52043

We want to switch to infrared curing on powder coating  

April 30, 2009

Dear reader,

Here at our industry we use convection ovens for curing the powder coating on our products, however we are growing short of space and the time needed for curing the paint is too high (about 20 min) so we are considering using infrared lamps to cure our products, since my ovens today are about 6 m X 3 m X 3 m (1 meter is about 3,3 feet) and the curing temperature that my paint requires range from 170 deg C to 220 deg C (338 deg F to 428 deg F) i would like to have an idea of how many lamps, and what wattage these lamps must have so that i can substitute my convection ovens for IR ones.
Bear in mind that the parts that i usually cure range from 0,2 m X 0,2 m to 1 m X 1 m (although they are not necessarily flat, instead, they have a wide variety of geometry)

Giulianno Sperotto
Methods and processes analyst - Fortaleza, Ceará, Brazil

I am not going to give you the answers you require... only some good advice. Without visiting your premises no one can/should give you advice on the locating of the heat source, their number or energy required. As you state the geometry of the items makes it an almost impossible task. In the long term you will save money by obtaining the advice from a company who can visit you and see what problems need to be overcome, i.e. shaded areas etc.

Terry Hickling Martex Paints Ltd    Birmingham, UK

I do understand why you can't give a response to the letter (reading it now, seems I gave to much information, and the tone seems to ask for a precise response...), though my actual interest is in obtaining some ESTIMATES from people who already use IR ovens. The person who is providing a consultant job for us, is also a representative of the company who wishes to sell the quartz lamps for us, so i'm just trying to check what he is telling us.
For example, when asked why would a near IR emitter wouldn't be in our interest (since it provides the faster cures) he couldn't clearly state why (he seems to just want to sell medium IR equipment for everything), though i did later found out that near IR emitters suffers interference from paint color (white absorbing less energy, black absorbing more) while medium and far IR do not (we use a wide variety of colors).
so if you could say what your impression on comparing IR ovens to convection ones, or estimates you have for IR ovens that would be much appreciated.

Giulianno Sperotto
- Fortaleza, Ceará, Brazil

PM's are more involved(time/cost)with IR's. Make sure and ask the rep to explain preventative maintenance procedures with you because it takes a greater commitment to operate an IR. Powder blows off of the parts onto the reflective surface and then cures. They need to be chemically stripped and polished frequently to keep the IR functioning at full potential. The way that you find out the the reflective surfaces are dirty is when a whole days worth of parts come out under-cured.

Sheldon Taylor    supply chain electronics Wake Forest, No. Carolina

Hi, tried to contact you direct via your email address and fax number without success. If you require assistace please contact me direct.

Terry Hickling Martex Paints Ltd    Birmingham, UK

That's strange, as for fax maybe it was required that you called and asked for fax signal first, or maybe one of the huge number required to make an international call was missed... anyway, I'll contact you, hope you can get back to me.
And thanks for the heads up Sheldon, I'll look into that, but i think that just applies to IR lamps right? or does it apply to ceramic surfaces as well?

Giulianno Sperotto
- Fortaleza, Ceará, Brazil

There are different designs so I can't really say unless I can see how the ceramic is being use. My main point was just check into the PM process of the unit that you buy. The IR that I used to use had removable reflective surfaces behind the (bulbs?/elements?) and it took everyone by surprise at the amount of effort involved in keeping the oven at peak performance.

Sheldon Taylor    supply chain electronics Wake Forest, No. Carolina