The art of probes development consists in the realisation of a sensor construction that brings the required magnetic field (and thus the eddy current field) to the ‚test location‘ in the workpiece with the required test frequency, in the optimum alignment and required strength, while always minimising undesirable effects as far as possible.

Basically, there are two main groups of probes: flow sensors and tactile probes. In the case of through-flow probes, a distinction is made between: External pass-through sensor, which encloses the test object and is guided through it (e.g. rod testing with comprehensive test coils) and internal pass-through sensor, which is enclosed by the test object, i.e. the sensor is guided through the test object (e.g. in internal pipe testing). Pass-through sensors always detect a complete circumferential section of the test object, outside or inside.

When selecting the test frequency for eddy current testing, consider the specific requirements of the application and the sensor to be used. The recommended frequency range for the sensor should be taken from the manufacturer’s sensor data sheet.