High-Precision Internal Diameter Measurements Using Eddy Current Arrays

Tubular components subjected to extreme pressure and intense wear, requiring highprecision internal-diameter measurements, were investigated. Such measurements are currently carried out using slow mechanical devices and/or costly laboratory equipment. This paper describes the development process of a new measurement tool, capable of +/0.015mm diameter evaluation, using state-of-the-art eddy current array technology. In addition to high precision sizing, the test method provides traceability, 360deg coverage and robust probes adapted to most harsh environments. Many aspects of the development are presented in this paper: eddy current coil design, mechanical probe design and implementation on commercially available Eddy Current Array NDT equipment. The various steps to obtain an operational system will be discussed: first prototypes and basic concepts, experimental results and challenges, probe improvements and evaluation of the final probe precision.