# Hole Detection in Steel

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#### Burda, Jason M.

Looking for any good sources as a place to start for find sensors, equipment, suppliers for hole detection for cold rolled stainless steel.

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#### Anthony Kerstens

I've used ordinary thru-beam photo sensors
in the past. Use a PE with a relay contact,
and put an array in series. You may have to
stagger the array depending on the sensing
diameter and the hole you need to detect.

Alternately, Sunx has a sensor with a six inch
long sensing area to detect down to 1/8 inch. These have frequency settings so they could be placed end to end without problem.

I've also seen some (old) home-made attempts with
four foot light fixtures and a PE array, but the
light source often was damaged by the leading steel edge.

Anthony Kerstens P.Eng.

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#### Randy DeMars

You might try a light curtain, if you are willing to spend that kind of \$.

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#### Burda, Jason M.

Thanks for the info. Does Sunx have a web-site that you know of, I'd like to contact them, the only problem I see is that I need to cover an area 62" wide and the width of the product varies down to 28". Of course, the level 2 system knows when a width change is going to occur.

Sounds like a really good idea though, especially the part about the different frequencies, this would allow you to detect in which zone the hole
were seen. Just out of curiosity, what was the thickness of the product you used? I am looking at detecting holes down to 1/8" in material that is up to .3" thick.

Thanks a lot.

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#### Steve Preslin

There is Harris Instruments that make a line of products called ScanLine, try an intertnet search they shouldn't be hard to find. It's exactly what you are looking for.

Regards,

Steve

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#### Curt Wuollet

Depending on speed, any machine vision setup
with a light source behind the product should work. You could have a long working distance to get around dirt and curl problems.

Regards

cww

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#### Tony Firth

Remember, many years ago, (>25), product made by Binks, (Spray Paint Equipment Manufacturer), - "Pin Hole Detector".

Consisted of 3 fluorescent tubes above sheet steel, (One on each phase pair of a 3 phase supply so that light would be continuous - and also seem to remember that supply was at 400Hz), and a fiber optic bar bundle beneath sheet feeding
photo detector arrays for holes in any of five zones across sheet. Was capable of detecting holes down to a few mils in dia at a fairly high speed sheet speed. (But don't remember specs). When hole detected, paint spray nozzle marked edge
of sheet with color corresponding to the zone hole was found in. Suggest checking with Binks, they may still be in that business.

Tony Firth, Electrical Eng.,
Quester Technology Inc., Fremont,CA