I need a sensor capable of detecting a 3mm hole punched in a piece of sheet metal, as the sheet metal is moving down a conveyor line. I have access above and below the sheet metal.

any suggestions would be greatly appreciated!

 

If the hole is always in the same position (as a guide for cutting, for example) then use a photocell as detector, and a light source on the opposite side of the metal sheet.

If you need to detect any hole in the sheet, use a battery of detectors covering the whole width of the sheet, with a band of lightsources on the opposite side, or a vision system (DVT or Cognez do great at such applications).

Hope this helps,
Daniel Chartier

 

There are a few things that need to be defined. What type of conveyor is it and does the conveyor belt block access to the hole? Is the hole is a consistent position (withing a millimeter or so) across the conveyor?

Is the hole in a consistant location, an optical through-beam sensor should be able to pick it up. If it is not, then you might need to back light the hole and use a simple vision sensor to detect the light coming through the hole. In either case you probably need another sensor to detect when the part is present (so you know when to look for the hole).

If the belt blocks access to the hole, you'll likely need to add an inspection station into the conveyor.