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Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

Eddy Current Chapter 5 and 6

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To obtain adequate depth of penetration, not only must the frequency be<br />

lower than for the detection of surface flaws, but also the coil diameter must<br />

be larger. On flat surfaces, a spot probe, either absolute or reflection, should<br />

be used in order to obtain stable signals (see FIG. 5.16). On curved surfaces,<br />

a spot probe with a concave face or a pencil probe should be used. Spring<br />

loaded spot probes can be used to minimize lift-off, and shielded spot probes<br />

are available for scanning close to edges, fasteners, and sharp changes in<br />

configuration.<br />

Ways of ensuring good contact:<br />

■ Curve surface probes.<br />

■ Pencil probes.<br />

■ Spring loaded probes.<br />

Charlie Chong/ Fion Zhang

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