Eddy Current NDT Applications - Flaw Detection

ETher NDE has all the equipment and expertise for all your application needs in eddy current (ECT) non destructive testing (NDT). The most common application is Flaw Detection, specifically Surface and Sub Surface crack detection and sub-surface corrosion detection.

Surface Crack Detection

This is normally carried out with pencil probes or 'pancake' type probes on ferrous or non-ferrous metals. Frequencies from 100 kHz to a few MHz are commonly used. Depending on surface condition it is usually possible to find cracks 0.1 mm or less in depth. Shielded probes, with their focused field, add the ability to test very close to edges or dissimilar materials such as ferrous fasteners in an aluminium structure.

Differential probes are sometimes used, particularly in automated applications, but care must be taken to ensure that the orientation of flaws is correct for detection. 


Sub-Surface Crack / Corrosion Detection

This is primarily used in airframe inspection. By using a low frequency and a suitable probe, eddy currents can penetrate aluminium or similar materials to a depth of 10 mm or so, allowing the detection of second and third layer cracking, which is invisible from the surface, or thinning of any of the different layers making up the structure.

Test frequencies are generally in the range 100 Hz to 10 kHz. Probe size should also be two or more times wider than the depth of penetration required. 


You can find out what ETher NDE Eddy Current NDT equipment and probes you can use to perform these types of detection by checking out our ECT application equipment and probes chart.

If you have further questions regarding Surface and Sub-Surface detection, please email "> and the team will be happy to assist you.


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