Toward the end of this decade, our industry will realize a full century since the inception of the magnetic particle inspection method. Since that discovery by Alfred Victor de Forest in 1928, this methodology has been the inspection of choice for production and in-service surface and near-surface discontinuity detection for nearly every form of ferromagnetic component. It has been adopted across the petrochemical, marine, railway, automotive, and aerospace industries as a relatively quick, inexpensive, and accurate evaluation to assure product integrity. Unbeknownst to the average person, this inspection method has been used to assure the quality of their automobile engine/drivetrain, motorboat/aircraft engine, rail car/track, firearm, or building structural weldment. Figure 1 illustrates multiple grinding crack indications on an aircraft gear using fluorescent magnetic particle testing.
As this anniversary approaches, it is helpful to evaluate the recent developments of this important technology. These improvements include the materials used in the process, the equipment used to magnetize the test subjects, the methodology to determine adequate magnetic flux density as well as the lamps used to illuminate fluorescent magnetic particle indications.