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Magnetic Particle Testing Lecture Guide l LESSON 1
Magnetic Fields
1. Permanent magnets and longitudinally magnetized test objects have a north and south pole.
2. Opposite poles attract each other.
3. Like poles repel each other.
4. Direct electrical contact creates a circular field.
5. A central conductor creates a circular field with no electrical contact.
6. A coil, yoke, or wrapped cables create a longitudinal field with no electrical contact.
7. A discontinuity will interfere with the magnetic field and form north and south poles that will attract
small magnetic particles applied.
Detection of Discontinuities
1. Discontinuities are imperfections that may interfere with the usefulness of an article or exceed
acceptability limits established by applicable specifications.
2. Magnetic particle testing is limited to disclosing only those discontinuities that are at, or very near, the
surface and only in magnetizable materials.
3. Electromagnetic forces act to align atomically small zones called domains in one direction within a
ferromagnetic test object.
Law of Magnetism
1. Magnetic particle testing will not work on paramagnetic/diamagnetic materials.
2. Magnetic particle testing only works on ferromagnetic materials that are strongly attracted to a magnet.
Materials Influenced by Magnetic Fields
1. Ferromagnetic materials are strongly attracted (commonly tested with magnetic particle testing).
2. Paramagnetic materials are weakly attracted (not tested with magnetic particle testing).
3. Diamagnetic materials are weakly repelled (not tested with magnetic particle testing).
4. Nonferromagnetic materials are not attracted or repelled (not tested with magnetic particle testing).
Characteristics of Magnetic Fields
1. Magnetic lines of force are strongest and most dense at the poles.
2. Magnetic lines of force always seek the shortest path of least resistance through metal.
3. Magnetic lines of force never cross each other.
4. Magnetic lines of force are called magnetic flux.
5. Magnetic lines of force only enter or leave the poles of a magnet.
6. A circular magnet with no irregularities has no poles.
7. Magnetic poles will attract magnetic particles.
Magnetic Particle Testing Lecture Guide l LESSON 1
Magnetic Fields
1. Permanent magnets and longitudinally magnetized test objects have a north and south pole.
2. Opposite poles attract each other.
3. Like poles repel each other.
4. Direct electrical contact creates a circular field.
5. A central conductor creates a circular field with no electrical contact.
6. A coil, yoke, or wrapped cables create a longitudinal field with no electrical contact.
7. A discontinuity will interfere with the magnetic field and form north and south poles that will attract
small magnetic particles applied.
Detection of Discontinuities
1. Discontinuities are imperfections that may interfere with the usefulness of an article or exceed
acceptability limits established by applicable specifications.
2. Magnetic particle testing is limited to disclosing only those discontinuities that are at, or very near, the
surface and only in magnetizable materials.
3. Electromagnetic forces act to align atomically small zones called domains in one direction within a
ferromagnetic test object.
Law of Magnetism
1. Magnetic particle testing will not work on paramagnetic/diamagnetic materials.
2. Magnetic particle testing only works on ferromagnetic materials that are strongly attracted to a magnet.
Materials Influenced by Magnetic Fields
1. Ferromagnetic materials are strongly attracted (commonly tested with magnetic particle testing).
2. Paramagnetic materials are weakly attracted (not tested with magnetic particle testing).
3. Diamagnetic materials are weakly repelled (not tested with magnetic particle testing).
4. Nonferromagnetic materials are not attracted or repelled (not tested with magnetic particle testing).
Characteristics of Magnetic Fields
1. Magnetic lines of force are strongest and most dense at the poles.
2. Magnetic lines of force always seek the shortest path of least resistance through metal.
3. Magnetic lines of force never cross each other.
4. Magnetic lines of force are called magnetic flux.
5. Magnetic lines of force only enter or leave the poles of a magnet.
6. A circular magnet with no irregularities has no poles.
7. Magnetic poles will attract magnetic particles.