Views: 3 Author: Site Editor Publish Time: 2019-06-01 Origin: Site
The principle of magnetic induction is to measure the thickness of the coating by using the magnetic flux of the probe through the non-ferromagnetic coating into the iron substrate. The thicker coating, the smaller is the magnetic flux. Because it is an electronic instrument, it is easy to calibrate, which can perform a variety of functions, expand the range, improve the accuracy,because the test conditions can be reduced a lot, it is more extensive than the magnetic suction application field.
When the probe around the coil on the soft iron core is placed on the object to be tested, the film thickness meter automatically outputs the test current. The magnitude of the magnetic flux affects the magnitude of the induced electromotive force, and the instrument amplifies the signal and then indicates the thickness of the coating. The early products were indicated by the meter, and the accuracy and repeatability they were not good. Later, the digital display was developed and the circuit design was becoming more and more perfect. In recent years, the introduction of microprocessor technology and electronic switches, frequency stabilization and other latest technologies, a variety of patented products have come out one after another, the accuracy has been greatly improved, it is reaching 1%, the resolution reaches 0.1μm, the measurement of magnetic induction thickness gauge The head is mostly made of mild steel as the magnetic core, and the frequency of the coil current is not high, so as to reduce the influence of the eddy current effect, the probe has a temperature compensation function. Because the instrument is intelligent, it can recognize different probes, match different software and automatically change the probe current and frequency. One instrument can be used with a variety of probes, or the same instrument can be used. It can be said that instruments are suitable for industrial production and scientific research have reached a very practical stage.
The thickness gauge developed by the electromagnetic principle is applicable in principle to all non-magnetic coating measurements, and generally requires a basic permeability of more than 500. If the cladding material is also magnetic, the aluminium sheet thickness gauge requires a sufficient difference from the magnetic permeability of the substrate (such as nickel plating on steel). The magnetic principle thickness gauge can be applied to paint coatings for precise measurement of steel surfaces, porcelain, enamel protective layers, plastics, rubber coatings, various non-ferrous metal plating layers including nickel-chromium, various anti-corrosion coatings for the chemical petroleum industry. Floor. For film production industries such as photographic film, capacitor paper, plastics, and polyester, measurement platforms or rolls (manufactured by steel) can also be used to achieve measurement at any point on a large area.
