When to Use Magnetic Particle Inspection
Magnetic Particle Inspection (MPI) is a non-destructive testing technique used to detect surface and slightly subsurface flaws in most ferromagnetic materials such as iron, nickel, and cobalt, and some of their alloys.
What Magnetic Particle Inspection Detects
Moreover, MPI is a very effective method for locating surface breaking and slight sub-surface defects. Specifically, these include:
- Cracking
- Pores
- Cold lap
- Lack of sidewall fusion in welds
Magnetic Particle Inspection Techniques
There are many different techniques for conducting MPI. However, the most versatile technique is using a 110v AC hand held electromagnetic yoke magnet. Additionally, a white strippable paint is applied as contrast background and a magnetic “ink” composed of iron powder particles in a liquid carrier base.
How Magnetic Particle Inspection Works
First, the area is magnetised with the yoke magnet. Subsequently, in the event of a surface or slightly sub surface defect being present, the lines of magnetic force will deform around the defect.
Next, the magnetic ink is applied and the iron powder particles will bridge the gap caused by the defect. As a result, this gives a visible indication against the white contrast background.
Applications of Magnetic Particle Inspection
MPI provides very good defect resolution and is used extensively on:
- Welded fabrications in magnetic material
- Castings
- Locating fatigue cracks in items subject to cyclical stress
Need Magnetic Particle Inspection Services?
Whether you require MPI testing for welded fabrications, castings, or fatigue crack detection, Sutro Group provides comprehensive magnetic particle inspection services across the UK and Europe.
Contact Sutro Group today to discuss your NDT requirements.