How to test an Industrial Metal Detector?
All industrial metal detectors function relatively the same. There are differences in their base performance hence why some cost more then others. But the principles of metal detection are the same. I’ll cover the general principles for testing all metal detectors that can be applied to conveyor metal detection, pipeline metal detectors, gravity feed metal detectors, web metal detectors, lumber metal detectors, pharmaceutical metal detectors and so on.
How does a metal detector work?
You can envision a metal detector as a big radio transmitter and radio receiver all in one. There is a transmitting coil that ‘broadcasts’ at a particular frequency. This frequency is general chosen based on the product that will be inspected. The receiver coil, or radio, picks up the transmitted signal. If you pass a piece of metal through the opening or ‘aperture’ of the metal detector the radio frequency waves are changed in a way that the receiver picks them up. This would be like hearing noise on your AM radio as you drive under a bridge. Here is where basic metal detection happens. The electronics within the control system decides based on various other parameters whether this ‘disturbance’ is a piece of metal. If so, a signal is sent to a reject device and the contaminate is removed.
Now I know this is a very simple overview of how a metal detector works. I’m not about to get in to the theory of metal detection in order to discuss how to test one.
Basic Steps For Testing A Metal Detector
1) Adjust the metal detector to ignore normal product as it passes through the aperture.
2) Insert test sample (typically a small metal sphere) in to the product stream before the metal detector. Try to position so that the sample will pass directly through the middle of the metal detector opening.
3) Allow the automatic reject system to remove the test product. This is as important as testing the metal detector its self. If the rejection system fails the metal detector is rendered useless.
4) Ensure the rejected product is properly removed from the production stream
There you have the simplest overview of how to test a metal detection system for inspecting everything from cookies, bread, chicken, meat, pharmaceuticals to paper and plastics.
Do you have questions on how to test your metal detection system?
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