prox sensor for veneer on white belt? ultrasonic?

We need to find the leading edge of 1/8" thick veneer on a shiny solid white belt, and ultrasonic proximity sensors have been recommended. They will be used in a pretty hot, dirty environment. Does anyone have any experience with these proxs (VIRTU VM18) or others in a similiar application to share? Any recommendations of alternate solutions, or specific models & manufactures, specifications and/or known problems with using these versus normal photoeyes?

They apparently are fairly inexpensive compared to the laser photo eyes we use elsewhere where the belt problem doesn't exist.

Thanks in advance if you choose to comment.

Look at SICK foreground or background suppression PE.
I am short on time right now but might have a chance to look into them tomorrow if needed.


Hope this helps,
Bob

Or www.BannerEngineering.com QS18 or QS30 family.

ultrasonic sensors

We Use the S18U ultrasonic sensor for detecting stained wood. (grey colour) The SIC laser didnt work that well. This solved the problem. I originally thought the laser was the way to go. It worked better than regular eyes, but the colour was still a problem. If thru beam eyes are not practical, the ultrsonic is the way to go, colour has no effect.

When you have a target that is 1/8 inch thick, regardless the color, a convergent beam laser will be more reliable and MUCH faster.

I am with Russ on this one the contrast scanners (convergent beam) type have a teach in function to set sensing range. I had an application where I had to detect xmas paper rolls on a white conveyor where we used IFM-Efector on AS-I. I have also used similar models from SICK.

http://www.sick.com/gus/products/product_catalogs/industrial_sensors/en.html

colour

Colour is an issue with all laser, indeed all photo sensing devices. We did not get reliable operation with grey or blue stained wood. If white is the only colour being scanned, the SIC will work but the ultrsonic can also be taught limits and is fast. We have no issues with wood running 1100 FPM, on PLC 5/40s. On faster applications I would not know. I would try both and see if there are any issues.

Thanks for all the great ideas. The wood veneer is light brown, but its the shiny solid belt with no breaks that is giving us fits! Speed and resolution is also important because we're going to track the sheet with encoders after the leading edge is located.

Have you looked at the Tri-tronics
Smarteye.