Magnetic particle inspection (MPI) utilizes electro-magnetization and can be used on ferrous and nickel-based alloys that can be magnetized. The part to be inspected is magnetized by running a polarizing current through it. A solution of iron oxide powder in a kerosene-based suspension is applied to the magnetized part. Surface discontinuities and any discontinuities just below the surface fluoresce under black light. The process is very quick as the magnetization gives immediate results for exposing discontinuities. Once the inspection is complete, the part is de-magnetized and returned to its manufacturing processing and ultimately its application.
