Layer Thickness Gauge Eddy Current Principle
Eddy current thickness measurement is mainly applied to the measurement of various non-metallic coating layers on metal substrates. The use of high-frequency alternating current in the coil as a probe to generate an electromagnetic field, the probe is close to the conductive metal body, the formation of eddy current in the metal material, and with the distance from the metal body decreases and increases, the eddy current will affect the magnetic flux of the probe coil, so the amount of this feedback effect is expressed in the size of the distance between the probe and the base metal of a quantitative value, because the probe is used to measure the thickness of the cladding layer in a non-ferromagnetic metal matrix, so usually we call the probe as a non-magnetic probe. This is why we usually refer to this probe as a non-magnetic probe. Non-magnetic probes generally use high-frequency, highly permeable materials for the core of the coil, often made from platinum-nickel alloys and other new materials. Comparison with the magnetic measuring principle, their electrical principle is basically the same, the main difference is that the probe is different, the frequency of the test current is different, the signal size, scale relationship is different. In the thickness gauge, through continuous improvement of the probe structure, in conjunction with microcomputer technology, by automatically identifying different probes to call different control procedures, respectively, the output of different test currents and change the scale of the transformation software, finally make two different types of probes connected to the same thickness gauge, reduce the burden on the user, based on the same idea, can be fitted with up to 10 kinds of side head of the thickness gauge greatly expand the range of thickness measurement (up to 100,000 times or more), can be used to measure the thickness of the probe, the thickness of the probe, the thickness of the probe, the thickness of the probe, the thickness of the probe, the thickness of the probe, and the thickness of the probe. Up to more than 100,000 times), can be measured, including non-conducting magnetic materials on the surface of the magnetic cladding, non-conductive materials on the non-conductive cladding and non-conductive materials on the conductive layer, basically meets the industrial production of most of the industry's needs.
Using eddy current principle of thickness gauge, in principle, all conductive body on the non-conductive body cladding can be measured, such as aerospace aircraft surface, vehicles, home appliances, aluminium alloy windows and doors and other aluminium products on the surface of the paint, plastic coatings and anodic oxidation film. Some special applications such as diamond plating on certain metals and other non-conductive spray plating layer. Cladding materials can also have a certain degree of conductivity, through the calibration of the same can also be measured, but the conductivity of the two requirements of the ratio of at least 3 to 5 times more than the difference (such as chrome plating on copper).
