Firstly, we must look at the surface of the copper strand flexible: the purchase of round copper braid needs to be viewed from the surface. Usually the round copper braids have a relatively shiny appearance, no obvious damage and scratches, and no obvious oxidation reaction. Meeting the above criteria is the best choice for copper strands.
Then look at the specifications of the round copper braid. The selection of the copper strands need to check the size and technical parameters of the wire. Generally, the wire drawing process of the round copper strands needs to meet the specified range. It is not recommended to exceed the process standard, otherwise it will be regarded as a non-standard twist. The single wire of the twisted round copper stranded wire must meet the uniform and tidy characteristics and conform to the rules of the process and cable standards.
Finally, look at the welding process of copper stranded wire. The purchase of copper stranded wire should also pay attention to whether the welding process is firm, whether the welded interface part is neat, and there is no problem of uneven lines. The welded interface should be repaired neatly, flattened and rounded. The diameter of the welding head is usually not recommended to exceed 0.2 mm. The welding of two adjacent copper strands should be kept at a certain distance and the interval should be even.