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Why does the copper wire of the wire and cable turn black?
Latest company news about Why does the copper wire of the wire and cable turn black?

In many cases, the wires we have used for a long time will appear black. What causes it?



(1) It may be that the area of ​​the wire drawing emulsified oil pool is small, the return pipe is short and sealed, which results in slow heat dissipation and high temperature of the emulsified oil.


(2) It is caused by copper wire annealing. Firstly, tap water and groundwater are generally used for cooling water for continuous cooling. As the water quality varies from place to place, the PH value of water quality in some areas is low, only 5.5~5.0 (normally 7.0~7.5). The anti-oxidant oil film has been cleaned off, and the annealed copper wire is easy to oxidize and turn black; the second is that the finished copper wire drawn by the ordinary wire drawing machine is annealed on another annealing line, and the cooling water does not use antioxidants. Anti-oxidation time Short, oxidation and blackening will soon appear;


(3) Some old factories still use annealing cylinders for annealing. The following reasons can also cause oxidation and blackening: one is that the annealing cylinder nut is not tightened, and the gas leaks after flushing carbon dioxide or high-purity nitrogen; the other is out of the cylinder. The temperature of the copper wire is too high, exceeding 30℃; third, the drawing emulsion is not maintained enough and the PH value is too low; these situations are more common when the temperature is high in summer, the emulsion will be lost if used continuously, and it will be lost when the temperature is high Faster, if the new crude oil is not replenished in time, the fat content is small at this time, and the temperature is high, the temperature of the emulsion may also exceed 45°C, which will easily cause oxidation and blackening.


(4) Another situation is that due to the current widespread use of high-speed wire drawing, the speed has increased, and the relative heat dissipation time is reduced, which brings a certain amount of space and time to oxidation. Therefore, it is recommended that the manufacturer pay more attention to the fat content of the emulsion The conditions, temperature, pH value, etc. are appropriate. Bacteria multiply faster in the yellow mold rain season in spring. Anti-bacterial and anti-fungal agents can be used. Antioxidants can be used in summer to solve oxidation and blackening problems.




1. The deformation of the finished mold is too small;
2. The periphery and front of the mold insert are not well sealed.




Add a rubber pad in the exit direction of the finished mold, and then screw the finished mold to solve the problem of oil leakage.
The deformation of the finished mold is too small, which is a common mistake. The deformation of the single mold requires a small amount of deformation, and the pressure generated may be greater than the yield limit of the metal, and then the plastic deformation can be realized, the size can be stable, and the surface of the single wire can be stable. There will be light from cold drawing.



The above are all the reasons for the blackening of wires and cables and how to deal with them. If you have related questions and needs, please contact us!

Pub Time : 2021-08-09 10:00:50 >> News list
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