unique1

Topic: HELP - Powder Coating Blowing off in Oven

Please help! I just put in a load of shutters and as soon as i put them into the gas oven the black wrinkle blew OFF! What do i need to do so the powder does not blow off? PLEASE HELP!

Travis Stirewalt

Re: HELP - Powder Coating Blowing off in Oven


WOW! Loaded question (s)!

Ok, first off, I have a ton of questions:

1. what kind of oven is this?
2. how close are you hanging the parts to the blowers or vents?
3. where are the vents/blowers/ductwork located? 

Most often when powder is blowing off of parts in the oven before the gelling occurs, it is happening because the parts are located directly in line with a vent/blower that has a high velocity of air coming out of it.

Can your air be re/channeled or dispersed with the addition or adjusting of duct work?

We will be teaching students just like you about things like oven design, the application various powder coatings, along with many other helpful topics to help you run a more efficient Powder Coating operation during our 2009 Powder Coating Course – Nationwide Tour.  Our next stop is Louisville, KY June 17-18. Sign up today!

Travis Stirewalt, CSI, NASF
Senior Sales Manager, Eastern US
TIGER Drylac USA Powder Coatings
www.tiger-coatings.com

cprendergast

Re: HELP - Powder Coating Blowing off in Oven

Until you diagnose the problem properly you could preheat your parts (to about 150 deg F) prior to coating them in order to gel the powder before you raise it to cure temps.  Be mindful of thickness as heat will increase your film build.

Last edited by cprendergast (06/05/2009 - 04:04 PM)

unique1

Re: HELP - Powder Coating Blowing off in Oven

Travis Stirewalt wrote:

WOW! Loaded question (s)! Ok, first off, I have a ton of questions: 1. what kind of oven is this? 2. how close are you hanging the parts to the blowers or vents? 3. where are the vents/blowers/ductwork located?  Most often when powder is blowing off of parts in the oven before the gelling occurs, it is happening because the parts are located directly in line with a vent/blower that has a high velocity of air coming out of it. Can your air be re/channeled or dispersed with the addition or adjusting of duct work?

We will be teaching students just like you about things like oven design, the application various powder coatings, along with many other helpful topics to help you run a more efficient Powder Coating operation during our 2009 Powder Coating Course – Nationwide Tour.  Our next stop is Louisville, KY June 17-18. Sign up today!

It's a 8x8x10' oven from rapid eng. The vents are located on the left and right side of the entry doors. The shutters were in the center of the two sides of a 4' wide jig. I also noticed that when someone opened the SPRAY booth doors with the fans on the powder would even have a "cloud" of powder coming off. This is where i knew i would have issues. The problen is still NOT resolved. I'm also trying a different type of chemical to see it will help with the sticking of the powder.

hstockman

Re: HELP - Powder Coating Blowing off in Oven

Dear Unique 1

You might consider adding a VFD to your supply fan motor and adding a timer to create a 2 stage batch oven.  The initial stage would run the supply fan at a lower rpm allowing the powder to gel, then switch to normal operation for better air turns and cure uniformity.

Regards,

Herb Stockman

T&G Industrial Equipment

270-997-0397

unique1 wrote:
Travis Stirewalt wrote:

WOW! Loaded question (s)! Ok, first off, I have a ton of questions: 1. what kind of oven is this? 2. how close are you hanging the parts to the blowers or vents? 3. where are the vents/blowers/ductwork located?  Most often when powder is blowing off of parts in the oven before the gelling occurs, it is happening because the parts are located directly in line with a vent/blower that has a high velocity of air coming out of it. Can your air be re/channeled or dispersed with the addition or adjusting of duct work?

We will be teaching students just like you about things like oven design, the application various powder coatings, along with many other helpful topics to help you run a more efficient Powder Coating operation during our 2009 Powder Coating Course – Nationwide Tour.  Our next stop is Louisville, KY June 17-18. Sign up today!

It's a 8x8x10' oven from rapid eng. The vents are located on the left and right side of the entry doors. The shutters were in the center of the two sides of a 4' wide jig. I also noticed that when someone opened the SPRAY booth doors with the fans on the powder would even have a "cloud" of powder coming off. This is where i knew i would have issues. The problen is still NOT resolved. I'm also trying a different type of chemical to see it will help with the sticking of the powder.

coatit

Re: HELP - Powder Coating Blowing off in Oven

Just a couple things to ask first.

Is the oven, process or powder new? I

If you said no to all of the above consider this.

Most of the time if the powder is being removed so easily it could be the fact that it has a very poor electrostatic bond. Test the application equipment output, shoot some other powder with the same gun on the same material and see what the results are.

Are the parts coming out light after the oven? Over coating can cause the same sort of issue. Excess powder blowing off due to too much powder coat being applied or poor ground during coating

If nothing has changed recently in the process and the equipment is working fine on other coated parts I would look at the powder charge/electrostatic bond and/or the application equipment output. Also check with the powder manufacture and make sure there are no special requirements of this powder. Grind size, additives, wrinkle components all may play into this problem



skip

Re: HELP - Powder Coating Blowing off in Oven

Gel the powder coat prior to hitting the powder coated work with the blast from the recirculating fan. Not usually a problem with liquid which may be dating the Rapid Batch oven.

Find a place to dewll in heat till the powder becomes shiny, then cure with impinged hot air.. So maybe a little I.R.?

skip.

Last edited by skip (02/04/2010 - 08:54 PM)

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