Why is copper wire of electric wire and cable black

- Nov 18, 2020-

Copper wire black is caused by a variety of factors, not only the formula problem, but also the copper wire itself in the state, rubber processing technology, rubber vulcanization process, cable structure, sheath rubber formula, production environment and many other factors.


The cause of copper wire blackening:

  1. The area of the wire-drawing emulsion oil pool is small, the return flow pipe is short, and sealed, resulting in slow heat dissipation and high temperature of the emulsion oil.  

  2. It is caused by the annealing of copper wire

  3. Some old factories use annealing cylinder to annealing, so the following reasons will also cause oxidation, blackening

    (1) The annealed cylinder nut is not tightened, after the carbon dioxide or high pure nitrogen leakage;

    (2) When the temperature of the copper wire out of the cylinder is too high, beyond 30℃;

    (3) Draw emulsion maintenance is not enough, PH value is too low;

    These situations are more common in summer when the temperature is high, and the emulsion will lose a little when kept in use, but will lose quickly when the temperature is high. If the new crude oil is not replenished in time, there will be little fat content at this time. In addition to the high temperature, the temperature of the emulsion may exceed 45℃, which will easily cause oxidation blackening.

  4. On the other hand, due to the widespread use of high-speed wire drawing, its speed is improved, the relative heat dissipation time is reduced, bringing a certain space and time to oxidation. Therefore, it is recommended that manufacturers pay more attention to the fat content of the emulsion, use temperature, PH value and other appropriate, the season of yellow mould in spring bacterial reproduction faster, can use fungicidal mildew agent, summer available antioxidant, solve oxidation, blackening and other problems.