Recurring Powder Defect

You say that there are brackets welded to the back of the panel.  Do the wrinkles appear behind the brackets?

Looking at the photos, you say that the blemish occurs above a certain line.  Are you certain that there is nothing in your oven that could be disturbing the powder?  Or even something between your painting area to the oven?  Is your oven a batch oven or continuous?  What type of heat source?

Good morning. That is a fun problem you have there. It is always the unknown that takes the fun out this isnt it.

I have a couple of questions:

1. Please give me the steps in MFG. Are these parts handled by 1 or more operators as they are being punched, cut, welded?

2. What is your pretreatment method? Batch, Automated, 3 stage, 5 stage, spraywand?

3. Are there any silicones in your plant? WD-40 etc?

I worked with a company in the Charlotte area that had similar problems, we narrowed it down to 1 of 4 of the metal workers in the plant that was sneaking WD-40 onto is work station because it was his preference in lubrication chemistry. It was disasterous. The problem was not quite as bad as what we see with yours in the photos, however, the parts failed quickly in use from UV and weatherability.

Let me know about this. We might also be able to send someone in to help you. I am not so convinced that this problem is cure related as it would be more predominent throughout the part. I am thinking there is something there.

Even if properly cleaned, if there is a history of a silicone contaminent, it will show itself with adverse properties following cure.

Good luck here. I will look for your response.

Travis

With a strange problem like this, it is often helpful to break the steps down (just like you have) and go through them with a fine-toothed comb.  I agree with Travis that this is probably not a cure related item, per se.  What I mean is that it is probably not related to temperature or time.  Let's create a simple test procedure and see what happens:

1) Isolate the cleaning process by cleaning the heck out of the part.  Go over the part 2 or 3 or 4 or 5 times instead of the normal process.  Make sure you are using good spray wand practices by cleaning it starting at the top and working your way down.  Rinse the part several times and watch for water breaks.  Apply the seal the same way.  It can also help if there is a supervisor or, better yet, a manager present to oversee this.  Employees have a tendency to do things differently when "nobody's looking", right Travis.  By the way, Travis, you have a great story that illustrates this point perfectly, but in regards to applying the powder itself.

Process the parts as normal.  If the parts come out good, then your problem was in cleaning.  If the parts come out bad, move on to the next part of the process.

2) Try running only 1 part at a time in the oven.  This can help isolate the air currents and a few other intangibles related to the oven.  Try orienting the parts differently.  Try a rack with all of the parts front-to-back.  Try another rack with the parts front-to-front and back-to-back.  Space the parts out further. 

3) Try making a panel without the brackets.  Or change some other part of the manufacturing process.  Compare the exact process used by these problematic parts with the ones that come out fine every time.  The environment can sometimes affect the quality of the finished part.  Are you always running the larger parts at the same time of the day?  Try mixing it up.