detecting cracks in stamped auto body panels

[valiot]

I'm trying to determine if using an infrared camera will be suitable in my application. Car Body panels come off a sheet metal press. I want to detect splits and cracks in the parts. Before I ask a sales rep to do an infrared test on the parts, I want to know if i'm totally crazy for thinking infrared.

The pressing process causes friction on the sheet metal so I think it will glow. If there are holes or cracks (gaps) in the metal then they should show up as dark black areas right?

I also read about an application called Thermosonix which is ultrasonic vibration of a part to cause heat friction. This might bring out cracks more.

My original feeling was to pass the part through a dark area and shine a light underneath it. This way I could use a regular camera and look for light shining through (yes, the cracks are that big). My only concern is light bleeding.

Any ideas?

 

[IRstuff]

If you are getting through-thickness cracks in your process, you have a problem that should be caught further upstream. Either your press or process is configured incorrectly for the task, or you have substandard material. The material problems should and must be caught closer to the source of the problem.

Every step further downstream before a problem is caught is usually something like a factor in 10 of additional cost hit, e.g., to reject incoming stock as defective is much cheaper than to scrap a completed panel.

TTFN

 

[IRJohn]

A great deal of work has been done on this, although not much has been published. In short, passive thermal imaging (i.e. looking at the part as it comes out of the press) is NOT very successful. Some great work has been done with ultrasonic excitation, but nothing, to date, has been done on a line for mass checking of parts. I don't want to discourage you, and I'd suggest working with more proven applications if possible.


If I can be of further assistance, please feel free to contact me.
John Snell
Snell Infrared

http://www.snellinfrared.com