The anode system plays a critical role in electrocoating by ensuring the stability of the bath liquid’s pH and conductivity. This is achieved through key components, including the anode liquid tank, anode liquid circulation pump, anode liquid flow meter, valves, and anode cover. The anode cover contains the anode tube and ion exchange membrane, while an ammeter monitors the current.
Daily Maintenance and Care
1. Continuous 24-Hour Anode System Circulation
Whether during electrocoating or non-coating periods, as long as the electrophoretic tank is filled with bath liquid, the anode liquid must maintain normal circulation. During production downtime for equipment maintenance, disconnect the anode DC power supply while keeping the system operational.
For extended downtime, drain the existing anode liquid before resuming production and prepare fresh anode liquid to extend the lifespan of the diaphragm electrode and reduce bacterial growth within the anode system.
2. Anode Liquid Color Inspection
Normal anode liquid is clean and transparent. Any color change in a short period indicates potential issues with the anode system.
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If the anode membrane is damaged, the anode liquid becomes turbid, and a layer of bath liquid color adheres to the flow meter.
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If the anode liquid becomes turbid with flocculent material, bacterial contamination is likely.
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If near-colorless transparent anode liquid turns brown or nearly black, it indicates rapid corrosion of the stainless steel anode plate or insufficient anode liquid flow.
3. Regular Sterilization
Add a specific concentration of hydrogen peroxide to the anode tank weekly for sterilization, with each sterilization cycle lasting at least 2 hours. If the system is shut down for more than 2 days, perform sterilization once before resuming operation.
4. Electrode Inspection
If a diaphragm electrode exhibits issues such as leakage, severe core corrosion, poor contact at the core wire joint, or abnormal anode liquid circulation, take immediate action to ensure normal production.
Note: If the diaphragm of a tubular anode is damaged due to workpiece scratching or tank spillage, repair is generally difficult. The affected anode can still be used with the anode liquid circulation system turned off, but this will accelerate anode tube corrosion. If the number of anodes is limited and the circulation system cannot be turned off, use acid-resistant, non-filling adhesive (e.g., free of AB glue or similar fillers) to temporarily patch or seal the diaphragm to maintain anode liquid circulation. Replace the damaged anode diaphragm during scheduled maintenance downtime.
5. Electrode Cleaning
To ensure coating quality, save energy, and extend the lifespan of tubular diaphragm electrodes, remove the diaphragm electrodes from the electrophoretic tank approximately every six months and thoroughly clean them once.
6. Electrode Replacement
Replace the stainless steel tubular electrode core when surface corrosion reaches 20% or when its length is reduced by more than 10%.
7. Electrode Adjustment
During electrocoating production, rotate 316L stainless steel electrodes 180° every 2–3 months, or rotate the diaphragm cover along with the stainless steel electrode, to extend electrode lifespan. During each rotation, check the connection of the stainless steel electrode wires. As the anode tube is consumed due to corrosion, the released iron ions can clog the ion exchange membrane, increasing resistance and anode tube current. Replace the electrode when corrosion reaches a critical level. The typical lifespan of anode membranes and stainless steel electrode tubes is 2–3 years, but the optimal usage period is 1 year.