Stranded vs. Solid

my question is, "why not use a non-contact temp sensor"?

Hello Fredski;

That is not a practical approach to this particular issue, the sensors would be hit, cut, burnt and ruined in no time, lots of heavy objects moving too close, hammering etc. But thanks I appreciate it.

I'm thinking no. you have several feet of clearance

That is an intersting concept, I might be able to locate them all in a protected cabinet and have them focused at the corresponding points.

But I'd need them to have a presetable output (different temperatures for each model) and if they are available, I'm afraid they won't be cheap at all, besides you'll have to set one by one, instead of just touching the model selection on a screen.

Thank you

you're a smart guy, you could set up 3-5 guns that could give an instant read on exact points with a single push of a button or even in software

I have a TherMonitor that measures up to 2K degrees F. The major advantage is it has an analog output that i can connect to a recording O Scope and record the temp over time.

Used it in many applications.

a non contact would be better,..... also they make thermo pencils to that change color when you reach a certain temperature I know they have them for preheating material....... these are probably the best and most cost effective..

I like them too, but there are some restraints in this project: The mounting of the sensors would be subject to a REAL harsh evironment and frequent position changes, the available area is no more than 24" by 24" with most of the area occupied by the fixture and workpiece, and I'd need 8 of them. Too crowded for the operator to do his job.

Besides, I already invested in the control and wrote the program, I'm using a 8 chanel K T/C input module, which, alone costs 1900.00 USD.

In the way I'm doing it, everything is invisible to the operator, is hidden below the fixture; the purpose is to retain the work piece 'till all welds are done, or have the supervisor release it with his key.

I would look for unsheathed T/Cs, which can be quite small, and solder or braze like-to-like to stranded extension wires.

That sounds good, very simple solution, somehow I got stuck to this either solid OR stranded dilema, but this combination should definitely make it !

Thanks a lot Tornado GA

Thermocouple output is on mV scale plus is of high impedance, and welding current that close will make it next to unreadable, unless you make special arrangements. (Optoisolate everything and pray real hard). Another problem is with TC extensions. Every connection is no less than a new thermocouple in series, which MUST be canceled out (not easy, becouse that connection temp must be controlled) S.M.

Wouldnt thermal imaging work for this? Several cameras could watch the weld from all sides and respond to the data via a robotic welder.

I think something like this....

http://www.omega.com/pptst/OS210-C4.html

This is probably your best option, the hand held ones not so much, great for walking a building and shooting HVAC registers but the beam with (spread ratio of the beam) is to great and this one that Solar Eagle has provided with the 30:1 possibility will allow you to pinpoint the transmitter / receiver for a more accurate reading of the surface of the weld.

Yes Solar Eagle..."like this". The model you picked up on is good up to 500°C.

Type 'k' t/c's are generally for high temp application (up to 1250°C)

Experiment. Will only take an hour or three -

P.S. Most reply posts are guesses. Half of the others are wrong. But which half? Half of mine is wrong! Experiment - then you will KNOW!

Half of mine is wrong!

Since you didn't offer anything actually, does this mean that only a quarter of the others are wrong ?

non-contact is still the only correct answer

No, three quarters.

Well now...if you say so... I believe you, but the majority won't.

They're wrong, too.

Type K wire is probably available in 16-18 gauge. You'll liklely have to weld, rather than braze the junction (don't know what your seam-weld temperature is, but you don't want the t/c junction coming apart).

Also, 16-18 gauge wire is probably thin and flexible enough to run directly to your monitoring equipt.

Not sure of you process....but a 100% penetration weld will most likely weld your thermocouple 'shoe' to the bottom of the seam. Process controls on systems I've built rely on visual, ultrasound, x-ray for examination. A 'shoe' I've had success with in electroslag and mig fill is a copper block which conducts the heat and does not bond...that might hold thermocouples and slide along the back side. Good Luck!

Hello Gerald:

I've never built something like this, but bonding was one of my concerns, I will definitely give copper a try.

Thank you

You can get a K thermocouple in a bolt on. The junction of the thermocouple is in the crimp socket of a ring terminal. Just bolt the the ring terminal to pads that you are going to use.

Great ! I hope they make them in less than a quarter inch diameter.

Thanks Ozzb

NML-2.gif This is what I had in mind-not a great way to detect breast cancer but might be a great way to monitor a weld

Hi,

I couldn't open your link, but breast cancer is not a concern, as I volunteer to manually do mamograms on willing ladies every once on a while.

I like the way you think Iris. Good, old school, back to basics, GA.

I like your reference to the law of intermediate metals.

Some that post here should read up on that.

I'm sure that GlobalSpec could point to many good vendors that have all that the OP needs.

Also, here's one of many online temperature guides:

https://www.omega.com/temperature/Z/zsection.asp

However, in this case, (as I understand it), I would have to agree with Fredski. The best way to go is non-contact, (IR). Not handheld, but with a remote sensor, and possibly even wireless.