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Magnetic Particle Inspection

The Magnetic Particle Inspection (MT) Process is a low-cost method of performing a non-destructive examination (NDE) of ferromagnetic material. Magnetism has been used to check for defects as early as 1868, when it was used to check for cracks in magnetized cannon barrels using a compass. Magnetic Particle Inspection is a moderately simple concept. It is the process of looking for leakage in magnetic flux field. Once the part being tested is magnetized, it becomes polarized – the north pole being where the magnetic force exits, and the south pole where it enters.

An example of this can be seen with a magnet that is broken in half. Each piece is a complete magnet with a north and south pole. Similarly, if there is a crack on the surface, poles will start to form on either side. The magnetic field around the crack will change, exiting at the north and reentering at the south pole. When this field spreads out, it gives a similar appearance to leaking out of the material and is therefore called a magnetic flux leakage field. The crack or flaw causing this disruption in the magnetic field is called a “discontinuity”.

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Applicable specifications

Specification	Type/Class/Limitations	Description
ASTM E1444 Standard Practices for Magnetic Testing
SS8805 Inspection Process, Magnetic Particle (Sikorsky)
EMS 92367 Magnetic Particle Inspection (Honeywell)
Mil-Std-1907

Frequently Asked Questions

The Magnetic Particle Inspection Process

The process of Magnetic Particle Inspection is relatively straightforward; however, surface preparation is a critical first step. This generally requires a chemical cleaning process using soaps, organic solvents, descaling solutions, or other processes.

Next, a magnetic field must be introduced into the part. Once the part is magnetized, small ferromagnetic particles such as iron powder are added. The excess is carefully removed, usually by some form of air stream. Afterwards, the part is inspected for any indications of cracks. Any area where the ferromagnetic material remains indicates a defect.

Finally, the part must be rotated 90 degrees and the process repeated, because discontinuities parallel to the lines of magnetic flux will not result in leakage. The primary advantages to using Magnetic Particle Inspection are speed of the examination, the low cost of the process, and the fact that defect indications are directly visible on the material’s surface.

Electrolurgy uses state-of-the-art Magnaflux test units to provide fast, efficient, and accurate Magnetic Particle Inspection services. For more information about Magnetic Particle Inspection process, please contact us directly.
FLUORESCENT PENETRANT INSPECTION

The Fluorescent Penetrant Dye (FP) process is one of the oldest forms of non-destructive testing. It is widely used due to the ease of the process and because it can be used on almost any material. Liquid Penetrant Dye testing uses capillary action to reveal surface breaks and makes the flaws appear larger. It provides a high contrast between background and the indicator, making defects easier to identify.

At Electrolurgy, we hold various certifications for dye penetrant inspection, and specialize in the testing of critical components for demanding industries such as aerospace & defense. We offer several variations, including water washable, lipophilic, and hydrophilic penetrant methods to accommodate a wide range of materials, discontinuity types, and sensitivity requirements.
APPLICABLE SPECIFICATIONS:
- ASTM E1417 Standard Practice for Liquid Penetrant Testing
- SS8806 Inspection, Liquid Penetrant (Sikorsky)
- SS8813 Non-Destructive Testing Inspection Plan (Sikorsky)
- EMS92358 Penetrant Inspection (Honeywell)
- Mil-Std-1907

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