Searching for Non-Contact Temperature Sensor 24vdc or 120vac

Good afternoon, I have an application where we induction harden different areas on our assembly part using coils that wrap around and heat up to high temperature, then quench to harden.

Issue: When the coils wrap around the part, the ends of the coil make contact and, to oversimplify, heats up the part. Sometimes the ends of the coil do not touch or are worn out, so the coil closes over the part, the PLC fires the output to heat, the machine thinks it heated the part (but it did not), and lets the part go for the robot to grab.

I am in search of a 24 VDC or 120 VAC non-contact infrared thermometer I can use to shine this on the coil 24/7 so I can know if the coil heated up or not. Anyone recommend any they have used? This machine runs 24 hrs 5-6 days a week, but the sensor will be on 24/7 as we don't power this machine down over the weekend.

Thanks,

I have used Keyence FT Infrared sensors with germanium lense and rugged purge air box.

https://www.keyence.com/products/process/temperature/ft/

This was in a very bad and unforgiving environment and the sensor held up well. They cost $$, but Keyence has usually been pretty good in my experience.

Have a look at the Raytek line. I have used them for a variety of different applications and have always found their tech/application support to be outstanding.

Thanks for the info. One question, I noticed on many data sheets, it says this for example:

"12 to 24 VDC (≤2.5% ripple) @ 20 mA"

What does the ripple mean? Is that saying the voltage will vary from 24VDC ± 2.5% ?

Thanks,

when converting an ac voltage to dc, electronics are involved in the conversion. in simple terms, a rectifier bridge is used to convert the ac sine wave and then filter capacitors are used to flatten out the converted sine wave to dc. unfortunately, this process is not 100% effective and what you end up with is a dc signal that looks like a bunch of ramps, then drop offs that ramp up again to the same level and repeats. this is called ripple.

dc power supplies come in two types, switching and linear power supplies. look at the specs for the power supply you want to use and see what the ripple factor or % ripple is and that should help you in your search. I have used these power supplies, ab, sola, automation direct, and I know that there are others. do not take the word of any salesman who recommends their power supply, look at the specs and confirm that what they say is true.
james

If you are using a PLC that has a thermocouple input card available I suggest infrared thermocouples. I usually use T type and find them reliable.

I have worked on a machine that had an Omega infrared sensor to monitor the surface glass temperature. It was either 10 or 24VDC power with a 4-20mA output. I am sure Omega has more options.

@James Mcquade Thanks for the info man. So the "12 to 24 VDC (≤2.5% ripple) @ 20 mA" I pulled from a data sheet for a infrared thermometer, so does this mean that the supply going into the thermometer must have a ripple less than 2.5%? So I have to check my own power supply and make sure the ripple is < 2.5%? What happens if the ripple is higher? That would just make the sensor not work as good or fry it?

@I_Automation Thanks for the recommendation, we are just using binary to pass or fail it in the PLC. I'll program the sensor to the min. temperature level it needs to see for it to pass.

Another approach that can be used for this type of application is to monitor the power draw of the induction machine. A properly heated part will have a different power draw signature than a part that didn't get heated. You can see this even at the power feed (480V 3phase, I'm guessing), so you can avoid all the complications with measuring power on the coil side.



This approach can be useful in cases where it's hard to get a line of sight to the part, or where the sensor has trouble staying clean. Depending on the level of sophistication needed, even a simple amp switch clamped on one leg of the machine might do the trick. It would answer the question "Did I pull > X amps for that heat cycle or not?" Some testing with a handheld amp-clamp would get you an idea if this approach would be viable.

@Brian123 Yeah, I was looking at that option as well, the one I found required analog signals, and we don't have a card on the plc for that, so I was looking at this option. I think Keyence has a couple good ones from what I saw.

If you don't have an analog input and just want a signal do similar to what I did for a hot laminator monitoring the output product.

I put an infrared thermocouple connected to a small, cheap Automation Direct temperature controller. For my use I had a photoeye sense the part, start a timer so I wasn't looking at the first inch and give the thermocouple time to settle its reading, then turn on the power to the temperature controller output.

The temp control was set to heat mode and if the timer came on and it was calling for heat then the product was cold and set off an alarm.

The fun part:
When I installed it I put a temporary label on it saying "Yo**** Is Running Cold Panels Alert" (named after the operator that caused it to be installed) and for a week he was proud of it - until someone told him that it was really an insult that he wasn't doing his job and he pulled the label off.

alive15 said:

@Brian123 Yeah, I was looking at that option as well, the one I found required analog signals, and we don't have a card on the plc for that, so I was looking at this option. I think Keyence has a couple good ones from what I saw.

Click to expand...

If you have room in the panel, something like this would be able to convert the analog signal to a digital one. It would let you use any temp/amp sensor you wanted.

it's been a while since I had to deal with ripple, so here goes. ripple creates noise to the power leads and may effect the way the sensor operates and sensors output.

you might look for an analog sensor that has a ct configuration (microswitch for example). you wire the sensor and place the power lead in line with the sensor core for an output. you can monitor the current and also monitor the current fox the specified time in the plc to make sure the connection doesn't get lost. I know that there are several brands out there.
james

You can try Land or Willamsons Pyrometers

@I_Automation Haha, that's hilarious bro, thanks for sharing

@Brian123 That device seems really useful, I think I will buy this and use the setpoint feature on it, along with a cheaper thermometer. This is probably cheaper than buying the Keyence version.

@James Mcquade Thanks for the info man, I'm gonna read more about this later, it's oddly appealing to me.

@bornwild I will check them out also, thanks.