Common surface defects in extra-fine steel wire ropes and their causes
During the manufacturing process of extra-fine steel wire ropes, various surface defects often appear, such as missed plating, zinc marks, "bamboo joints", and dezincification. The causes of these defects are
Release Time:
2025-07-02
During the manufacturing process of extra-fine steel wire ropes, various surface defects often appear, such as missed plating, zinc marks, "bamboo joints," and dezincification. What causes these defects? A steel wire rope wholesaler tells you.
I. Causes of Missed Plating
The surface of drawn steel wire adheres to a layer of lubricant or oxide layer. Hot-dip galvanizing on such a surface cannot produce a well-bonded, corrosion-resistant coating. Therefore, before galvanizing, the lubricant or oxide layer on the steel wire surface must be cleaned to expose the silvery-white steel base. Then, a plating aid is applied before hot-dip galvanizing to ensure the zinc bonds firmly to the steel wire substrate. If the lubricant or oxide layer on the surface of the extra-fine steel wire rope is not cleaned properly, missed plating will occur. The general pre-plating surface treatment process is: semi-finished product online - electrolytic alkali washing - water rinsing - acid washing - water rinsing - plating aid - air drying - hot-dip galvanizing - wiping - cooling - wire collecting. Semi-finished extra-fine steel wire rope with an excessively thick phosphating layer that cannot be removed by electrolytic alkali washing; severely rusted semi-finished steel wire where the oxide layer cannot be removed by acid washing; insufficient concentration of alkali washing, acid washing, and plating aid; insufficient temperature of alkali washing and plating aid; excessive speed, insufficient surface treatment time; excessively high FeCI2 concentration in acid washing and plating aid; these factors can all cause missed plating.
II. Causes of Zinc Marks
When the steel wire is withdrawn from the zinc liquid, if the zinc liquid on the steel wire does not flow back into the zinc pot and there is no measure to remove the excess zinc, zinc accumulation will occur on the steel wire, resulting in zinc marks. The causes of zinc marks may be: low zinc liquid temperature, fast withdrawal speed; high iron content in zinc liquid, poor fluidity; excessive zinc slag carried out by the steel wire; unsatisfactory wiping.
III. Causes of "Bamboo Joints"
When extra-fine steel wire rope is withdrawn from the zinc liquid, periodic zinc accumulation appears on the steel wire, resembling the nodes of bamboo, commonly known as "bamboo joints." The causes of "bamboo joints" are: periodic vibration of the steel wire guiding submerged pressure roller in the zinc liquid, improper adjustment of the steady roller after the steel wire is withdrawn, and high resistance to steel wire running.
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2025-07-02
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