E-Coat Paint
E-Coat Paint
(OP)
My company makes link rods for the automotive industry and we're having problems with our ecoat painting on these link rods. We used to have problems with the paint "blistering" but that has diminished and now we're having a problem with the paint looking as though it builds up on the side of the part, making it have the pattern of tiger stripes. But its not down the entire part and its only on one side of the part. You can feel the defection with your finger and can only see it with good lighting. It also does not seem to be consistent with the direction and angle that the rods are placed on the racks before they're dipped.
Has anyone else ever come across this problem and what would be a good direction towards solving it?
Has anyone else ever come across this problem and what would be a good direction towards solving it?





RE: E-Coat Paint
RE: E-Coat Paint
RE: E-Coat Paint
Brief overview here:
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As a consumer, I think I've seen tiger stripes, on link rods, before, so maybe it's an old problem. As noted, your coating supplier may have expertise.
My guesses:
Electric field nonuniform, possibly due to masking by other parts or the racks.
Deposited film being disturbed before baking, e.g. rough motion during, er, un-dipping.
Bath contamination, e.g. a film of oil floating on the bath surface, adhering to the part on the way into the bath.
Mike Halloran
Pembroke Pines, FL, USA
RE: E-Coat Paint
http://
http://www.electrocoat.org/troubleshoot/index.html
With regards to surface defects, if there is a "tiger stripe" appearance, this is likely related to the grinding operation. Grinding can leave a surface that is difficult to clean and obtain good paint adhesion. I would investigate whether or not the parts are taking on a good phosphate coating, specifically in the areas where the stripes appear.
RE: E-Coat Paint
If their description of the process is correct, then it's self-leveling... a non-uniform electric field would do it, but how on Earth would you create one? Once each bit becomes insulated, it's effect on the field should be zero.
Blistering would scream contamination to me, but you said that problem has disappeared... do you know why it disappeared? Maybe they're contaminating it in another way.
Do you have a pic of how these are laid on the racks? That may lead us to better suggestions.
Dan - Owner

http://www.Hi-TecDesigns.com