Annealer curve characteristics of electrolytically refined tough pitch copper (Cu-ETP) and oxygen free up-cast copper (Cu-OF) for electrical cable wires

Annealing is a critical step during the wire drawing of copper to produce wires with the required ductility and conductivity for electrical applications. In this investigation, the characteristics of commercial annealers for wire drawing of electrolytically refined tough-pitch copper (Cu-ETP) and oxygen-free upcast copper (Cu-OF) wires were assessed through annealer curves with respect to applied voltage and resulting percentage elongation of final products. Experiments were carried out on three M315 Niehoff machines of varying speeds used for medium wire drawing from 2.2 ​mm diameter to 0.66 ​mm and 0.53 ​mm diameters. The results show similarities and differences between annealer curve characteristics of wire drawing machines regarding the required voltage for minimum and maximum elongation of wires without oxidation depending on the type of copper raw material used. In particular, the minimum 18% required elongation of wires was achieved with the same applied voltage irrespective of the machine speed and type of copper. In addition, Cu-OF reached higher maximum percentage elongation without oxidation of the wire compared to Cu-ETP.