YUHONG GROUP - Magnetic Particle Inspection

Magnetic particle inspection is a method of observing defects by using magnetic powder as a display medium. According to the type of magnetic powder medium applied during magnetisation, the inspection method is divided into wet and dry methods; according to the time when the magnetic powder is applied on the workpiece, the inspection method is divided into continuous and remanent magnetisation methods.

Ferromagnetic material workpiece is magnetised, due to the presence of discontinuities, so that the surface of the workpiece and near the surface of the magnetic lines of force of the local distortion and produce a leakage field, adsorption of the magnetic powder applied to the surface of the workpiece, the formation of visually visible magnetic traces under the appropriate illumination, which shows the location of the discontinuities, the size, shape and severity of the discontinuities. Also known as magnetic particle inspection or magnetic particle flaw detection, belongs to the non-destructive testing of one of the five conventional methods.

Characteristics:
Magnetic particle inspection can only be used to detect defects on or near the surface of ferromagnetic materials.Since the discontinuous magnetic traces are piled up on the surface to be inspected, the shape, position and size of the discontinuities can be visualised and their nature can be roughly determined.
The sensitivity of magnetic particle inspection can detect discontinuities up to a width of 0.1 μm. Using a combination of magnetisation methods, magnetic particle inspection is virtually independent of the size and geometry of the workpiece and can detect defects in all directions of the workpiece.