False Positives

NEEDLE DETECTOR

Since the needle detector detects slight disturbances in the magnetic field lines emitted from the permanent magnet, it is greatly affected by vibrations of the machine itself and noise from peripheral equipment. This increases the possibility of false positives.

The above photos show some of the things that can affect the magnetic field of a needle detector and cause false positives.
A needle detection response may occur even though there are no foreign objects such as broken needles mixed in. False positives can also be caused by surrounding environmental factors or by the product itself, in addition to vibration.
Even non-magnetic materials (items that do not react to magnets) may be affected by magnetic fields.
For example, there are reports that petroleum-based materials such as nylon and urethane affect the magnetic field and cause false positives. These reactions are called material effects.

In some cases, these false positives may be in the opposite direction of the iron-based reactions, and in some cases, the reactions may cancel each other out, leading to missing the folded needle that should be detected (false negatives). Therefore, Hashima recommends one-by-one needle detection of the product.

*1 Shedding

The above photos show some of the things that can affect the magnetic field of a meter reader and cause false readings.
A meter reading response may occur even though there are no foreign objects such as broken needles mixed in. False positives can also be caused by surrounding environmental factors or by the product itself, in addition to vibration.
Even non-magnetic materials (items that do not react to magnets) may be affected by magnetic fields.
For example, there are reports that petroleum-based materials such as nylon and urethane affect the magnetic field and cause false detection. These reactions are called material effects.

In some cases, these false positives may be in the opposite direction of the iron-based reactions, and in some cases, the reactions may cancel each other out, leading to missing the folded needle that should be detected. Therefore, Hashima recommends a single-page needle reading of the product.

*One piece at a time