Overview

1. Magnetic particle flaw detection is capable of detecting cracks, non-metallic inclusions and other discontinuities on, or near, the surface of ferromagnetic materials.
2. The sensitivity of the inspection is not greatly impaired by the presence of foreign matter within the flaws such as oil, grease or grinding debris, unless the contaminant has magnetic properties similar to the test piece (which is highly unlikely). Flaws can also be detected when the surface is peened or coated with a thin layer of paint. Both BS 6072 and BS EN ISO 17638 quote a maximum thickness of unbroken paint of 50 µm (microns).
3. It is possible to inspect components that have been coated, e.g. with cadmium plate or paint, providing the coating is not too thick (usually not greater than 50 µm) with only a slight loss of sensitivity.