MPI
Magnetic Particle Inspection
Reveals surface and near-surface defects in ferromagnetic parts using magnetic fields and fine particles.
- Method code
- MT
- Materials
- Ferromagnetic metals
- Product forms
- Welds, forgings, castings, machined parts
- Standards
- EN ISO 9934, ASTM E1444, ASTM E709
Magnetic particle inspection finds cracks at and just below the surface of steel and other ferromagnetic components, by making the flaw itself hold the indication that reveals it.
How it works
A magnetic field is induced in the part. Where a discontinuity interrupts that field, some of the flux leaks out at the surface. Fine ferrous particles are then applied, either as a dry powder or suspended in a carrier fluid, and they gather at the leakage field to form an indication that follows the shape of the flaw. Fluorescent particles are read under ultraviolet light; colour contrast particles are read under white light.
What it detects
Surface-breaking and slightly subsurface discontinuities, including fatigue cracks, grinding and quench cracks, laps and seams in wrought material, and toe cracks and lack of fusion in welds. Because the indication is held magnetically, very tight cracks that would be difficult to see by eye are made visible.
Typical applications
Welded fabrications, forged and cast components, and fatigue-critical parts examined in service. It is a routine first-line method wherever the material is ferromagnetic and the concern is cracking at the surface.
Sectors this method is used in
Other testing methods
Aircraft on the ground
Rapid Aircraft on Ground response to keep your aircraft safe and your operation moving.
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Dye Penetrant Testing
Highlights surface-breaking flaws on non-porous materials using a penetrating dye and developer.
Find out more
Ultrasonic Inspection
Uses high-frequency sound waves to detect internal flaws and measure material thickness.
Find out more
Phased Array Testing
Advanced ultrasonics using multi-element probes to build detailed cross-sectional views of a part.
Find out more
Where to next
Approvals
The approvals we hold for NDT inspection on all aircraft types, materials and structures.
Find out moreServices
The full range of non-destructive testing methods we carry out, in the laboratory and on site.
Find out moreIndustries
The sectors we test for, from aerospace to petro-chemical and industrial.
Find out moreContact
Speak to the sales team, or reach any of our offices 24 hours a day for AOG support.
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Ready when you are
Talk to our inspection team
Tell us what needs inspecting and we will tell you how we would approach it, what it will cost and how quickly we can be there. No obligation, and you speak to an engineer rather than a call centre.
Aircraft on ground? The AOG line is answered around the clock, every day of the year.
