EDDY CURRENT TECHNOLOGY IN NDT

MAC’s® Eddy Current Testing (ECT) systems incorporate computer-based test instruments and test coils that use two ECT coil technologies: encircling and sector coils, and spinning or rotary probe coils.

Encircling and sector Eddy Current coil tests perform in this manner:

  • The product is passed through or adjacent to an electrical test coil, which
    has been excited by an alternating current.Non Destructive Testing Eddy Current
  • This induces a flow of eddy currents around the test material or in the
    case of a sector coil, in the area under the coil.
  • Short, intermittent anomalies or flaws cause a variation in the eddy
    current pattern, which the instrument detects.

Rotary probe Eddy Current tests perform as follows:

  • The product moves longitudinally through the rotating test probes resulting in a helical search pattern.
  • As the probe passes over a defect, variations in the induced Eddy Current pattern are detected.
  • The minimum flaw length, which can be consistently detected, is a function of the rotary speed of the probe and the throughput speed of the material.
  • Rotary testing is the method of choice for detecting seam type surface defects in non-magnetic and magnetic grades of wire and bar.
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