Copper is a commercial metal that is used throughout the world due to its mechanical and structural properties. This metal offers excellent thermal and electrical conductivity. Also, it resists corrosion as its malleability and ductility allows the metal to be easily worked and fabricated.
There are different grades of metal based on its purity levels. When impurities are introduced during its composition, these impurities will have an impact on its electrical and thermal properties as well as on how it can be fabricated. The copper will also be refined in ways to impact the purity levels in desired ways to provide positive benefits based on the application. Here are the different grades of pure copper that are commercially available.
Commercially pure coppers contain 0.7% in total impurities in its composition. They are extremely soft and ductile. Often, other elements will be added into pure coppers to increase their stiffness. The amount and type of alloys and additives will vary as the diluted coppers will be given a UNS number from C10100 to C13000 based on what elements are added and its impurity levels.
Oxygen Free Coppers
Oxygen free coppers are the purest coppers available. They contain 99.99% copper at a minimum with the lowest level of volatile impurities. This copper is made with induction melting as cathode copper of prime quality is placed into a granulated graphite bath covering as the atmosphere contains low hydrogen and nonoxidizing conditions. This type of copper is highly conductive, as it is commonly used for high vacuum electronics such as glass-to-metal seals and transmitter tubes. Its UNS designation is C10100 to C10200.
Electrolytic tough pitch copper is made from copper that has been refined using electrolysis. This process involves placing copper compounds into a solution as electricity is applied to pass through it to purify the copper metal. Electrolytic copper will contain less than 50 ppm of metallic impurities. It has an electrical conductivity of 100% up to 101% IACS (International Annealed Copper Standard) as it possesses high conductivity and excellent ductility. It is used in most electrical applications including windings, wires, busbars, and cables. The metal can also be worked with hot and cold processes. It has a UNS number of C11000.
Free-machining coppers has sulfur and telluride added to increase its machinability. About 0.5% of these elements will be added. Free machining coppers will be used to create gas welding nozzles, machined electrical components, and the tips of soldering irons as well as torches. Free-machining copper containing sulfur falls under the UNS C14700 designation while copper containing telluride will have the C14500 rating.
Understanding the different grades of copper will allow you to select the right metal that will be cast and machined for the application. It will also help you to determine the copper that will provide the appropriate amounts of thermal and electrical conductivity while being cost-effective to your company.