Q:How to prevent and deal with impurities?
A:Metal impurity control: chemical precipitation, electrolysis, ion exchange resin
Organic impurity treatment: activated carbon adsorption, hydrogen peroxide oxidation.
Preventive measures
Anodes are made of high-purity zinc plates (purity ≥ 99.99%), and polypropylene anode bags are used to prevent anode mud from falling off.
The pre-treatment process is isolated from the electroplating process to prevent the workpiece from carrying acid into the plating tank after pickling (hot water washing + pure water spraying can be added).
Q:What are the abnormal phenomena of plating solution?
A:The glossiness of the coating decreases, plating is missed in the low current area, the coating is brittle and easy to peel off, and the plating solution is turbid with precipitation.
Q:What are the reasons for abnormal plating solution phenomena?
A:Decreased glossiness of the coating: insufficient brightener or excessive organic impurities
Leakage plating in low current area: too low Zn²⁺ concentration or too high pH
Brittle coating, easy to peel off: hydrogen embrittlement (excessive hydrogen evolution) or excessive metal impurities
Turbidity and precipitation in the plating solution: hydroxide precipitation
Q:How to maintain and operate the equipment?
A:1. Maintenance of plating tank and anode
Tab material: PVC or PP for acidic plating solution, stainless steel (316L) or rubber lining for alkaline plating solution to avoid corrosion of the material and contamination of the plating solution.
Anode hook: polish regularly to remove the surface oxide film (such as ZnO) to ensure good conductivity (the oxide film will hinder the dissolution of zinc and cause the Zn²⁺ in the plating solution to decrease).
2. Control of workpiece carry-out
Multi-stage countercurrent rinsing is used to reduce the carry-out of plating solution with the workpiece (the carry-out amount per ton of workpiece is controlled at ≤5L).
The first-stage water washing tank after plating can be recycled and zinc ions can be recovered by evaporation and concentration (such as for pre-treatment pickling tank).
3. Operator training
It is strictly forbidden to touch the plating solution with bare hands (sweat contains impurities such as Na⁺ and Cl⁻), and gloves and goggles must be worn when adding chemicals.
A plating solution maintenance log is established to record each analysis result, addition amount, and processing time to facilitate tracing of abnormal causes.
Q:Comprehensive thinking to ensure the stability of plating solution composition?
A:Source control: Use high-purity chemicals, and the newly prepared plating solution must be verified by Hull cell test plating.
Process monitoring: Daily detection of pH, specific gravity, and main salt concentration, and weekly full component analysis.
Dynamic adjustment: Real-time replenishment through the automatic system, combined with the Hull cell test to predict additive consumption.
Preventive maintenance: Regularly clean the sediment at the bottom of the plating tank, and completely replace the tank at least once a year.