Real-Time In-Process Measurement and Control of Zinc Coating Weight: Assessing Eddy Current Sensor Proficiency in Industrial Applications

Abstract

The investigation aims at evaluating the proficiency of an eddy current (ECT) sensor potential for in situ, real-time industrial applications. This sensor designed for in-process monitoring and control of zinc coating weight on GI wires, ranging from approximately 50-150 g/m2 expressed as grams per square meter (GSM). It is engineered to operate effectively in challenging industrial environments, providing immediate feedback during production, even at high speeds. In this study, an ECT sensor is configured in an encircling coil arrangement, consisting of three coils of which two transmitter coils are interconnected in a Helmholtz configuration, while the receiver coil is precisely positioned axially and concentrically between the transmitter coils. This design substantially extends the measurement region with a nearly constant magnetic field profile, making it particularly suitable for evaluating the weight of thin zinc coatings on the tested specimens. The superiority of this configuration is established through mathematical modeling, showcasing enhanced measurement accuracy and sensitivity, especially for evaluating the weight of thin zinc coatings on wires. This is further affirmed through validation and optimization via finite element method (FEM) simulations. In situ performance evaluation of the sensor system was conducted at an industrial installation, encompassing essential practical considerations, such as repeatability, reproducibility, and the influence of temperature fluctuations. The findings are in agreement with the chemical analysis (within +/- 5 %) stipulated by international regulations. The ability to consistently measure and record thin coating weight confers significant benefits, contributing to both zinc conservation and optimal quality control.