I am running a project on trying to find a method of detecting splits that are present in pressed metal along a manufacturing press line.
The system is to be placed into a manufacturing press line of car panels that will automatically detect and notify when a split has occured during production.
Some methods I have come across include the use of light or infra-red and also heard ideas about the use of harmonics.
Does anyone have any methods that they know of? Or more information on the mentioned techniques?

Thank you