Because of the “skin effect”, the strongest eddy currents form on the periphery of the product to be tested; with growing distance from the periphery their strength drops rapidly. That is why eddy current testing is categorized as surface technique, which principally can be used for all electrically conductive materials.
Since the nature of the eddy currents is affected by numerous properties of the product to be tested, there are diverse fields of application for eddy current testing (e.g. testing for material defects, determination of wall thickness, measurement of material characteristics for sorting purposes, measurement of layer thicknesses, and many more). Compared to other non-destructive testing methods the eddy current method is characterized by the following benefits:
– Contactless,
– No preparation or subsequent treatment of the surface necessary,
– No coupling media necessary,
– High testing speeds possible (up to several m/s).
With such characteristics, it is highly suitable for use in automated testing systems.