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Metal Detector Working Principle

Jun 29,2022

The working principle of food metal detectors generally has the principle of magnetic induction and the principle of electromagnetic induction.


The gold detector with magnetic induction principle uses a high-strength permanent magnet. The food metal detector generates a magnetic field from a permanent magnet. The receiving coil detects the change of the magnetic field. When the ferromagnetic metal passes, the ferromagnetic metal disturbs the change of the magnetic field. The receiving coil generates a weak voltage signal that is processed by the back-end circuit for detection purposes. The principle of magnetic gas induction can only detect magnetic conductive metals: such as iron, can not detect stainless steel 304, copper, aluminum, lead, tin and other metals.


The gold detector of the electromagnetic induction principle adopts a balanced coil, and generates alternating high-frequency electromagnetic fields through the transmitting coil. The receiving coils distributed on both sides of the transmitting coil are balanced coils, and are connected in reverse phase. When no metal signal passes, the coil is received. The voltage is zero. When the magnetic metal and the non-magnetic metal pass through the two receiving coils, a signal change occurs, and the food metal detector can determine whether or not the metal foreign matter is contained according to the voltage signal change.


At present, stainless steel 304 (even 316), copper, aluminum and other non-magnetic metals are commonly used in food factories. Therefore, food metal detectors with balanced coils are widely used, and ferromagnetic food metal detectors can cause non-magnetic Metal foreign body pollution.


The above briefly introduces the principle of the metal detector. If you have any questions, you can consult our customer service online.