Metal Detector Challenge Test Log for Food Production Lines
A metal detector is only a control if you can prove it worked at the time product passed through. This log records the challenge test with certified pieces so there is evidence for every run.
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Metal Detector Challenge Test Log Template
Metal Detector Challenge Test Log
Company: Harvest Line Foods Ltd Line / detector: Line 3 / MD-03 Product: Granola bar 40 g, lot GB-240918 Date: 2026-10-20 Shift: Day Test frequency: Start-up, every 2 hours, after changeover, end of run
Test pieces
Ferrous: 1.5 mm Non-ferrous: 2.0 mm Stainless steel: 2.5 mm Test pieces are passed through the center of the aperture, then the leading edge or the position of lowest sensitivity, inside the product when possible.
Challenge results
| Time | Fe detected | Fe rejected | Non-Fe detected | Non-Fe rejected | SS detected | SS rejected | Fail-safe OK | Initials |
|---|---|---|---|---|---|---|---|---|
| Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | ||
| Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | ||
| Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | ||
| Y / N | Y / N | Y / N | Y / N | Y / N | Y / N | Y / N |
Corrective action
If any test piece is not detected or not rejected, hold all product since the last good test, stop the line, call maintenance and retest at the sensitivity limit before restart.
Product held: ______ Lots affected: ______ Disposition: ______
Review
Test piece sizes, positions and frequency shown are examples. Set them from the detector's validated sensitivity for your product, your HACCP plan critical limit and customer or retailer codes of practice. Calibrate and verify test pieces against their certificates.
Digital line checks
Optional review of capturing line checks in your MES or ERP and linking them to lots.
Optional. The tool and every export work without this. No spam.
How to use the template
Fill in the header fields once, then print or export the document and use the results table at each check. Pass each certified test piece through the detector, ideally in the product pack, at the center and at the position of lowest sensitivity. Record whether the detector alarmed, whether the reject device removed the pack and whether the fail-safe, such as a belt stop or bin-full alarm, worked. Sign and have a reviewer verify at the end of the shift.
- Use certified test pieces and keep their certificates on file
- Test with the actual product setting loaded on the detector
- Retest after any product changeover or maintenance
What good looks like
Sensitivity depends on product effect, pack size and aperture. Wet or salty products create a product effect that reduces sensitivity, so a sensitivity that works for dry crackers may not work for cheese or sauce. Determine the smallest ferrous, non-ferrous and stainless pieces you can reliably detect for each product and use those as challenge sizes. Stainless is hardest to detect, so a stainless pass is the strongest evidence.
Corrective action and traceability
If a test fails, product made since the last good check is at risk. Hold it, re-run it through a working detector, then record disposition. Link the log to the lot or production order so a lot release or a customer complaint investigation can pull the evidence quickly. Many plants store the result in the MES and keep the signed paper as a backup.
Common mistakes
Testing only ferrous pieces, passing the piece only through the center, testing with an empty pack instead of product, never testing the reject mechanism, and filling in the log in one batch at the end of the shift. Also avoid using damaged or uncertified test pieces.
Frequently Asked Questions
How often should a metal detector be tested?
At start-up, at regular intervals during the run, at changeover and at end of run is common. Your HACCP plan, customer code or retailer standard may set the exact frequency, so follow the strictest that applies.
Why test non-ferrous and stainless pieces?
Ferrous metal is easiest to detect. Non-ferrous metals such as aluminum and brass, and stainless steel, are harder, so testing them shows true sensitivity for the contaminants that could occur.
What is a fail-safe test?
A check that the detector reacts safely to a fault, for example stopping the conveyor or alarming when the reject bin is full or the air supply drops. Record it with the challenge test.
Is metal detection a CCP?
It depends on your hazard analysis. Some plants treat it as a CCP, others as a prerequisite or operational control. Decide with your HACCP team and document the rationale.
Netray can help capture test results in your MES or ERP and tie them to the lot. The template works without any contact.
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