Comparison of Sensor Structures and Evaluation Methods in Plating Thickness Evaluation using ECT

Abstract

This paper discusses about plating thickness sensors with the eddy current for the continuous galvanizing line. We propose that separation index which shows distance between detection signals on the complex plan in order to compare between sensors, and a thickness evaluation method in order to evaluate plating thickness from detection signals. In simulations and experiments, a measurement condition and a best sensor of three sensors was quantitatively selected by using the index. Plating thickness of a test sample was evaluated with the method which use the radial basis function interpolation. These results demonstrate the possibility of making thickness measurements using an eddy current with high and variable liftoff.