The majority of industrial metal detectors are balanced coil systems. Three coils are wound onto a non-metallic frame and each coil is exactly parallel with the other two. We explain exactly how metal detectors operate in our Metal Detection Guide. You can read more about this from page 8 of the guide.

Related Content:

• Metal Detection Guide

The sensitivity of an industrial metal detector can vary depending on the application, the equipment manufacturer, and the metal detection system itself. Sensitivity performance is determined by the diameter of a sphere made from a specific type of metal. The sphere must be reliably detectable when placed in the center of the aperture of a tunnel metal detector. A tunnel metal detection system loses sensitivity the larger the aperture size.

Dry products such as confectionery and cereals, are relatively easy to inspect. Detectors operating at high and ultra-high tuned frequencies (typically in the region of 800kHz and above) deliver high levels of overall sensitivity and are especially good at detecting stainless steel type contaminants.

When inspecting wet or conductive products, including inspecting products in the food industry such as fresh meat, poultry, cheese, fish and metallized film packed products, the situation is different. The wet product itself creates a 'product effect signal' in the detector – and this signal needs to be cancelled out before inspection can begin. Innovative multi-simultaneous frequency technology combined with a product signal suppression algorithm can be used to overcome product effect, detecting significantly smaller metal contaminants.