- Home
- Techniques
- Magnetic Particle Testing
Technique · MT
Magnetic Particle Testing
Precise detection of surface and near-surface flaws in ferromagnetic materials.
What it is
Magnetic particle testing detects surface and near-surface discontinuities in ferromagnetic materials, such as cracks, laminations, lack of penetration, laps and segregations.
A magnetic field is generated in the part. Where there is a flaw, the field "leaks" out of the material and attracts the magnetic particles applied to the surface, forming a clear indication of the defect.
How the test works
- Surface preparationThe area is cleaned and access conditions are checked.
- MagnetisationA magnetic field is applied, for example with a yoke, in two directions to cover all crack orientations.
- Particle applicationVisible or fluorescent particles, dry or wet, are applied during magnetisation.
- InspectionIndications are viewed under suitable lighting; for the fluorescent method, under UV light.
- Evaluation and reportIndications are recorded and, when required, the part is demagnetised.
Where we apply it
- Gears, shafts and mechanical components
- Carbon steel welded joints
- Naval and offshore structures
- Ferromagnetic forgings and castings
What it detects
- Cracks
- Laminations
- Lack of penetration
- Laps and segregations
Advantages
- Detects surface and near-surface flaws with high precision
- Fast, with immediate results
- Very sensitive to fine cracks
- Portable equipment, ideal for field work
Limitations and precautions
- Only applicable to ferromagnetic materials
- Requires magnetisation in more than one direction
- The part may need to be demagnetised after testing
Frequently asked questions
Does magnetic particle testing work on stainless steel?
Only on ferromagnetic stainless steels. For austenitic stainless steel (the most common type) and aluminium, liquid penetrant testing is recommended.
What is the advantage of fluorescent particles?
Under UV light, indications have much higher contrast, increasing sensitivity to fine cracks.
Shall we inspect your equipment?
On site, in the workshop or at your supplier, with a technical report at the end.