be achieved by maintaining good work parameters (eg. good feed rate of proper heat dispersion system). Machining-wise, the copper alloys have similar properties to hardened steel, titanium allies, or white cast iron. 

Copper alloy machinability classifies the Universal Machinability Rating (UMR). The base point of that methodology is the machinability of brass CZ121 ≈ MO58 (CuZn40Pb2). It is worth mentioning that some sources use other material as a basepoint – free-cutting brass: CuZn39Pb3. UMR classifieds things like:

  • shape and size of shavings, 
  • utilization of high-speed spindles in milling copper, 
  • required force and other milling and turning parameters, 
  • precision and the quality of the finished surface. 

Said classification is commonly called "the copper machinability index”.

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What are the types of copper alloys (based on UMR)?

Based on the UMR we can highlight three groups of copper alloys, based on their machinability:

  • UMR 60% and more – the most machinable copper alloys, with the addition of lead (Pb), tellurium (Te), and sulfur (S),
  • UMR between 30 – 60% – alloys with good machinability characteristics. Milling and turning can produce longer shavings,
  • UMR below 30% –  high-performance alloys but problematic during machining. Can create longer shavings that stick to the cutting tools and can cause faster tool wear. Also can generate higher temperatures and require lower working speeds and better heat dispersion systems.

Most copper-based materials for the electrical and electronic industries have a very low UMR score (between 18 and 30). On the other hand – rarely require machining. It is worth mentioning that copper CNC machining services are very popular in the optical industry.

What are the main applications of copper in industries?

Currency copper is used mainly in the electrical industry for the production of a vast variety of wiring. We can estimate that almost 60% of available copper is currently in use that way. Also, copper alloys are used in applications such as: 

  • construction (eg. for covering buildings with a copper plate or delivering electricity), 
  • parts for machines – over 15% of worldwide copper resources is used to produce said elements (eg. copper sleeves), 
  • waterworks – due to its antibacterial properties. It is worth mentioning the first waterwork was built in ancient Egypt (over 4000 years ago) and their pieces are to this day in good shape (can be found in the exhibition in National Museum in Berlin), 
  • housing for the nuclear wastes – their lifetimes are estimated for over 100 thousand years 

Copper is a very popular material and can be used in many applications. Also: post-processing of that metal opens many possibilities to increase its resistance to wear and other corrosive agents. 

That is why ordering copper components can be tricky and require additional knowledge. The expertise of professional CNC machining operators can help to prepare that process cost-effectively for clients.

Copper machining services in RADMOT

At RADMOT, we can offer CNC milling servicesCNC turning services as well as many additional services, including washing, aluminum anodizing, laser marking and assembly.

Contact us and tell us what you need. We have been providing CNC services for almost 40 years. Our quote is completely free. And if you have any doubts about what technology will work best for you, our expertise is at your service.

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