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How Much Do You Understand About Metal Detectors?

Jul 01,2022

With the gradual improvement of people's quality of life, people's requirements for products are getting higher and higher, metal detectors have entered people's field of vision, and have played a great role in controlling product quality. Next, I will give you four aspects Introduce the metal detector

Principle of metal detector

The digital metal detector is composed of two parts, namely the detection coil and the automatic rejection device. The detection coil is the core part. A central transmitting coil and two equivalent receiving coils are installed in a probe. The oscillator emits a high-frequency magnetic field through the transmitting coil in the middle, which is connected to the two receiving coils, but with opposite polarities. When the magnetic field is not disturbed by the outside world, the voltage output signals generated by them cancel each other out. Once metal impurities enter the magnetic field, this balance will be broken, and the induced voltages of the two receiving coils cannot be cancelled. The un-cancelled induced voltages are amplified by the control system, and the metal detector can detect the presence of metal and generate Alarm signal (metal impurities detected). The system can use the alarm signal to drive an automatic rejection device, etc., so as to exclude metal impurities from the production line.

Simply put, the metal detector detects metal through the principle of electromagnetic induction. The entry of ferromagnetic metals into the detection area will affect the distribution of magnetic lines of force in the detection area, thereby affecting the magnetic flux in a fixed range. Non-ferromagnetic metals entering the detection area will produce eddy current effects, and will also change the magnetic field distribution in the detection area. It has high detection sensitivity for all metals including iron and non-iron.

Detectable metal

Metal detector can be used to detect broken needles, iron wires or non-ferrous metals (lead, copper, aluminum, tin, stainless steel and other non-ferrous metals) that are included or lost in raw materials or products. Even fine metal embedded in the product can be identified.


Accuracy and reliability of metal detector

The accuracy and reliability of the metal detector depends on the frequency stability of the electromagnetic transmitter, and generally use the operating frequency from 80 to 800 kHz. The lower the working frequency, the better the detection performance of iron; 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 size of the induced signal depends on the size of the metal particles and the conductivity. Due to current pulsation and current filtering, food metal detectors have certain restrictions on the conveying speed of the detected items. If the conveying speed exceeds a certain reasonable range, the detection sensitivity will decrease to a certain extent.


Application range of metal detector

The metal detector is widely used in food, pharmaceuticals, cosmetics, industry, textiles and clothing, toys and other industries and fields. The metal detector developed and manufactured by Shanghai Shiqian has HACCP certification for the food industry and GMP certification for the pharmaceutical industry, especially suitable for Sauce, sausage, water hinge, ham, soup, sugar products, preserved food, fresh meat, frozen food, salted food, fast food and other industries and other industries that require high detection sensitivity, anti-interference ability and waterproof .

Application range of metal detector