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We use magnetic particle inspection for the detection of surface or near surface
discontinuities in ferromagnetic materials such as steel and iron.
With this system, we apply a magnetic field to the item being tested. If there is a flaw, the magnetic field is distorted and leaks into the air. Fine iron particles are then applied to the surface of the test item. These are attracted to the area of the flux leakage and create a visible flaw
indication.
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The iron particles can be applied dry, wet, suspended in a liquid, coloured or
fluorescent. The objective is to present as great a contrast as possible between the crack
indication and the material background.
Magnetic particle inspection detects not only those defects normally invisible
to the unaided eye but also sub-surface flaws. With sub-surface flaws it should be noted that, the further the magnetic field
travels from the surface, the less effective the technique becomes.
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