Quality Magazine

Nondestructive Testing Methods--How Eddy Current Ultrasonic Testing Works

April 27, 2012

Nondestructive testing (NDT), sometimes called nondestructive examination (NDE) or nondestructive inspection (NDI), is any method of materials testing whereby the material being tested is not damaged or destroyed. It is important in quality control as well as useful in research. It is also a key element in material inspection systems. Nondestructive testing, using ASNT standards, can be used to for bolt hole scanning, crack detection, flaw detection, pin hole detection, conductivity testing, thickness measurement, and corrosion detection. Two reliable nondestructive testing solutions are ultrasonic testing (UT) and eddy current testing.

How Eddy Current Testing Works

Eddy current inspection (ECI) or eddy current testing (ECT) is a type of electromagnetic testing; nondestructive testing (NDT) that relies on the principals of electromagnetism. Through electromagnetic induction, eddy currents are formed. When a periodically varying magnetic field intersects an electrical conductor, eddy currents are induced, according to Faraday