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   Magnetic Particle Examination is a NDE method that uses magnetism and magnetic fields to find defects in Ferro magnetic objects. Magnetic particle inspection will detect defects that are open to or slightly below the surface of the test object.

    Magnetic particle examination uses the theory that magnetic fields are very even over the surface of a magnetized object. When there is a flaw, it interrupts the even flow of magnetism. This creates a North and South pole on either side of the flaw. Very fine Ferro magnetic particles, either alone or in a liquid bath, are spread on the test object. This particle will naturally be attracted to the North and South poles of the defects. These particles will then form a representative picture of the defects. The Ferro magnetic particles are colored, to contrast the test object color. This is done so that defects may be more readily see. For additional sensitivity, particles may have a flourescent colorthat are to be viewed in a darkened area with an ultraviolet light.

    Interpretation involves comparing the indications present on the test object to indications of possible defects. the indications can be measureed and judged against specification requirements. Reportable indications shall be reported on the proper magnetic particle report form.

 

Advantages:

  • Relatively economical
  • Very sensitive to surface defects

Disadvantages:

  • Only works on Ferro magnetic objects
  • Proper surface preparation

Defects inspected for: Surface and slightly subsurface defects

 

 

 
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