Thickness Measurement of Nickel Plating on the Back Side using a Combined Magnetic Field with AC of Two Different Frequencies

Nickel plating is used on the surface of rolled steel plates in paper mills. And it is important to monitor the thickness of the nickel layer of the nickel plating plate. In this research, the electromagnetic inspection method for the thickness of the nickel plating using the difference in electromagnetic properties between the nickel and the base material steel is proposed. On the other hand, the nickel plating plates have mechanical limitations in the papermaking process, so it is necessary to evaluate the thickness of the nickel layer from the back side of the nickel plating plate. Therefore, the electromagnetic inspection method for measuring the thickness of nickel plating on the back side using a combined magnetic field of two different frequencies is proposed. In this proposed method, it is possible to measure the nickel plating thickness of about 50 μm from the back side of the nickel steel plate.