1. If the workpiece is not used after the first chromium plating and the interval between the first and the second chromium plating is not long, the second chromium plating can be carried out by activating the workpiece with 20% sulfuric acid for 1-3 minutes. In chromium plating equipment, low current 5A/dm2 should be used to plating for 2-5 minutes before gradually increasing to normal current density.
2.If the workpiece is not used after the first chromium plating, but the interval is longer. Anodic treatment of 10-20S can be carried out first. Current density varies according to the coating. Hard chromium plating 25-30A/dm2, milky white chromium plating 15-25A/dm2. After the anode treatment, it will be converted to cathodic chromium plating immediately. Start with a small current, then gradually increase the current to the normal current density.
3.If the workpiece has been used after the first chromium plating, it will be soaked in 10%-20% sulphuric acid for 3-5 minutes and cleaned according to 2.
4. The worn plating parts should be grinded flat by grinding machine before oil removal. Then it can be processed in 2.
