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NADCAP and thermocouple calibration

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#70277

NADCAP and thermocouple calibration | 7 August, 2013

I was asked how we verify that the thermocouples INSIDE the reflow oven are calibrated. That seems pretty impractical to me.

Has anyone come across this ?

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#70286

NADCAP and thermocouple calibration | 7 August, 2013

You mean you don't pull all of your thermocouples out of the ovens once a year and send them out for calibration? - lol Tough question. You have a calibrated datalogger. (I assume) You have an oven with preset zone temps, each zone controlled by a closed loop circuit with it's own Thermocouple. You can use the Calibrated Datalogger to verify the set points in each zone. I would think, however, that the above steps must be part of your normal process, documented, monitored, and controlled at that. Good Luck with your NADCAP audit! 'hege

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#70287

NADCAP and thermocouple calibration | 7 August, 2013

And to my knowledge, there is no calibration of Thermocouples. They can only be checked for their continuity and resistive value.

The question would appear to be invalid.

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#70309

NADCAP and thermocouple calibration | 8 August, 2013

Hege, there is no actual calibration of the thermocouple itself. You can however verify that they read correctly. Heller sells an option on their reflow ovens specifically for this purpose.

I hoping that someone chimes in here that is NADCAP certified.

Here is the exact text from the audit form:

Is there evidence that the preventive maintenance is complete, including thermocouple calibration, periodic cleaning of equipment and tools and if used air knife nozzle?

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#70319

NADCAP and thermocouple calibration | 8 August, 2013

I too am hoping a NADCAP guy might jump in here. I would like to know how this portion of the question is handled.

Evidence of PM, periodic cleaning of EQ and tools, no issues. Thermocouple calibration? You would think that evidence of Oven CAL or Oven Verification using a calibrated datalogger would suffice, but it doesn't, not to the letter of the question you have presented, anyhow.

Hey NADCAPpers, chime in!

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