The coating thickness meter is an instrument used for non-destructive measurement of the thickness of the coating on the surface of metal substrates or non-metal substrates. Commonly there are high-precision coating thickness meters for magnetic and eddy current thickness measurement. The coating thickness meter of magnetic thickness measurement + eddy current thickness measurement is also called iron-aluminum dual-purpose coating thickness meter.
(1) The coating thickness meter based on the principle of magnetic measurement
There is a certain relationship between the thickness of the coating on the surface of the magnetic metal substrate and the magnetic resistance and magnetic flux. This relationship can be used to calculate the thickness of the coating on the surface of the magnetic metal substrate. The thickness of the coating is measured by the size of the magnetic flux that flows into the magnetic metal substrate through the non-magnetic coating detected by the measuring probe. In general, the thicker the coating on the surface of the substrate, the greater the magnetic resistance, the smaller the magnetic flux.
(2) The coating thickness meter based on the principle of eddy current measurement
To put it simply, high-frequency AC signals are used to generate electromagnetic fields in the probe coil, and eddy currents are formed when the probe is close to a conductor (usually metal). The size of the eddy current has a certain relationship with the distance between the probe and the conductive substrate.
When the probe of coating thickness meter is closer to the conductive substrate, the eddy current will be greater and the reflection impedance will be greater. When the probe is farther away from the conductive substrate, the eddy current will be smaller and the reflection impedance will be smaller. This value directly indicates the size between the probe and the conductive substrate, that is, the thickness of the coating.