Magnetic Particle Inspection (MPI) — also called Magnetic Testing (MT) — is a Non-Destructive Testing (NDT) method used to detect surface and near-surface flaws (like cracks, laps, and inclusions) in ferromagnetic materials such as iron, nickel, and cobalt. It works by applying a magnetic field to the part and then spreading fine magnetic particles, which accumulate at discontinuities and make defects visible for inspection.
Key points about MPI:
- Suitable for ferromagnetic materials only (non-ferrous metals like aluminum or most stainless steels are not inspectable by MPI).
- Used extensively for welds, castings, and structural components in industrial facilities.
- Can be performed with visible or fluorescent particles, depending on lighting and sensitivity requirements.
- It’s fast and cost-effective with relatively simple surface preparation.