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Magnetic thickness gauge and eddy current thickness gauge are both coating thickness gauges that can be used to measure the thickness of coatings on metal substrates, but the two instruments use different measurement principles for different scenarios. The following will be distinguished from the principle test.

First, the measurement principle

1. Measuring principle of magnetic thickness gauge

The magnetic thickness gauge uses the magnetic method to measure the thickness of the coating. The principle of the magnetic method is divided into two types, so the magnetic thickness gauge is also divided into a magnetic suction coating thickness gauge and a magnetic induction coating thickness gauge.

The magnetic coating thickness gauge can judge the thickness of the coating by the magnetic attraction between the permanent magnet in the probe and the magnetic metal substrate. This thickness gauge consists of exhaust spring, magnetic steel, scale and self-stop mechanism, etc. Individual composition. After the measured magnetic metal substrate and magnetic steel are attracted, the relay spring is gradually stretched. When the tensile force is gradually increased to just larger than the suction force, the magnetic steel will detach from the magnetic metal substrate. It can be recorded, and the thickness of the coating can be measured after a certain proportional relationship.

The magnetic induction coating thickness gauge uses the principle of magnetic induction. The thickness of the coating can be determined by measuring the magnetic flux of the permanent magnet in the probe through the non-ferromagnetic coating into the magnetic metal substrate. The same, the thicker the coating, the more the magnetic flux. Small, when a certain proportional relationship is obtained, the thickness of the coating can be calculated.

Because the magnetic induction has less test conditions than the magnetic coating thickness gauge, the application range of the magnetic induction method is wider.

2. Measuring principle of eddy current thickness gauge

The eddy current thickness gauge uses the principle of eddy current. After the coil iron core in the probe is energized, a high-frequency magnetic field can occur. The size of the eddy current generated by the contact between the probe and the metal substrate to be measured reflects the probe and the substrate The distance between them is that the closer the probe is to the metal substrate, the larger the eddy current, and the smaller the distance, the smaller the eddy current. Based on this principle, the proportional relationship between the eddy current size and the interval size can be found, and the interval size can be obtained. That is the thickness of the coating.