Magnetic Particle Inspection

MPI PRE-TEST CHECKLIST

• Review provided part specifications and prints to determine if criteria can be met.
• Level II techs develop a technique that meets customer and test specification requirements for proper inspection.
• Technique is reviewed by a Level III inspector and revised/approved as needed.
• Once approved testing can commence.

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Part being examined under flourescent light by MPI tech.

GENERAL 7-STEP INSPECTION PROCESS

STEP 1
Clean part as needed with a solvent degreaser so it's free of oils and contaminants.

STEP 2
Secure part between head and tail stock of wet bench machine. Using a "head shot," a pre-determined amount of electrical current is applied to magnetize the part according to the standard (ASTM E1444). Some test specifications call for multiple head shots.

STEP 3
Bathe part in wet flourescent suspension solution that contains iron oxide particles, as an electric current is applied.

STEP 4
With the magnetic bench machine enclosed within a darkroom enclosure, UV light is applied to identify indications of any defects that appear in relation to the direction of the magnetic field applied to the part.

STEP 5
Depending upon the specific test requirements, one or more "coil shots" may also be applied to the part to identify any discontinuities that run in the opposing direction.

STEP 6
Demagnetize the part.

STEP 7
Following this thorough visual examination, the part is accepted or rejected, based upon pre-defined criteria. Failed parts are isolated from accepted parts and tagged accordingly.

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