Due to the current pulsation and current filtering, the metal detector has a certain limit on the conveying speed of the tested articles. If the conveying speed exceeds a reasonable range, the sensitivity of the detector will decrease. In order to ensure that the sensitivity does not decrease, an appropriate metal detector must be selected to adapt to the corresponding tested products. Generally speaking, the detection range shall be controlled at a small value as far as possible. For products with good high-frequency induction, the size of detector channel shall match the product size. The adjustment of detection sensitivity should refer to the center of the detection coil to determine the induction of the center position. The detection value of the product will change with the change of production conditions, such as temperature, product size, humidity, etc., which can be adjusted and compensated through the control function
Spheres have repeatability and small surface area, which is also difficult to detect for metal detectors. Therefore, the sphere can be used as a reference sample for detection sensitivity. For non spherical metal, the detection sensitivity of metal detector largely depends on the position of metal. Different positions have different cross-sectional areas, and the detection effect is different. For example, when passing longitudinally, iron is more sensitive; High carbon steel and non iron are less sensitive. When passing laterally, iron is less sensitive, while high carbon steel and non-iron are more sensitive.
In the food industry, the system usually uses a high operating frequency. For foods such as cheese, due to its inherent good high-frequency sensing performance, it will increase the response of high-frequency signals in proportion. Wet fat or salt substances, such as bread, cheese and sausage, have the same conductivity as metals. In this case, in order to prevent the system from giving wrong signals, the compensation signal must be adjusted to reduce the induction sensitivity.
