Misc. problems in CED (cathodic electrodeposition) coating

A. Hi Jame,
I might be misunderstanding you, but holes in the aluminum substrate are not a CED problem, and I don't think they can be solved with CED coating. If this is one single item, perhaps the holes/pits can be filled with body filler, and the item then painted or powder coated.

If your pretreatment process is causing pits or holes you must fix the pretreatment process. It is never really satisfactory for a factory to plate, paint, or powder coat pitted items.
Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. Check CED bath parameters. Check for bath and anolyte conductivity.

? Hello, cousin Kalidas. if you can give us some info, I think our readers can help! Send some pictures, and tell us what you can.

If you lack sufficient data, the paint vendor, system vendor, or an e-coating consultant may be able to help. Good luck!

A. Dirt can come due to improper cleaning in the pre treatment line. It can be due to dirt in the E-coat tank. It could be due to dirt in the rinse tanks after E-coat. It could be due to dirt being blown around in the oven with the forced circulation. It could be because of one or more than one of the reasons above. And the reasons above could also be due to improper housekeeping or ingress of dirt & dust in your E-coat shop.

Test each and eliminate. I assure you this does not require NASA technology.

A. Check for sludge material in phosphate bath ... if it is high, then desludge it immediately. This will solve your problem.

A. Dear kalidas
Reason of dust ...
1- not proper manual cleaning
2- kod/degreasing FAL pointage down
3- contaminated rinse
4- sludge increase in phosphate tank
5- contaminated DI water..

A. 1. Kindly install filter housing just before CED tank.
2. Use 10 micron filter in CED bath for 10 days and plan to use 10 micron bag filter once in three month.

3. Check CED bath circulation :- it should be properly work, causes of poor circulation paint settling started in bath then generate dust when settling burst.
4. Check incoming material quality first :- it should be dirt free , need & clean material required for ced.
5. Add Solvent as per spec. Less solvent also create dirt or improper finish.

A. Otherwise you can check oven and chamber filter cleaning and air quality.

A. Hi Ale. Sorry, but I don't understand what you mean by dissolution after CED coating. Where, when, and under what conditions is this happening? Can you offer a synonym or expand upon your situation, please. Thanks.

Regards,

A. Sir,
It might be helpful to
- increase bath & anolyte conductivity,
- change the loading position.

Thanks
Surya

A. Hi Phil. I wouldn't expect a body shop to be a fully instrumented coatings science laboratory able to analyze precisely why an aftermarket bumper cover was unpaintable.

... but I would trust people who paint cars day in & day out to be able to reliably paint proper substrates; it will surprise me if anyone can look at the photo and contradict the body shop's assertion.

opinion!   But how did it become your problem unless you told them to use aftermarket parts? If you did, it's on you to prove that the parts are okay. Don't expect the finishing industry, whose reputation gets tarnished when consumers end up with inferior parts when the insurance industry decides that replacement components don't need to be equivalent to OEM parts. All costs associated with inferior aftermarket parts are the fault of the insurance company.

No one should be allowed to substitute inferior parts, and problems like this are only the tip of the iceberg of long-term problems the consumer gets stuck with. Consumer Reports has written repeatedly about this problem of manifestly inferior replacement parts being specified by insurance companies. Good luck.

Regards,

A. Generally CED Paint cures at 150 °C / 20 minutes or 160 °C / 10 minutes Effective Metal Temperature. Oven Air temperature can be set depending on the Material thickness (Component) and time available for Oven curing.

If it is thin material may be 170 °C, 30-40 minutes more than sufficient to cure. In case of thick material like Forging or Casting we may go ahead up to 200 - 220 °C.

Logically we can bake both Powder and E.Coat in the same oven and there will be not any issue in the baking as long as if we meet the baking window criteria.

However E.Coating is a 'wet' process and it is cured in an oven to promote cross-linking. Solvent and Moisture evaporation takes place. Whereas in Powder, Curing causes the particles to melt and also serves as the catalyst for a chemical reaction that produces the desired finish. Both are different process.

During the Hot air circulation sometime loose powder particles deposits on the E.Coat surface before curing causes finish problem. Hence I would not advise Technically. Let us wait for some expert comment please.

Hi. That sounded like "expert comment" to me. Thanks!

Regards,