Calibration and validation
Verification that the detector actually meets the critical limits stated in your HACCP plan — in a form you can put in front of an auditor.
What we do on a calibration visit
- Verify detection against certified test pieces in ferrous, non-ferrous and stainless steel, on your actual products
- Check every product programme, not just the one running on the day
- Verify the reject physically removes the item and that any reject confirmation sensors work
- Check access control, so sensitivity cannot be changed without it being logged
- Inspect seals and glands, because moisture ingress is what quietly destroys detection stability
- Issue a written report you can file and produce on request
What auditors typically ask
How often do you test the detector, and why that frequency?
The frequency has to be set in your HACCP plan and be justifiable. Most food producers test at start-up, at product change, at shift change and at the end of production. What matters is that the frequency was chosen deliberately and is actually followed — not that it is unusually high.
Can you prove the reject actually happened?
This is where many fail. It is not enough that the detector signalled. There has to be verification that the item was removed and ended up in a locked container. We can retrofit reject confirmation sensors to most installations.
What happens to product run since the last passed test?
There has to be a written procedure. If a test fails, everything produced since the last passed test must be identifiable and handled. This is a requirement, not a recommendation.
Are the test pieces traceable?
Test pieces must be marked, and the material and diameter documented. Worn or unmarked spheres are a classic non-conformity. We supply traceable test pieces →
Can sensitivity be changed without a record?
Access to the settings has to be restricted. If an operator can turn the sensitivity down without it being logged, the control point is not under control.
Setting a defensible critical limit
The most common weakness we see is a critical limit copied from a datasheet. An auditor is entitled to ask how the figure was established for your specific product — and a manufacturer's reference figure measured in air is not an answer.
If you need to establish or revise a limit, send the product to our test centre. The test report gives you a documented basis for the number.