Eddy Current Testing (ET)

The flow of eddy currents is affected by fissures, constrictions or other discontinuities that cause distortions in the cross section through which the current is made to flow. Thus, the eddy current technique is useful for detecting the wall thickness of thin materials as well as measuring localized discontinuities

The thickness of the part must be within the depth of penetration (skin depth), eddy currents is dependent upon material properties and operating frequency

This method can detect very small flaws in or near the surface of the material. Changes in material thickness, and changes in material properties can also be measured

Eddy Current Testing
Eddy Current Testing (ET)

Advantages

  • Provides instantaneous results.
  • Uses portable equipment that may be readily adapted to automation
  • Causes no damage to the material
  • Is safe as a testing tool, requiring only the coupling of an alternating magnetic field

Limitations

  • Testing is limited to those metals and carbon fiber composites that are electrical conductors
  • When the test part is composed of a ferromagnetic material, the depth of penetration into the material is vastly reduced
  • Discontinuities parallel to the surface, such as laminations, are generally not detected