About Needle Detector

Structure of Needle Detector

A needle detector is a device that detects magnetic substances (objects that react to magnets) that react to magnetic field lines emitted by magnets by arranging permanent magnets and detection coils in the upper and lower sensor heads.

検出の仕組み

Magnetic lines of force are formed between the permanent magnet and the detection coil in the sensor head.

When a magnetic material such as a broken needle approaches the magnetic field lines, the field lines are deformed. The disturbance is converted into a current value and detected by the detection coil.

The value is converted to a current value, which is detected by the detection coil.

If the value is higher than the sensitivity setting of the needle detector, the conveyor belt stops, rotates in reverse, and sounds an alarm.

Non-magnetic reactions

As mentioned above, basically anything that reacts to magnets can be detected, but in some cases, even nonmagnetic (non-reactive to magnets) materials can be detected.
Nylon-based products such as stockings (petroleum products) and natural animal leather fall into this category.
In some cases, even accessories that are compatible with the needle detector (NC-compatible products) may be detected if they overlap in number or if their surface finish has been cut off, etc. Since even NC-compatible products show a slight reaction, there are cases where detection is made by adding the reaction of the product itself.

FOLLOW US