The manufacturing of copper has changed very little in the past 70 years. Truthfully, it was made in almost the exact same way in the 1930's as it is today, save some minor upgrades. The first step of the process starts with obtaining raw or recycled copper. Methods of acquiring the copper have changed drastically, however. Mining copper has become expensive, which is why most companies have turned to using scrapped or recycled copper from dilapidated buildings. In the case of recycled copper, it must meet certain standards before it is placed into reproduction. The acceptable copper is termed Bright Copper.
Copper Assembly Line
After the copper has been obtained, it is placed into a furnace for melting. Most furnaces have a capacity of 20 tons. That's a lot of copper! In order to refine the metal, the furnace must reach temperatures up to 2400 degrees Fahrenheit. The main purpose of melting the copper is to be able to mold it into desired shapes and also to remove impurities such as a mixture of nickel or zinc alloys. Such metals are filtered out through a process known as fire-refining. In fire-refining, the impure metals become lighter than the copper and float to the surface to be caught on "snags."
So our copper is now a pool of liquid hot metal without impurities. The melted copper is deoxidized in order to remove possible defects during the casting process. From the melting pot it moves into a holding furnace to be poured into a casting pipe which will eventually become the tubing. Once it has cooled and solidified, a large machine called a piercing mandrel drills a hole in the copper, creating the inside of the tubing. Now that we have the basic shape for the copper tubing, it's time to push it out of the cast. A ram forces the copper rod through an extrusion pipe, creating a long hollow tube.
Finally, the tube is forced through metal dies to create the desired size of tubing. When it's at the correct size, it is then cleaned and washed to remove any materials that may have come into contact with the copper. Some mills even disinfect the tubes that will be used for sensitive materials. Now that it's all nice and shiny, it is then packed and shipped off to the retailer or plumbing companies for selling and distribution.