Schematic diagram of the electrodeposition process
Electrodeposition equipment
1. Conveyor
High-volume production enters the tank at a 30° angle using an overhead conveyor. Energy saving space, free and power conveyor belts provide 90° vertical incidence sometimes combined with bulk paint.
2. Preparation of metal
Electrophoretic coating equipment mostly uses seven to nine grades of zinc phosphate. Iron phosphate is also widely used. Non-ferrous metals use special pretreatment methods.
3. Box shell
The box housing provides a security and contains the power supply and transport. De-energize the system at any point of entry and exit.
4. Dip tank
In the latter case, the tank operates continuously (conveyor or coil) or batch-fed. Use the "power and freedom" conveyor belt. Workplaces are usually fully submerged below 15cm. There is a 15 cm gap on the surface. The tank shell provides about 3 minutes of workplace accommodation, while the coating of the tank and coil is done in seconds.
5. Rectifier tube
Use a DC power supply with less than 5% ripple factor over the entire range.
6. Electrodes
Most electrophoresis tanks are lined with an epoxy coating about 10mm thick. In this case, the tank, transport, commodity, etc. are the basis: only the electrodes, inserted into the painted surface, have opposite polarity (heat). Inserted electrodes are protected by plastic grids. If it is the ions that need to be collected (acid or base group), then an electrode separator tank fills the membrane with the ions through a process called electrodialysis. The cell itself can be very desirable as a counter electrode, except for the electrolyte separation.
7. Stir
Electrocoats up to 500,000 liter volume contain 10 to 20% by weight solids and approximate bath water viscosity. Ejectors and other agitation devices are used to move the entire bath volume within 6 to 30 minutes to prevent settling of solids.
The residence time in the bath is described as "turnover".
For example, a tank with an average volume of 100,000 liters has a fill volume of approximately 10,000 kg of paint solids. The stirring capacity reaches 10000 kg at one time. Added solids (feed), from 10 working days up to 10 months, depending on commodity structure and production rate. At this time, according to the laws of probability, much of the original filling material is still in the tank. Therefore, considerable pumping stability is required.
8. Temperature control
Most tanks operate in the temperature range of 75 to 95°F. Almost all of the electricity needed to convert between power and fanning energy into heat needs to be removed with a chiller.
9. Ultrafilter
The saving of paint and the removal of dissolved impurities is accomplished by ultrafiltration, using membranes. Permeable to water, salt and substances less than 300 molecular weight. Ultrafiltrate (osmosis) is used for usually three spray rinses and sometimes one dip rinse, followed by a deionized water rinse.
10. Paint filter
Filter bags, wound filters and indexed filters 5 to 50 micron pore size.
11. Paint makeup
In formulas 27.1 and 27.2, makeup is actually the last step in the manufacturing process. Water-based paints are made by mixing the contents of the can with all the paint ingredients needed.
12. Deionized water
Evaporated or lost water is replaced by 75,000Ω-use cm water, which is also used as a final rinse.
13. Baking or curing
Most electrodeposition coatings require a 20-minute bake at 350°F. However, reduced bake materials are available; even marketed ambient cure materials.
