Features:
Ensure that the test piece is thoroughly degreased and free from corrosion and oxidation.
Clamp the test piece between the contacts on the head and tail stock of your bench unit.
Apply magnetic ink while the current is flowing.
Establish the current required to make the hole nearest the outer surface of the ring visible on the outer surface.
Further increase the current to establish indications from the other two holes on the outer surface of the ring.
Note the current required to establish each hole indication.
If the MPI process is functioning correctly each hole should be visible at each subsequent use of the test piece.
Repeat the test for each current wave form which your magnetising unit is equipped with.
Please note that the deeper hole is unlikely to positively using an alternating current wave form.