Inspections under the Eddy Current technique

Eddy Current is the method of induced currents based on the principles of electromagnetic induction, where an alternating magnetic field induces current on the ...

Thursday July 11th, 2019 01:25 PM
Written by Apolinar Noriega

Eddy Current is the method of induced currents based on the principles of electromagnetic induction, where an alternating magnetic field induces current on the test piece made of a conductive material.

This technique is used to identify a wide variety of physical, structural and metallurgical conditions in ferromagnetic or non-ferromagnetic metal parts, and in non-metallic parts that are electrical conductors, which is why it is one of those used in the inspection of railway tracks. .

In addition, during the application of this method it is not necessary to make direct electrical contact with the piece subjected to inspection.

On the other hand, it is one of the techniques of non-destructive testing that has a scope of application in the superficial and sub-superficial vicinity of the materials subjected to the inspection.

Main applications of the Eddy Current technique

Thanks to the characteristics of the material and the versatility of the test, it has three main applications: detection of discontinuities, measurement of material properties and dimensional measurements.

1. Detection of discontinuities: surface and sub-surface type cracks, seams, corrosion, erosion and / or mechanical damage to the surface of the pieces.

2. Properties of materials: Using induced currents, material properties can be determined, including measurements of conductivity, permeability, hardness, heat treatment condition, classification of alloys and metallographic conditions.

3. Dimensional measurements: Measurement of thicknesses of a non-conductive coating on a conductive metal, with very good accuracy for small thicknesses and a little less for large thicknesses; thicknesses of coatings such as paints or insulating films, or the thickness measurement of a non-magnetic metal coating on a magnetic metal.

Industries where it is most demanded

Contact inspections of high and low frequency are highly demanded in the non-destructive testing industry.

For this reason, specialists must have a collection of suitable probes to carry out multiple tests with this technique.

Although a great variety of industries demand this type of tests, they are the maintenance railroad and the aeronautical one where the greater number of inspection requests is focused under the Eddy Current technique.

 

 

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