Misc. problems in CED (cathodic electrodeposition) coating, p.2

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,

A. CHECK EARTHING.

A. Hi cousin Sathish. More words please -- are you asking a previous poster to clarify the defects they reported so that you can help them? If so, thanks -- attempting to teach is perhaps the fastest way to learn -- but please be more explicit about which posting you are replying to.

If you are looking for help yourself, you can read this thread, as well as threads 23154, 38297, 51966, and 57561. You can search the site using the term "CED defect" for many more threads on the topic.

You can also obtain the two books about CED coating which were suggested higher up on the page. I am not aware of training courses for this subject is India, but hopefully Coatec India [a finishing.com supporting advertiser] or a reader local to you will advise (please tell us your city because some areas of India probably aren't easily accessible to you). Best of luck, but be ready to invest at least a month of hard work in the study of CED defects :-)

Best of luck!

Regards,

A. Dear Sathish, There are lots of defects in CED coating, as it's a very broad area.
But I will explain some defects which are usefully common for all CED Coating lines.
1) Paint Bubbles or CED bubbles :-
First of all CED is a continuous process. It's a non stoppable process. Whenever your conveyor getting stop this paint bubbles will come. this is a wet on wet process i.e. after dipping in ED bath it have mist spray to keep it wet, but some location are not covered in line, which show the Paint Bubbles issue.

A. Hi cousin Abhishek. If you can explain a specific defect, include photos, and give data about the prevailing situation that led to it, I'm sure the readers will be happy to try to help!

Otherwise you can study this posting and its photos and dialogs, the other thread it steers you to (thread 57561, "Pin holes in CED e-coating"), find many other threads on the subject by searching the site for "CED defects", and review the two books which we have mentioned on the subject, and search for your topic on surfacequery.com and scholar.google.com. It's unlikely that anyone is going to write a general tome covering the whole subject of possible CED defects and make it available to us all for free. Good luck, and get back to us with the actual situation you are confronting. Thanks.

Regards,

? Hi Alok. When you say "zinc coated" do you mean hot dip galvanized? Is the metal properly zinc phosphatized after the galvanizing?

Regards,