Eddy current testing (EC)

What is Eddy Current testing?

  • Eddy Current testing is the use of electromagnetic induction to detect and characterize surface and sub-surface flaws in conductive materials
  • Eddy current sensors sense displacement  and are formed when a changing magnetic field intersects a conductor
  • Probes sense the change and find out the distance between the probe and the test material
  • Electric current is induced into the test subject and the change in the current is noticed and determines a fault. There will be a corresponding change in the phase and amplitude of the signal that is measured.
  • Eddy Current  can measure metal thickness so erosion or metal thinning can be detected
  • Eddy current is one of six methods of NDT testing: eddy current, magnetic-particle, liquid penetrant, radiographic, ultrasonic, visual testing

Advantages of Eddy Current Testing

  • Faster scanning speed than ultrasonic testing
  • Minimal preparation for surfaces to be tested
  • EC can test through several millimeters of coating
  • Very sensitive - can detect very small cracks
  • Testing devices are portable with immediate results/feedback
  • The test equipment does not need to be in direct contact with the item being tested
  • Production is not interrupted due to fast and automated testing
  • Groups of sensors can be used to provide a larger area scan

Eddy Current Applications

  • Aerospace Industry
  • Petrochemical Industry
  • Material sorting- used to determine that the proper materials are being used for a job
  • Used to determine material characteristics/purity of the metal
  • Tube and wire testing
  • Weld testing
  • Coating thickness measurement