Eddy Current for ND Testing
Wednesday, January 16th, 2008
Non-destructive checks (ND) are performed in order to detect surface or structural defects in a part without changing its physical condition.
In modern production systems it is indispensable to automate non-destructive checks, not only due to stricter quality standards, but above all because the failure of a mechanical component may affect the user’s safety.
Checking the surface defects of parts (such as cracks, porosity, etc.), the structure of the material and the hardness and depth of hardening, the eddy-current technology offers a testing speed that is higher than that of any other technology in the area of non-destructive checks.
Operating Principle
When a solenoid charged by alternating current (control sensor) is moved close to a conducting material (part to be checked), the alternating magnetic field creates a mutual-induction current on the part.
This induced current generates a secondary magnetic field that induces a current in the coil. The impedance of this coil may be affected by differences in the structure of the material, by the hardness of the material, the depth of the hardening or the presence of cracks or pores.
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