Conventional System Solution
some manufacturers use is to increase the system pinhole sensitivity until the smaller
area sidewall pinholes can be detected. There are two problems with that approach:
is an undesirable side effect to the customer - increased cost.
Increasing the sensitivity to
levels sufficient to detect sidewall pinholes results in wasteful
rejection of acceptable material. The rejection occurs because thin foils
typically have some pinholes (see About
Pinholes and Fractures). These pinholes may be of acceptable size for
the application and rejection wastes time, material and money.
Sidewall Pinhole detection depends on formed cavity sidewall angle.
steeper the formed cavity wall, the smaller pinhole area presented.
Therefore it is not possible to set the device to detect a certain size
pinhole, since its location in the sidewall strongly influences its apparent
nearly vertical walls or portions of walls, the pinhole virtually disappears
(as seen by conventional systems). In such a case pinhole sensitivity would need to
increase to unobtainable levels.