Eddy current testing is a non-contact electromagnetic testing technique used for the inspection of conductive materials without the need to remove non-conductive coatings. An alternating current is passed through a coil in order to create an alternating magnetic field which is used to induce a localised current (eddy current) into the material under test. Eddy current is routinely used to inspect a wide range of different materials and components across several fields of engineering including oil and gas, nuclear, power generation and aerospace.
A.C.F.M. is an electromagnetic technique used for the detection and sizing of surface breaking cracks in metallic components and welds and can be performed through paint and coatings. It combines the advantages of the alternating current potential drop (ACPD) technique and Eddy Current Testing (ECT) in terms of defect sizing without calibration and ability to work without electrical contact respectively. The probe introduces an electric current locally into the part and measures the associated electromagnetic fields close to the surface. The presence of a defect disturbs the associated fields and the information is graphically presented to the system operator. The ends of a defect are easily identified to provide information on defect location and length.