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Technical Information >> (2B) Rack & Barrel coating process for Electrophretic lacquers
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Methods of Plating
(a) Rack plating
(b) Barrel plating
(a) Rack Plating- Jigs used as Plating Racks
When large volume of production is required, it is convenient to use Plating Racks or Jigs. These jigs are made from copper, Brass or stainless steel.
Jigs have to be designed in accordance with the shape & size of component, tank size, production desired, and current distribution.
Large number of components/ products to coat are individually clipped/ hanged to hooks on jig and than the jig is submersed in lacquer tank which will be connected to charge. The paint particles are drawn to the metal part and lacquer is deposited on the components, forming an even, continuous film over the entire surface, until the coating reaches the desired thickness. Lacquer is deposited by regulating voltage and coating can be either cathodic or anodic.
(b) Barrel plating
The phrase "Barrel plating" refers to method for electroplating small parts in large groups in a rotating barrel. We have developed waterbase electrophoretic lacquer which could be used for Barrel plating. The ability to mass finish smaller parts in a barrel or tub is cost effective. The quality of the finish is similar to rack plating and is typically more economical. The TC30 lacquer is dry and non sticky suitable for barrel coating process.
The normal form of cathode contact consists of a length of heavy insulated flexible cable terminated with a steel cathode knob inside the barrel.
You could use TC30 lacquer for Barrel process. In addition to normal Rack (Jig) coating, TC30 can also be used for Barrel coating. It would be process for sector who wish to coat using electrophoretic waterbase technology.
Use perforated horizontal barrel or open ended tub or bucket or basket type to be immersed in TC30 lacquer bath.
For mass produce thin coating you could dip in tank for few seconds and get even adhesion all over, specially on small components which could not be hanged on jigs and mass coating can be achieved.
Barrel, Tub would be connected to rectifier. Rectifier would touch components to coat. No Rotation of barrel at the time of coating.
(1) Immerse barrel in TC30 lacquer tank and give 30 volts @ 10 seconds.
(2) Stop voltage and now Rotate barrel.
(3) Stop rotating and give 30 volts @ 10 seconds
For Barrel coating you would need to give higher voltage and you can try at 50 volts, 60 volts up to 90 volts.
The three important factors in Barrel coating/ lacquering are weight/ volume, voltage and time. You would need to do various variations to get perfect combination.
Follow above steps for your required thickness coating. Variation of Voltage and number of seconds will change coating results.
Drop barrel, tub in cold water rinse tank. Make sure that cold water temperature is maintained at 10 to 15 0C which will make lacquer dry very quickly and components will not be scratched.
Spread components on tray and stove at recommended temperature in oven.
For more information write to us on
info@shinextechnologies.co.uk
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