How does the Magnetic Particle NDI method function?

The Magnetic Particle Non-Destructive Inspection (NDI) method functions by inducing a magnetic field in the object being inspected and then applying iron oxide particles to its surface. When a magnetic field is applied, it causes the iron oxide particles to orient themselves along the lines of magnetic flux. If there are any surface or near-surface discontinuities, such as cracks or pits, they disrupt the magnetic field, causing a concentration of the iron particles at these flaws. This visual contrast makes the defects detectable as they appear as clusters of particles, thereby allowing inspectors to identify issues without damaging the component.

The method's effectiveness lies in its ability to detect very small surface and near-surface flaws, making it a valuable tool in various industries, including aviation, where structural integrity is paramount. The simplicity of the technique and the immediate visual results it provides are significant advantages, aiding in timely inspections.