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Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

Eddy Current Chapter 5 and 6

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5.1.6 Thickness measurement of non-conductive coatings<br />

5.1.6.1 Introduction<br />

The thickness of non-conducting coatings on conductors is measured by<br />

measuring the amount of lift-off the coatings produce. The technique can be<br />

applied equally to ferromagnetic or non-ferromagnetic materials, and can also<br />

be used to measure the thickness of nonconductors like plastic sheet, by<br />

laying them on top of a flat conductor. Most modern digital eddy current<br />

instruments when used in conductivity mode, provide a digital readout of both<br />

conductivity and lift off (non-conductive coating thickness). Comparative<br />

measurements can also be made using the impedance plane and are<br />

summarised as follows.<br />

Charlie Chong/ Fion Zhang

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