Glossary · Packaging and intralogistics
Metal detector
Also known as: Metal detection system, Inline metal detector
German: Metalldetektor
In food, pharmaceutical and packaging lines, a metal detector is an inspection device that detects ferrous, non-ferrous and stainless steel contaminants in products passing through its aperture and triggers their rejection.
- Intralogistics
In one sentence
A metal detector inspects products on a line for metal contaminants such as ferrous, non-ferrous or stainless steel and triggers rejection.
Example
Every pack of frozen vegetables passes the metal detector; a test pack with a 2.0 mm stainless steel sphere is run at each shift start.
How it applies
- Engineering: Balanced-coil detectors sense changes in an electromagnetic field. Sensitivity depends on aperture size, product effect (moisture, salt), metal type and position. Stainless steel is typically the hardest to detect.
- Quality: Metal detection is often a critical control point in a food safety plan. Reject confirmation, a locked reject bin and failsafe behavior (reject on fault) are common requirements from retailers and food safety schemes.
- Operation: Regular tests with certified test pieces confirm that detection and rejection work. Failed tests trigger re-inspection of product made since the last good test.
- Documentation: State test piece sizes, test frequency, the response to a failed test and who may change sensitivity settings. Test records must be complete and traceable.
Metal detector vs. X-ray inspection
X-ray systems detect dense contaminants such as glass, stone and bone as well as metal, and can check fill levels. Metal detectors detect metal only, but are often more sensitive to some metals in certain products.