Eddy Current – ET

Eddy Current (ET) utilizes electromagnetic induction to detect flaws in conductive materials. Eddy Current (ET) is induced when an alternating current (AC) is applied via probe or coil on the test piece. A frequency is chosen and a magnetic field forms around in and around the test piece. The flow of eddy current will be changed due to change in conductivity or magnetic permeability due to discontinuities.

This change in current flow is measured against known values and is shown on a screen for simple interpretation by our technicians. Eddy Current (ET) is therefore used to detect very small discontinuities on or near the surface, and the test surface requires little to no pre-cleaning or preparation. ET is typically utilized in the aerospace, crane, and concrete industries where a protective surface coating is already applied and cannot be removed. Seeing that this test method is sensitive to a material’s conductive properties and magnetic permeability, it can be used for material identification. Eddy Current testing can be performed by either continuous wave or pulsed. Inspections can also be performed at very high temperatures seeing that this test method is no-contact. ET is best used to detect very small cracks on or near the surface, to measure coating thickness, to investigate parts with a complex design, and to measure electrical conductivity.