News and information


What are the reasons for the blackening of the coil?

Release time:

2023-07-25 18:03

1、 Copper wire annealing process
Copper wire annealing refers to a metal heat treatment in which copper wire is slowly heated to a certain high temperature and maintained for a period of time, then cooled at a corresponding rate. Copper wire annealing can effectively reduce hardness, improve machinability, eliminate residual stress, stabilize size, and reduce deformation and crack tendency; Refine grain size, adjust structure, and eliminate structural defects. However, the manufacturer of Beijing Kexun Hongsheng High Temperature Line believes that once the temperature exceeds 50 ℃ during the production process, the required extraction time is insufficient, the SO2 content is high, and the protective gas is impure, which will cause insufficient annealing. After a period of time, the copper wire will be prone to blackening.
2、 Material issues with the insulation layer
Paints can be divided into five categories: impregnating paint, enameled wire paint, covering paint, silicon steel sheet paint, and anti-corona paint. Among them, impregnating paint is used for impregnating motor and electrical coil. The impregnating varnish can fill the gaps and micropores in the insulation system, form a continuous paint film on the surface of the impregnated material, and bond the coil into a solid whole, effectively improving the integrity, thermal conductivity, moisture resistance, Dielectric strength and mechanical strength of the insulation system. Secondly, it also plays a role in heat dissipation. If the insulation paint is soaked, the dried coil can be seen as a whole, and the heat from the inner and outer layers can be easily transmitted, thereby emitting heat. At present, the production process, preparation methods, and technical information of impregnating paint and insulating oil in China are relatively backward. The impregnating paint produced and processed only plays a temporary role, and over time, it will fall and fail.
3、 Usage issues
In the process of using coil copper wire, we often encounter problems such as collision and friction, slow flushing, large amounts of water coming into contact with the coil, use of waste oil lubrication, resulting in residue on the surface of the conductor and damage to the insulation layer, and subsequent oxidation of the conductor during processing.
4、 Technical reasons
Previously, most manufacturers in China used universal copper rods, with a copper content of 99.95%. However, even today, there is still O in copper. The reason is that copper itself is not oxygen free copper, and during the processing, the surface of copper will inevitably come into contact with air and oxidize. By now, advanced production technology for oxygen free copper has been introduced in China, as well as domestically developed oxygen free copper production technology. This has enabled the entire copper wire industry to use oxygen free copper, which undoubtedly greatly improves the blackening problem of copper wires. However, due to the processing of copper rods, especially the use of toughening technology, and the poor storage conditions of finished copper wire cores, the copper wire itself will still have slight oxidation.