John,
You may need to recalibrate your IR pyrometer or readjust the
compensation gain (if your IR pyrometer is so equipted). Since the
emissivity of rubber is .86, therefore at this setting you should have a
lower reading (without compensation) but you get a correct reading at
E=1.0 instead.

At M-FLEX, we have been using the Raytek IR pyrometer to measure the
exit temperature on the surface of the photoresist for a while and
readings usually fall within +/- 5 deg.F(reads 212 +/- 5 deg.F on the
rubber roller surface at 212 deg.F setting monitored by built-in
thermocouples) that is acceptable for the dry film lamination process.

One different thing is for our IR pyrometer, rubber's emissivity is .95
instead of .86. I try to measure the rubber roller surface using E=.86
and got a reading of 226 deg.F that is almost identical with your
reading. So I suggest you to check with the IR pyrometer manufacturer to
confirm about the correct emissivity. 

Good luck,

Quyet Phung
[log in to unmask]

>----------
>From: 	John Gully[SMTP:[log in to unmask]]
>Sent: 	Tuesday, September 17, 1996 9:21 AM
>To: 	[log in to unmask]
>Cc: 	[log in to unmask]
>Subject: 	FAB: Emissivity
>
>Address,
>
>We have recently been measuring the exit temperatures of our layers 
>and panels using a IR Temperature Probe.  These temps were in line 
>with current specifications.  We verified the exit temperatures with the 
>built-in thermocoupler and a temperature probe. However, one of our 
>local sources allowed us to use their IR Temp Probe that took into 
>consideration the Emissivity of the material measured, in this case, the 
>rubber lam rollers.  The exit temp was then 25~30 degrees higher than 
>our initial testing.  
>
>How critical is the emissivity and can it be a factor here?  Does 
>anyone else rely on emissivity to read their exit temps?  The 
>recommended emissivity is .86 (20~30 degrees out of spec) but when 
>using 1.0, the required temp was achieved.
>
>Please advise.
>
>John Gulley
>Compuroute Inc.
>
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