ultra sonic sensors for checking thickness

Does anyone know of a sensor out there to check the thickness of plastic with only haveing access to one side.

We have a few panametrics brand ultra sonic sensors that tell you the thickness but I need on that I can send a descrete signal to a plc input as a go no go gauge

Keyence has many options for you.
www.keyence.com

ya my keyence rep was here yesterday and had nothing that would work

I looked at measuring plastic thickness with access to only one side and the only way they seemed to be able to make it work is if there is a metal behind the plastic. You then have two sensors one measures the distance to the metal and the second measures the distance to the surface of the plastic. The two sensors were combined in to one unit. I will have to dig back through some records to see if I can remember who could made the things. The output was analogue rather than digital and they weren't cheap. If you find a cheap method can you post the info here, I could sell a lot of them.

Bryan

Maybe not for you, but just got this, and it looks interesting.
http://www.ifm.com/ifmus/web/pmd_prd_home!redirect_3dsensor.html

Are there any better than ultrasonic ways to measure plastic thickness?

Is this a plastic sheet? I wonder if shooting a visible (for clear plastic) or infrared (for opaque) laser beam at an angle might be a way to do it. There have to be two reflected beams - one from the top surface and one from the bottom; the distance between them would tell the thickness.

If the material is resting on a fixed surface, one laser displacement sensor should be able to give accurate readings.

OP wants a digital sensor that acts as a pass/fail signal to PLC.

Therefore, the sensor would have to be "taught" or adjusted accordingly, and again each time the spec changed.

Also, we do not know what the tolerances are (resolution required), and how much time is allowed to take the measurement...

Paul

Yeah, I don't see why this wouldn't be a simple task for a laser displacement sensor. Of course, more details on the application might answer this...



-Eric

LadderLogic said:

Are there any better than ultrasonic ways to measure plastic thickness?

Click to expand...

If by better, you mean 'more accurate', then, of course. You could go with a Measurex 'transmittion' gauge ('looks through' the sheet), which, depending on the product, would use nuclear (SR90, or KR85), xray, infrared.

Of course, this is the ultimate sensor, with wonderful accuracy.