What is the main principle behind eddy current testing?

Eddy current testing is based on the principle of electromagnetic induction. Specifically, when an alternating current passes through a coil, it generates a changing magnetic field. This magnetic field induces electrical currents, known as eddy currents, in conductive materials close to the coil.

These eddy currents flow in circular paths and can create localized magnetic fields, which can be influenced by the presence of flaws, such as cracks or inclusions, in the material. The characteristics of the induced eddy currents—such as their strength and phase—change when these imperfections are present. By measuring these alterations, technicians can detect flaws without direct contact with the material.

This technique is particularly valued for its ability to inspect components without the need for external preparations, making it a non-destructive testing method that is often used in aerospace, automotive, and manufacturing sectors.

Understanding this principle is crucial for effective application in maintaining and ensuring the integrity of various components and materials.