Research and optimization of the eddy current transducer of dielectric coatings’ thickness on metal surfaces of products

Abstract

Main purpose of the research is to increase the technical and economic performance of eddy current transducers of the thickness of dielectric coatings.Eddy current method of dielectric coatings’ thickness measurement on metallic surfaces was improved and appropriate measuring instrument was developed. Basic task of eddy current method and eddy current measuring instrument improvement was the accuracy increase of dielectric coatings’ thickness measurement on metallic surfaces and reduction of the influence of external magnetic fields. For this reason, during the process of research relative error of dielectric coatings’ thickness measurement δ was chosen as an optimization criterion. List of pre-potent factors that make significant influence on the accuracy of dielectric coatings’ thickness measurement includes sensor’s oxide core diameter Х1, mm; oxide core’s height Х2, mm; number of turns in the energizing coil Х3, frequency of energizing coil supply voltage Х4, Hz.Mathematical methods of experiment planning theory were used to research eddy current transducers measuring dielectric coatings’ thickness following the task of increasing their technical end economic performance. Among them the cost-optimal planning of the experiment, based on the use of Gray code, and the differential method of determining the primary information parameter.The analysis of different experiment plans showed that the plan built in a traditional way has 26 transitions of different factor levels during the process of its realization, and a plan using Grey code has only 15 transitions. It makes possible to say that the new plan of experiment, built on using Grey code, has optimal number of transitions for mentioned list of factors. It makes this plan optimal taking into account cost and time expenses.Besides, to carry out the traditional plan of experiment, it was necessary to use eight prototype products of eddy current transducers. To perform eight experiments using plan based on Grey code we need only four prototype products of eddy current transducers.Applying full factor experiment, built on using Grey code, mathematical model for eddy current measuring transducers was received with transformed variables.Fulfilled experimental researches allowed to develop a prototype product of eddy current transducer of dielectric coatings’ thickness that provides good accuracy (relative error of thickness is not more than 0.3%) with simple design.