MAGNETIC PARTICLE INSPECTION
Magnetic Particle Inspection (MPI) is a non-destructive testing method used to find surface and near-surface cracks or flaws in ferrous (iron-based) materials.
OVERVIEW
What is Magnetic Particle Inspection?
Magnetic Particle Inspection (MPI) is a non-destructive testing method designed to detect surface and near-surface defects in ferromagnetic materials like iron, nickel, cobalt, and steel.
The process begins by magnetising the component using an electrical current or a permanent magnet. If a defect, such as a surface crack, manufacturing seam, lap, or grinding line, is present, it disrupts the magnetic field, causing the magnetic flux to leak out at the site of the flaw.
When iron particles, either as a dry powder or suspended in a liquid solution, are applied to the surface, they are drawn magnetically to these leakage fields. This cluster of particles creates a sharp, visible indication that outlines the exact location and shape of the defect.
While highly effective and reliable for finding shallow flaws, MPI is strictly limited to magnetic metals and cannot detect deep, completely internal irregularities.
HOW IT WORKS
The Process
APPLICATIONS
Where is MPI Used?
Aerospace: Checking aircraft parts such as engine mounts, landing gear and turbine blades for cracks.
Automotive: Testing important engine and steering components for faults and cracks.
Railways: Inspecting train wheels, axles, rails and couplings for fractures.
Structural Welding: Checking welds in bridges, buildings and offshore platforms for defects.
Oil & Gas: Inspecting pipelines, tanks, valves and drilling equipment for cracking.
Power Generation: Checking turbines, boilers and nuclear reactor components during maintenance.
Manufacturing & Forging: Inspecting cast and forged parts and heavy machinery for surface cracks before assembly.
MATERIALS
Suitable Materials
Magnetic Particle Inspection can be used on materials including:
Carbon steels
Low-alloy steels
Tool steels
Cast iron
Some nickel and cobalt alloys
Forged and welded steel components
EQUIPMENT
Inspection Equipment
MPI Testing. Identify defects amongst ferrous/magnetic materials.