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Magnetic Particle Inspection (MPI)

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  • Magnetic Particle Inspection (MPI)

    Magnetic particle inspection (MPI), also known as magnetic particle testing (MT), as a recognized non-destructive testing method, is used to detect cracks and other defects on surface and near-surface of ferromagnetic materials. As a professional reliability third-party testing organization, T,C&A Lab can provide magnetic particle inspection (MPI) service according to ISO, ASTM standards and industry requirements. Welcome to contact our experts for consultation.

    Magnetic particle testing methods

    • Wet method

    The use of magnetic powder suspended in oil, water or other liquid medium is called wet method, which uniformly distributes the magnetic suspension on the surface of the workpiece in the detection process, and shows the shape and size of the defect by using the flow of carrier liquid and the attraction of magnetic powder by leakage magnetic field. In the wet detection, the magnetic powder particles that can be used are smaller because of the dispersion and suspension performance of the magnetic suspension. Therefore, it has high detection sensitivity.

    • Dry method

    Dry method is also called the dry powder method. In some special occasions, when the wet method cannot be used for testing, the special dry magnetic powder is directly applied to the magnetized workpiece according to the procedure, and the defects of the workpiece show magnetic marks. Dry inspection is mostly used for local area inspection of large castings, forgings, large structures and weldments, and is usually used in conjunction with portable equipment.

    Magnetic particle inspection process

    According to the material, shape, size of the tested parts and the nature, position, direction and shape of the defects to be checked, the magnetic particle testing methods used are also different, but the general process of testing is generally as follows.

    • Preparation before testing: Check the sensitivity of the testing equipment, remove the oil and rust on the surface of the tested parts.
    • Magnetization.
    • Spray magnetic powder or magnetic suspension.
    • Observation and evaluation of magnetic marks.
    • Demagnetization.
    • Cleaning, drying, anti-rust.
    • Record the results: Record the magnetization process, specimen status, magnetization current, magnetization mode, interpretation and evaluation of magnetic marks, test date, operator and evaluator, and final test results.

    Application scope of magnetic particle inspection

    • It is suitable for detecting surface and near-surface defects of ferromagnetic materials, such as cracks with very narrow gaps between the surface and near-surface and other defects that are difficult to see with the naked eye. It is not suitable for detecting deeply buried internal defects.
    • It is suitable for the detection of Fe-Ni-based ferromagnetic materials, such as martensitic stainless steel and precipitation hardening stainless steel, but not for non-magnetic materials, such as austenitic stainless steel.
    • It is suitable for detecting unprocessed raw materials and processed semi-finished products, finished products, and in-service and used workpieces.
    • It is suitable for testing pipes, bars, plates and shapes, forging steel castings and welding parts.
    • It is suitable for detecting defects where the extension direction of the workpiece surface and near surface is perpendicular to the direction of the magnetic field line as much as possible, but it is not suitable for detecting defects where the angle between the extension direction and the direction of the magnetic field line is less than 20 degrees.
    • It is suitable for detecting small defects on the surface and near surface of the workpiece, but not suitable for detecting shallow and wide defects.

    Industries of magnetic particle inspection (MPI)

    • Aerospace
    • Automotive
    • Petrochemical
    • Structural steel
    • Power generation
    • Pipelines

    Standards we test to

    • ASTM E709-15, ASTM E1444, ASTM A275, ASTM E3024, ASTM A966, ASTM E3022-18, ASTM A986
    • ISO 4986, ISO 13665, ISO 13664, ISO 10893, ISO 23278

    In addition, the experts in our Magnetic Particle Inspection (MPI) Laboratory also provide a variety of custom services as your needs and requirements. Let's discuss the custom services with our experts for free.

    Instruments and data

    Magnetic Particle Inspection (MPI)
    Magnetic Particle Inspection

    Note: this service is for Research Use Only and Not intended for clinical use.

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    T,C& A LAB is an independent lab providing quality or custom testing, characterization and analysis of a variety of materials. Our engaged experts are ready to help you.

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