Eddy Current Array Surface Inspection
A multiplexed eddy current method utilizing numerous closely spaced coils for rapid, areal detection of surface defects in a single pass. It replaces time-consuming manual single-probe inspections.
Eddy current testing with array probes is basically like normal eddy current testing, except you pull multiple coils over the surface at the same time. This gives you a surface image of the material condition and you find cracks or pores that you easily overlook with a single probe. It's important that the probe sits cleanly and you keep the distance to the workpiece constant – otherwise you get interference signals. Evaluation is done via phase angle and amplitude, so first learn how a clean signal differs from a flaw signal. You have to calibrate the thing on a reference piece with known flaws before you go to the component, and you document the settings precisely for later assessment.