Classification of coating thickness measurement gauge (1)

1.Principle of magnetic suction measurement and thickness gauge

The amount of suction between the permanent magnet (probe) and the magnetically permeable steel is proportional to the distance between the two, which is the thickness of the coating thickness measurement gauge. Using this principle to make a thickness gauge, measurements can be made as long as the difference in magnetic permeability between the cladding and the substrate is sufficiently large. In view of the fact that most industrial products are formed by structural steel and hot-rolled cold-rolled steel sheets, magnetic thickness gauges are the most widely used. The basic structure of the thickness gauge consists of magnetic steel, relay spring, scale and self-stop structure. After the magnetic steel is attracted to the object to be tested, the measuring is gradually elongated and the pulling force is gradually increased. When the pulling force is just greater than the suction force, the thickness of the coating layer can be obtained by recording the pull-down force at the moment of the magnetic steel . New products can automate this recording process. Different models have different ranges and applications.

2.Principle of magnetic induction measurement

When the principle of magnetic induction is employed, the thickness of the cladding is measured by the magnitude of the magnetic flux flowing from the probe through the non-ferromagnetic coating into the ferromagnetic substrate. It is also possible to measure the magnitude of the reluctance corresponding there is to indicate the thickness of the paint thickness measurement gauge. The thicker the coating is larger the magnetic resistance and the smaller the magnetic flux. In the case of a thickness gauge by using the principle of magnetic induction, the thickness of the non-magnetically permeable is cladding on the magnetically permeable substrate can be obtained. The substrate is generally required to have a magnetic permeability of 500 or more. If the cladding material is also magnetic, the difference in the magnetic permeability from the substrate is required to be sufficiently large (e.g., nickel plating on steel). When the probe around the coil on the soft core is placed on the sample to be tested, the instrument automatically outputs the test current or test signal. Early products used a pointer-type meter to measure the magnitude of the induced electromotive force, which was amplified by the instrument to indicate the thickness of the coating. In recent years, circuit design has introduced new technologies such as frequency stabilization, phase lock, and temperature compensation, and uses magnetoresistance to modulate measurement signals. The use of patent integrated circuits and the introduction of microcomputers have led to a significant increase in measurement accuracy and reproducibility (almost an order of magnitude). principle of modern magnetic induction thickness gauge, magnetic induction thickness gauge eddy current measurement ,magnetic suction measurement and coating thickness measurement meter eddy current thickness gauge to 0.1um, error of 1%, range up to 10mm.