Ideas needed on how to measure temperature between 2 parts

[adammil1]

I have a press that squeezes a material between 2 heated platens, in an ideal world I would love to see a thermal image of what is taking place between the press platens. In reality I could likely settle for thermocouples one/inch or so, but that would be a lot of inches at 36x36". Does anyone know any devices, sensor matrix, and or material that may work here? Temperature sensitive films may work, but the real issue is I have a variable temperature process that ramps up/cools down and I would love to get a window into the process greater than the 1 RTD I currently have. Is anyone familiar with something better than just sticking a few thermocouples in there?

Max temp would be 400degF, pressure could be upwards of a 1-2000psi.

Thanks,

Adam

 

[MikeHalloran]

If you could separate the platens quickly enough and far enough, you could take pictures of them with a thermal imaging camera.

Failing that, you could interpose some enamel paper between the platens and the part, separate the platens a little, yank the paper out to the side, and take a thermal image of it. You'd have to automate the process to get any repeatability, of course.



Mike Halloran
Pembroke Pines, FL, USA

 

[IRstuff]

There's also thermally sensitive paper, although it's likely that your upper temperature range might be a bit too high:

http://www.sensorprod.com/thermex.php

http://www.sensorprod.com/thermoscale.php

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[adammil1]

Temperature sensing paper may work, but would be less than ideal, as I would have to open up the press platens in the middle of the operation. Furthermore since they would lock in the highest temperatures I don't think I would have any luck understanding the cooling side.

As far as using a thermal imaging camera with the platens open, this would be one possibility but also less than ideal as there is quite a bit more going on inside the platens with our materials during the heating process. I also suspect that pressure has a large affect on the heat transfer, plus there is also going to be some steam generation in there. So yes, that would get us closer but would be less than ideal.

Interesting thing is I have seen articles that suggest that there is some degree of research taking place on a technology that would work;

http://mit-pbg.mit.edu/Documents/Th...vices_by_Multimaterial_Codrawing_APR_2006.pdf

I just haven't seen any one selling a system that does this. The other option I suppose may be to glue some thermocouples onto something, but it would be nice if someone knows of a novel system out there that I am overlooking.

 

[IRstuff]

Another choice is simulation, backed with some amount of measured correlations.

How this is the "material?" If sufficiently thick, I could imagine using a surrogate with embedded thermistors and the like.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[MikeHalloran]

Next thing I'd try is face the platens with aluminum plates, grooved and pocketed for an array of diode temperature sensors like this:

https://www.openimpulse.com/blog/2012/07/low-cost-diode-temperature-sensor/

Mike Halloran
Pembroke Pines, FL, USA

 

[adammil1]

As a follow up I just got off the phone with these guys,

http://www.4fos.com/

it looks like the carbon fiber composite guys have been dealing with this issue for years. Their website seems to do a poor job at describing what they are capable of but apparently they can measure up to 1000 points of temperature per meter of fiber optic and wrap the thing in a serpentine pattern through out my box, giving me 40Hz sample rate, and accuracy of +/- 1degC. On top of that it sounds like they can also shed light on strain in the box too, so all and all it is pretty neat. It doesn't come cheap but the knowledge we can gain here is pretty significant.