pimpacop

Topic: E-Coat Finish

The parts that we are having the issues with are all from vendors. We have are own stamping dept. and this problem is not an issue with our in house parts.

Anyways, if you look at the parts before weld there is dirt on the parts(there is oil on the parts also) after welding the oil is baked off . The paint finish looks like weld splatter all over the back plate but it is not weld splatter, we know that whatever it is its not getting cleaned.

Q.A is saying that it is a Paint Shop problem and I do not believe it is. We paint over 100 parts and this issue is only with 4 or 5 parts and they are all vendor parts.I think whatever is on the oil is getting baked onto the part during weld. you can feel it on the part after weld but its not coming off during pretreatment. Can anyone help with this issue?

Last edited by pimpacop (04/15/2010 - 03:39 AM)

DustinGebhardt

Re: E-Coat Finish

You can easily create some very stubborn compounds when you subject dirt and oils to the high temperatures of welding. I would agree with you that the problem most likely is that the parts are not properly cleaned. I would suggest that you try to clean some parts before welding and see how these come out. If you are doing the cleaning yourself, you should be able to see any cleaning deficiencies with a water break test. After cleaning, the parts can be dipped in water and it should sheet evenly off of the part. If the water beads up or "breaks", the part is still dirty.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

pimpacop

Re: E-Coat Finish

I' m going to try that tomorrow. We had Henkle come in today and they are going to take some parts and run trials to see what its going to take to get them clean. We use Parco 415 in stage 1 &2 at a 5.5-7.0con. at about 135F . Saturday we took it to a 9.0con and it didn't help at all. Then yesterday i sprayed some parts down with Parco precleaner 2978 at 50/50 and that didn't help.Q.A wants to change the con&temps on stage 1,2 but this could cause new problems and to change things because of 4-5 parts # is crazy. We dipped some parts in phosphoric acid for 20mins and the oil still wouldn't come off, it just turned black and we had to rub it off. That is some nasty stuff! We have 2 paint shops and too have the same problem at the same time with both shops only with those parts? Its got to be the vendor...DAMN Q.A.

pimpacop

Re: E-Coat Finish

We have ran the parts through pretreatment and paint without welding them and they all come out good.Whatever is on the parts is getting baked on during welding.Q.A doesn't realize that just because you can't see anything it doesn't mean that its not there!!!

juliachilds

Re: E-Coat Finish

Thats so true

DustinGebhardt

Re: E-Coat Finish

You will probably want to use both an alkaline electro-cleaner and some sort of strong acid, perhaps in a double cycle. Using just the phosphoric acid won't touch any type of oily residue (which is typical of welding fluxes). I would also recommend that you turn up the temperature. With any cleaning process, it is usually dependent on 3 things: Time, Temperature, and Concentration. You've tried increasing the concentration already. Try increasing the temperature. You say you are currently at 135F. This is pretty low for ferrous metals, which are usually run at 160-180F or higher. But if you are using non-ferrous base metals, the 135F may be in range.

The double cycle I mentioned above would look like this:

Electrocleaner

Rinse

Acid

Rinse

Electrocleaner

Rinse

Acid

Rinse


I would also suggest that you contact your supplier of these parts and get an MSDS for the welding rod/wire, plus any flux and rust preventative they are using. Contact those suppliers to see what they recommend for cleaning.

Have you tried solvent cleaning? What about abrasive blasting?

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

pimpacop

Re: E-Coat Finish

Today was very good. We solved the problem that we are having with the parts from our vendor. Both vendors told our Q.A dept. that they were using the same oil as our stamping dept,but when we called the vendors for a copy of the MSDS and a 4oz sample of the oil,they changed their stories. They have been using a additive that helps prolong the health of the Die. The only problem is when you heat this up it acts like a wax and about the only way to get it off is to clean the partrs before welding. Thanks for your input!

DustinGebhardt

Re: E-Coat Finish

That is great news.  Have you seen any improvement since the oil was changed?


-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

joecastro

Re: E-Coat Finish

i am looking for an e-coater preferably in the northern area of Mexcio, does anyone haev any leads?