Technology
Eddy Current Technology (ECT)
ECT is based on the physics phenomenon of electromagnetic induction: an alternating current flowing through a coil instantly generates an oscillating magnetic field. If the coil and its magnetic field approach an electrically conductive material, a circular flow of electrons, known as eddy current, is induced in this electrically conductive material. In turn, this eddy current generates its own magnetic field, which will interact through mutual inductance with the coil and its magnetic field. Defects in the material (cracks, pitting, wall loss, or other discontinuities) disrupt the flow of the eddy current and its magnetic field, thus also modifying the electrical impedance of the coil.
Eddy Current Array (ECA)
ECA probes use a number of individual coils grouped together in one assembly. These coils are used in a multiplexed sequence to eliminate interference (mutual inductance) between coils in close proximity. Coils work together to scan a wider inspection area than conventional coil probes. To optimize performance, array probes can be made flexible or shaped to match the geometry of the part to inspect. Data from ECA probes, which can be encoded, is transmitted directly to software for graphical display (C-scans), record keeping, and reporting.
Slow raster scan Fast array scan
ECA probes can be used in lieu of magnetic particle, liquid penetrant and single-element ECT to significantly reduce inspection time, improve flaw detection, and provide full inspection records. Eddyfi offers a complete line of eddy current data acquisition instruments as well as advanced eddy current analysis software.
Benefits of ECA
• Faster inspections
• Better stability during inspection over complex geometries (vs. ECT)
• Improved flaw detection
• Indication sizing and positioning possible through encoded output
• Computer-based data records and reports for audit trails
• Simpler scan patterns and lower-cost scanners (vs. ECT)
• Allows the inspection of difficult or limited access (vs. PT, MT)
• Chemical-free, no-clean up, green, and HSE-friendly inspection (vs. PT)
• Easy to combine with UT or PA for single pass inspection (vs. PT, MT)
ECA probes eliminate one motion axis by using multiple coils to cover a wider area, consequently significantly reducing inspection time. In many cases, a simpler, more affordable, one-axis manual scanner can replace more expensive two-axis scanners. ECA probes can be built in the exact shape of a particular part for simplified, one-pass inspection.
Array probes can be manufactured with a wide variety of coil sizes and types based on the properties of the defect to find (size, orientation, depth, type, etc.), on material properties, and on surface properties. Furthermore, to deliver the best performing probe configuration, it is also crucial to carefully select the coil shape, diameter, impedance, mode of operation (absolute, differential, transmit-receive, transfo-differential, etc.), and most importantly, the operating frequency.
Eddyfi’s Magnifi™ eddy current analysis software has three independent but perfectly integrated operating modes: setup, acquisition, and analysis. In each mode, the user interface has been optimized for ease-of-use and data handling. The Windows-based program offers innovative features for defect localization and sizing, as well as numerous ways of displaying data: lissajous, strips charts, C-scans, 3D C-scans, and 3D PolarScans. Magnifi also offers detailed and customizable reporting features that can be matched to a variety of inspection needs and environments.
