Magnetic Particle Inspection
Surface and near-surface crack detection on ferromagnetic forgings using a magnetic field and iron particles.
The part is magnetised and fine particles are applied; a surface-breaking or near-surface defect distorts the field and the particles gather at it. It is quicker and more sensitive than dye penetrant on steel forgings, which is why machined shafts, drill collars and railway parts are routinely MPI'd after final machining. Austenitic stainless and nickel alloys are not ferromagnetic, so those take dye penetrant instead.
Related terms
Where this applies
forged-shafts, closed-die-forgings
Need help applying this?
Stancor Forgings engineers answer specification questions directly. Contact us.