The Accuracy Of Metal Detectors

The accuracy and reliability of the metal detector depend on the stability of the frequency of the electromagnetic launcher, generally operating frequency from 80 to to 800 kHz. The lower the working frequency, the better the detection performance of metal; the higher the working frequency, the better the detection performance of high carbon steel. The sensitivity of the detector decreases with the increase of the detection range, and the magnitude of the induced signal depends on the size and conductivity of the metal particles.

In order to ensure that the sensitivity does not drop, it is necessary to choose the appropriate metal detector to adapt to the corresponding products tested. Generally speaking, the detection range can be controlled as minimum as possible. For high frequency sensing products, the channel size of the detector should match the product size. The adjustment of detection sensitivity should be based on the center of the detection coil, and the minimum induction at the center position. The detection value of the product will change with the change of production conditions, such as temperature, product size, humidity and other changes, can be adjusted by the control function compensation

Due to the fluctuation of current and the reason of current filtering, the accuracy of metal detector is related to the speed of conveyor belt. If the speed exceeds the reasonable range, the sensitivity of the detector will decrease.

The sphere has repeatability and minimum surface area, and it is the most difficult to detect for metal detector. Therefore, the sphere can be used as a reference sample for detection sensitivity. For non spherical metal, the detection sensitivity depends largely on the location of the metal, different positions have different cross-sectional area, the detection effect is also different. For example, the iron is more sensitive to the longitudinal pass; and the high carbon steel and the non ferrous are less sensitive. The iron, not too sensitive and non sensitive high carbon steel and iron.

The metal detector is suitable for many industries, but in the food industry, the system usually uses a higher working frequency. For cheese foods, the high frequency response will be proportionally increased due to its inherent high frequency induction performance. Wet fat or salt material, conductive properties such as bread, cheese, sausage and the same metal, in this case, in order to prevent the system error signal detector sensitivity must be adjusted, in order to achieve the detection sensitivity of the food industry, accurate requirements