Eddy Current Thickness Gauge Principles and Characteristics

The coil core in the eddy current coating thickness gauge probe is usually made of a high-frequency material such as platinum-nickel alloy, which generates a high-frequency electromagnetic field in the coil by the current. After contacting of the conductor (metal substrate) at the probe and the bottom, eddy currents are formed on the metal substrate. The closer the probe is to the conductor (metal substrate),the larger the eddy current and vice versa. This eddy current will have a feedback effect on the coils in the probe. The magnitude of the feedback action can represent the distance between the probe and the conductor (metal substrate),that is,the non-conductive coating thickness on the conductive metal substrate.

The eddy current thickness measurement method can theoretically measure the thickness of the coating on the magnetic metal substrate.The calibrated instrument can measure the coating thickness with certain conductivity,but the requirements of this type of test on the substrate and the cover layer are very high,so it is not recommended.If it is necessary to measure the thickness of the coating on the magnetic metal,it is recommended to use the instrument of magnetic thickness measurement principle. The instrument using a single eddy current thickness measurement method has narrow measurement range, so gradually coating thickness gauges using both principles at the same time appear.Linshang coating thickness gauge use both magnetic and eddy current measurement principles which can be used for the measurement of non-ferromagnetic coatings on ferromagnetic metal substrates and non-conductive coatings on non-magnetic metal substrates.