ET- Eddy Current

ET - Eddy Current

Eddy Current Inspection (ET) is based on the principles of electromagnetic induction and is used to identify or differentiate among a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferromagnetic and nonferromagnetic metals and metal parts.

Eddy current inspection can be used to:

  • Measure or identify such conditions and properties as electrical conductivity, magnetic permeability, grain size, heat treatment condition, hardness, and physical dimensions
  • Detect seams, laps, cracks, voids, and inclusions.
  • Sort dissimilar metals and detect differences in their compositions, microstructure, and other properties.
  • Measure thickness of a nonconductive coating on a conductive metal, or the thickness of a nonmagnetic metal coating on a magnetic metal
  • Uniform thinning
  • Localized defects
  • Measurement of residual thickness
  • Measurement of the penetration of the defect





ET inspection is extremely versatile; the method can be applied to many inspection problems provided the physical requirements of the material are compatible with the inspection method.



Some variables in a material that are not important in terms of material or part serviceability may cause instrument signal that mask critical variables or are mistakenly interpreted to be caused by critical variables.