As we all know, wires and cables are designed to carry electric current mainly. However, not everyone knows how are they produced. A conductor is a material in which electricity can flow through. Electrical conductors are made up of metals such as copper, aluminum, etc. A certain number of wires with a certain diameter are required to form the conductor and to obtain these wires, standard conductor rods are drawn.
Step 1: Wire drawing
Wire drawing is the first step in the manufacturing process of a conductor. Wire drawing is a progressive process in which the metal is stretched and formed from a larger diameter to smaller diameters through a successive series of precision dies and drawing wheels which pull the wire. And this is processing with a lubricating and cooling system that increased the life of the dies and prevents the wire from overheating.
The main purpose is to meet cable production requirements. Although similar in process, drawing is different from extrusion, because in drawing the wire is pulled, rather than pushed, through the die. Drawing is usually performed at room temperature, thus classified as a cold working process. The drawn wire is not suitable for direct use as it has become harder after stretching and thinning.
Step 2: Annealing
After wire drawing, the wire is extremely brittle and can easily be fractured if flexed. Since finished copper wire must be flexible, the wire is softened or annealed at this point. In this process, copper wires undergo a heat treatment called annealing. Process annealing will afford stress relieving of the wire and cable. This process will reduce the brittleness which is in favor of cable production and installation. It also enlarges the elongation rate and decreases the conductor resistance and in return enhance the conductivity. In annealing, atoms migrate in the crystal lattice and the number of dislocations decreases, leading to a change in ductility and hardness. Copper can be cooled quickly by quenching in water, unlike ferrous metals, such as steel, which must be cooled slowly to anneal. The video showing wire drawing and annealing process can be found below.
Rados IPQC – SIP
The elongation rate, tensile strength and conductor resistance of round copper wires or round aluminum wires shall comply with the requirements of a specific standard or order requirements. Rados conduct standard IPQC ( In Process Quality Control ) and SIP ( Standard Inspection Procedure ) to make sure the quality is qualified. Below are examples of IPQC conducted and the SIP document used in the wire drawing and annealing process.