Oven problem !!!!!

[tavo1765]

I have 2 ovens at my PC shop.

1. A small 18x18x18, frist curing oven and I still use it if the parts can fit.

2. 8x6x6 electric oven, I only use it when coating larger parts.

Now for my problem.

My smaller oven works excellent all the time. I place large items that use all its space and also fill it with a ton of smaller items, my temps range from 350-450f. All the parts cured in this small oven come out smooth like glass.

Now when starting up my larger oven it takes up to about 30hr to get to about 375f/ or 386 which is about 400f in my oven.

If I take smaller parts which could of been placed into the small one the pieces come out fine, if I were to place a larger items in it and cure they come out more orange peeled. Every larger item comes out not as smooth as the little oven when used which is sad because the small oven cost 300.00 and the large oven was 11,000.00

I was told that I am not letting it heat set long enough before I place parts in it. Also was told that the oven temp is off which it is not or maybe the parts are getting to temp too fast and there is not enough time for the flow out of the powder.

I am very confused at this point because the temps are not off and why do the little parts come out perfect if the oven was heat soaked??

[Popeye]

You might try letting your oven get to temp before you put the part in.. then once you put the part in let it come back up to temp and then start timing.
That's how I do it in mine...
Hope that helps

[KeithLambert7]

Originally Posted by tavo1765

2. 8x6x6 electric oven, I only use it when coating larger parts.

Now for my problem.

My smaller oven works excellent all the time. I place large items that use all its space and also fill it with a ton of smaller items, my temps range from 350-450f. All the parts cured in this small oven come out smooth like glass.

Now when starting up my larger oven it takes up to about 30hr to get to about 375f/ or 386 which is about 400f in my oven.

That's a typo (30 Hours) right? You meant 30 mins I hope. My 6x4x4 electric oven heats in about 20 mins, and the results are excellent. I almost always use the oven from cold start. Only because I'm a clutz and always burned myself trying to get things leaded into an already hot oven, never had a problem starting at room temp.

Your oven's curculation fan is operating properly I assume? Is this a new problem, or from day one?

Keith

[tavo1765]

yes, 30 mins.

I tried heat soaking it for 1hr at 375, then placed a aluminum swingarm that was polished with candy red in and it let it sit for 30 mins, the powder flowed out really bad with tight orange peel which would mean not enough powder, but if I placed that same exact swingarm in the smaller oven it would of flowed out with no problems.

The 2 fans are working correctly.

[bzer1]

What was the part temp? Have you tried to profile your oven? When I built my oven, I placed Pieces of metal...all the same size, weight and material in several spots in the oven and used a laser temp probe to check the temp in about 15 points inside the oven. I hung them at different heights and in the corners and was lucky that they were all within a few degrees of each other. You might have some cool spots in your oven. If that is the case you'll need to fix them.

[tavo1765]

thats good advice, I will try that tomorrow.

[KeithLambert7]

TAV1765

You have a PM.

Keith

[PowderVisions]

Different powders flow at different temperatures. Different powder are developed with different flow agent within themselves. Remember that most product specs from powder manufacturers give guidelines on the cure cycle for each specific powder. When they say the temp should be 395 degree, they mean the part should be heated to 395 degree for 15 minutes, not just the air temperature. You would not pass a destructive powder test by simply putting a part in an oven that was not preheated and runing to temp for 15 minutes, not to mention it would not flow out properly. Veins and texturess are reaqlly prone to oven temperatures.