One of the first questions you face when ordering copper wire is whether you want it to be hard-drawn or annealed.
Though both production methods use the same copper as the base material, which one you choose will likely be based on how you plan to use it on the job site. Depending on the application, an annealed copper wire may be more effective than hard-drawn, and vice versa.
Hard-drawn copper is bare copper wire that hasn’t had heat applied to it after it has completed the drawing process through the dies. The more times the wire is pulled through a die, the more “work hardened” it becomes. After a certain point, the wire becomes brittle and could break due to stress.
By forgoing heat treatment, hard-drawn copper has a much higher tensile strength than annealed copper. It also has higher resistivity due to its “hardness.” This is because as the wire is pulled through the dies, the crystalline structure within the copper itself breaks down. As a result, it’s harder for electrons to flow through this copper because they’re too busy being jostled around by the irregular crystals.
Hard-drawn copper is harder to work with because it isn’t flexible, making it hard to use in some applications. However, it’s less expensive because the time to make it is shorter.
Where would you use a strong copper wire that is hard to bend? It’s an excellent choice for situations where flexibility isn’t all that important, particularly in overhead wire applications and straight line cable bus installations. It also works for industrial, railroad, and outdoor installation projects.
Annealed copper goes through the same drawing process as hard-drawn copper but is heat-treated soon after as part of the manufacturing process. The heat makes annealed copper easier to work with, bend and shape, making for a “softer” and less brittle wire.
This version of copper wire is more conductive than hard-drawn, thanks to the heating process the wire goes through after being drawn. The heat performs a reset of sorts to the copper’s crystalline structure, returning it to its original form. The result is a path that allows electrons to flow more easily.
Annealed copper wire is a popular choice across many applications because of its flexibility. It’s helpful when the wire needs to bend around corners, go through conduits, or fit into tight spaces.
Annealing is common in metal manufacturing, including cold rolled steel and steel wire, cast iron, aluminum, brass, and copper.
When metals undergo annealing, they’re subjected to very high temperatures. The high heat changes the metal’s chemical and mechanical properties but doesn’t change its shape. After the metal has been heated for long enough, it needs to cool. Manufacturers can either quench it with water to cool it down quickly or cool it naturally in still air, though this process is slower.
Once the metal is finally cooled, it’s annealed and ready for use.
Although annealed copper wire has many applications, it isn’t a universal product.
If the wire is expected to undergo high tensile pressure, go with hard-drawn copper because it can withstand the physical, mechanical, and other stresses associated with that pressure. The rigid strength of hard-drawn wire also makes it a good fit for straight bus installations and other applications where flexibility isn’t necessary.
Annealed copper wire becomes the better choice when flexibility, malleability, and conductivity are necessary, like in most commercial, retail, and residential applications. This is because there are plenty of turns and tight areas where rigid, hard copper will be much tougher to maneuver and use.
Still have questions about what type of wire is best for you and your application? Kris-Tech’s experts can guide you to the wire that best suits your job, so reach out today and get what you need when you need it.