Metal Detection Testing & Verification

Hi,

I am trying do create some procedures for testing and verification of metal detectors, what is the best test method for gravity feed packaging machines?

I would start by asking your metal detector supplier.  May be a bit late, but were they asked before purchase? This should have been a piece of equipment reviewed by the HACCP team before the order was placed, that would have saved some debating time.  If they haven't already decided on a test method, how werethe limits specified?

Hi,

The detectors we have are really old, we are actually exploring the possibility of swappping out the units for x-ray.. Not to keen on the idea of having to add radio contamination to the contaminant list though....

The HACCP team was not functional at the time these units were installed. Much thanks for the advice I contacted a supplier and after a lenghty discussion learned quite a lot about metal detectors and x-ray units....

We are going to run several tests, with new test pieces, over the next couple of weeks to sort our metal detectors out until we deicide on how to proceed with the x-ray units...

BTW I did not realize x-ray machines have such a varied number of applications outside of detecting foreign matter.... not to mention there is quite a bit of limitation on what can and cannot be detected!

Thanks...

Metal detectors with tubes utilized for product handling can be the most challenging type of metal detector to validate and verify due to the design and the characteristics of the detector itself.

With Balanced Coil metal detectors (the most common type) the absolute center of the detector is the weakest position for detection of contamination. Therefore the center is the ideal location to challenge the detector during validation and verification activities. With a tube running in this area it can make accessing the true center (weakest area) during validation and verification activities.

Some systems are available with "Test Kits" that provide access and retrieval ports to insert the test samples into the product flow, closest to the weakest point, and be retrieved regardless of proper rejection or reject failure.

You could also conduct validation capability study between the center area of the detector and the area closet to the detector surface to determine the equivalent. This would be a series of test to identify sensitivity at the weakest point vs. the most sensitive point providing statistical data that could be utilized to "validate" an alternative testing method.

Any inspection device will have limitation metal detectors, x-ray, magnets, screen and filters. It is important to understand the risks, understand the technology and strategy utilized to reduce the risk and continuously look to improve the process through evaluating rejected product and identifying root case and implementing corrective/preventative action. Oh and of course document everything

Do we need to calibrate metal detector regularly like once a year besides of using metal fragments before and every 30 minutes during operation.

Please advise

Dear All,

Unfortunately it is unclear whether the OP means verification or validation.

test pieces rather suggests the validation of a CCP but it remains speculation only.

@avila muncar - Based on a few previous threads the majority answer is No unless you have reason to disbelieve yr routine test results in which case you should have had it rechecked already.

Or yr auditor validatably demands a certificate.

Or perhaps yr maintenance section has ample funds to spare. :smile:

Rgds / Charles.C

Dear Charles,

Based on BRC auditor's request, we do annual MD verification by external body. Their method is as same as we do internally during MD daily operation (using test specimens of various metal). I think it's a matter of confidence only as we got certificate to be shown to auditor :smile: 

Rgds / Avila