You can replace them after about 4 or 5 cycles..........
Plus.....
You can change your car's oil every day, your tires every week, your
shoes once an hour--- don't ask me how often I change my furnace
filter.......

In my experience thermocouples either are or aren't- thermocouples.
They open up when they go bad- and then that's it. I don't recall seeing
any fluxuation- but then again I stay in the 1-4 degree C per sec temp
rise rate. I don't know what happens if you go outside that range----
I'l have to try a blowtorch sometime.....

Seriously, I've never seen it (drifting) happen. 

Neil Maloney


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, October 02, 2007 1:04 PM
To: [log in to unmask]
Subject: [TN] Thermocouple Longevity?


Hi Everyone!
 
How many reflow profiles do ya'll put the same thermocouples through
before you think about replacing them?
 
I've typically used them until they quit working or the insulation
deteriorates so bad that I don't want to use them anymore. I was told
that was not a good practice. That your typical K thermocouple starts
drifting after only 4 or 5 thermal cycles. I said; "Really?" I didn't
want to debate a whole lot because it was a customer who said this, so I
just agreed and went on.
 
So, do any of you know this to be a fact, and do any of you trash a
thermocouple after only 4 or 5 profiles and replace them with new ones?
 
Kind regards,
 
Steve Gregory

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