Magnetic Particle Testing

MT is a nondestructive testing method utilized for detecting surface and very near-surface discontinuities in ferromagnetic materials.

Parts that are being examined can either have the magnetic field induced by direct or indirect magnetization.

Bench directly or indirectly induces magnetic fields. 

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Coils, Yokes, and wrapped cable indirectly induce magnetic fields

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Dry Mag Particle

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Wet Particle (Bath)

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Current used in MT testing can be either AC or DC

AC is best for tight surface discontinuities due to "skin effect

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Advantages of MT

  • Quick & Uncomplicated

  • Immediate indication of discontinuities 

  • Most reliable for surface discontinuities

  • Portable 

  • Relatively inexpensive 

Disadvantages of MT

  • restricted to ferromagnetic materials

  • Power supply needed for most techniques

  • Cannot be used on thick painted materials

  • Surface condition can effect results

  • Paints and particle can be hazardous