Metal detectors and X-ray systems are the last line of defence before contaminated product leaves the building, sitting directly on a critical control point in the HACCP plan. Most audit findings against them don't come from the detector missing something on the line, they come from the paperwork behind it. A large share of BRCGS major non-conformances on detection equipment trace back to monitoring records, not the equipment itself failing. A CMMS like OxMaint keeps sensitivity tests, calibration and maintenance evidence linked to every unit automatically.
Close the Gap Between Testing and Records
Sensitivity checks, calibration certificates and maintenance history tracked against every detector and X-ray unit on your lines.
Metal Detector or X-Ray: Different Tools, Different Checks
The two technologies catch different contaminants and are maintained in different ways. Metal detectors are typically verified against certified test pieces rather than formally calibrated, while X-ray systems involve more formal calibration covering generator output and beam alignment.
| Aspect | Metal Detector | X-Ray System |
|---|---|---|
| Detects | Ferrous, non-ferrous and stainless steel | Metal, glass, stone, bone and dense plastics |
| Checked using | Certified reference test wands or test pieces | Calibration standards for image and generator output |
| Key maintenance point | Coil, aperture and rejection mechanism condition | Generator function, collimator alignment and detector gain |
What Changes Sensitivity Without Anyone Noticing
Belt Speed Drift
A slower or faster belt changes how long a contaminant sits inside the detection zone.
Recipe Changes
Shifts in moisture or salt content alter the product signal and can mask a real contaminant.
Electromagnetic Interference
New motors or wiring installed nearby can quietly degrade a metal detector's sensitivity.
Window Contamination
Residue on an X-ray viewing window reduces image contrast without an obvious alarm.
Building a Detection Equipment Maintenance Routine
Verify at Every Changeover
Re-check sensitivity whenever the product changes, since product effect shifts with the recipe.
Track False Reject Trends
A sudden spike in false rejects usually signals drift long before a real miss would occur.
Re-Validate After Any Change
Any mechanical or configuration change needs full sensitivity re-validation, not a quick check.
Link Records to the Unit
Keep calibration certificates and service history attached to the specific detector or unit.
Detection Equipment Maintenance Maturity
Running, Not Verified
The detector is switched on and rejecting product, but nobody has confirmed sensitivity recently.
Tested but Scattered
Tests happen on schedule, but records sit in separate folders, hard to match to a specific unit.
Linked and Traceable
Every test, calibration and repair sits against its unit's history, retrievable in seconds.
The Records Fail Before the Equipment Does
A wrong-size test piece that happens to pass, a calibration certificate filed against the wrong detector, an annual service that was never linked to the unit that received it, these are the findings that turn up most often at audit, not a detector that genuinely stopped working. Keeping monitoring and calibration evidence tied to the exact piece of equipment is often the difference between a clean report and a major non-conformance. Sign up free to link every test and service record to its detector, or book a demo to see CCP monitoring tracked end to end.
Never Search for a Calibration Record Again
Every sensitivity test, calibration certificate and repair tied directly to the unit that received it.
Frequently Asked Questions
Do metal detectors need annual calibration under BRCGS?
BRCGS does not mandate a fixed annual calibration for metal detectors, so facilities should follow the manufacturer's recommendations while still documenting routine verification against certified test pieces.
Why does belt speed matter for detection accuracy?
Belt speed determines how long a contaminant spends inside the detection aperture, so any deviation from the validated speed can cause the system to miss contaminants at the minimum detectable size.
When does a system need full re-validation rather than a quick check?
Any mechanical change to the detection head or aperture, or any change to operating frequency or configuration, requires a full re-validation of sensitivity for every affected product code.
What causes X-ray image quality to degrade?
A drop in image sharpness or contrast often points to X-ray tube output decline, detector gain drift or generator kV drift, all of which need calibration correction.
What should a metal detector validation report include?
A complete report should cover equipment details, product list, sensitivity targets, test piece IDs, detailed pass or fail results, corrective actions, calibration certificates and sign-off by responsible QA personnel.
