Heat source for oven.

[Guest]

Found this http://www.pfonline.com/articles/99sum02.html . Pretty cool read, but pmt of 360 deg. in 4 minutes. my oven won't get that hot that fast much less the parts in it!I'm also now confused as to the thermodynamics of being able to heat a part that quickly all the way through without seriously over heating the coating on the surface first.I know they're expensive but would an infrared heat source for my yet to be finished big oven be more efficient or effective?

[rbroker]

Re: Heat source for oven.

Wouldn't positive pressure in the oven make parts heat faster? Like a pressure cooker.

[Guest]

Re: Heat source for oven.

My question was based on the coating process not the casting. Sorry for the confusion.I was wondering what broker was refering to. pressure cooking just allows you to super heat by not letting the air or steam to escape effectively disipating heat.So you're right broker,if you are able to circulate the same air and keep heating it,it will get your oven temp up faster. I did find some info on that same site that explained infrared heating. Sadly most of it was immediately familiar as I learned all of that in school so many years ago.I'm still curious, if they're able to bring the temp up that quickly does it bypass the flowout time or significantly shorten it? This seems like it would also reduce outgassing depending on the heat source.If I remember right it's short wave IR that heats the coating,medium wave passes through the coating and heats the surface of the part,and long wave heats throughout the part.All this just adds to my questions about the best heat source for my oven.Anybody using anything besides the standard gas or electric elements?

[benwish]

Re: Heat source for oven.

... pressure cooking just allows you to super heat by not letting the air or steam to escape effectively disipating heat....

This is not correct.
>
Pressure cooking is a method of cooking in a sealed vessel that does not permit air or liquids to escape below a preset pressure. Because the boiling point of water increases as the pressure increases, the pressure built up inside the cooker allows the liquid in the pot to rise to a higher temperature before boiling.
...
Foods are cooked much faster by pressure cooking than by other methods, and with much less water than boiling, so dishes can be ready sooner. Less energy is required than when boiling, steaming or oven cooking. Since less water is necessary, the foods come to cooking temperature faster.
>

Boiling point and energy savings are the key words.

The powder doesn't care where the energy it needs to cure comes from.
You need a certain temp to start the reaction, a certain time at a certain temp to flow out (liquid phase) and a certain time to fully cure.

IR elements (gas or electric) boost just the energy input into the whole system. The object is getting faster to reaction temp and the powder will gain from this. You will save at the very end some kHh's.
The effect on the powder is small compared to the rapid heat up of the steel. However, dark colors absorb more radiant heat then e.g whites, in other words, you might run into color changes.

The problem is, you can't really control the IR elements. They fire or they are cold. This makes it an unstable temperature profile and most powders don't like that. If you just make 2 dimensional panels you can calculate the thermal effects. If you are going for any kind of 3-dimensional objects this calculation gets realy difficult. IR heating is not as easy as the manufactors make it sound.

B

[Guest]

Re: Heat source for oven.

Not sure why my admittedly simplified explanation of pressure cooking was wrong.Any way controlling the temps being a problem was my thought as well that's why I was wondering if anyone was using something besides the standard heat source. If so my next questions would have been about the design and efficiency.