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Metal detector features and concepts

Views:0     Author:Site Editor     Publish Time: 2019-08-29      Origin:Site

Usually the metal detector consists of two parts, a metal detector and an automatic demoulding device. The detector is the core component. The three groups distributed inside the detector coil, namely the central transmitting coil and the two equivalent receiving coils, the intermediate oscillator of the coil transmission connection generates a high-frequency variable magnetic field, and the receiving coils on both banks are idle and disturbed in the disturbing magnetic field. . Metal detector features and concepts

The accuracy and reliability of metal detectors depend on the stability of the electromagnetic transmitter frequency, which is typically from 80 to 800 kHz. The lower the operating frequency, the better the detection performance of iron; the higher the operating frequency, the better the detection performance of high carbon steel. As the detection range increases, the sensitivity of the detector decreases, and the size of the signal depends on the size and conductivity of the metal particles.

Due to the pulsation of current and current filtering, metal detectors have certain limitations in detecting the speed of goods. If the transmission speed exceeds a reasonable range, the sensitivity of the detector will decrease.

In order to ensure that the sensitivity does not drop, a suitable metal detector must be selected to match the corresponding test product. In general, the detection range should be as small as possible, and the size of the detection channel should match the product size of the high-frequency sensitive product. The adjustment of the detection sensitivity should be determined by the center of the detection coil, and the center position is the lowest. The detected value of the product changes with changes in production conditions such as temperature, product size, and humidity, and the compensation can be adjusted by the control function. 

The ball has repeatability, minimal surface area, and the most difficult to detect metal detector. Therefore, a spherical object can be used as a reference sample for detection sensitivity. For non-spherical metals, the sensitivity of the detection is highly dependent on the position of the metal. Different locations have different cross-sectional areas and different detection effects. For example, iron is more sensitive in the vertical direction; high carbon and non-ferrous metals are less sensitive. When passing laterally, iron is not very sensitive, and high carbon steel and non-ferrous are more sensitive.

Metal detector features and concepts

In the food industry, this system typically uses a higher operating frequency. In the case of cheese foods, the response of high frequency signals will increase accordingly due to the improvement in high frequency sensing performance. Wet fat or salt substances, such as bread, cheese, sausage, etc., are the same in terms of electrical conductivity and metal. In this case, to prevent the system from having an error signal, the compensation signal must be adjusted to reduce the sensitivity.


Metal detector function: 

1) All metal detectors: iron, stainless steel, copper, aluminum and all other metals can be tested. High precision and sensitivity. 

2) Iron metal detector: It can only detect iron metal, usually called needle detector. The accuracy and sensitivity of the detection are low and it is easy to interfere. 

3) Aluminum foil metal detector: Only metal metal can be detected, but when the product is packaged in aluminum foil, the accuracy and sensitivity of detection are still high.


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