Magnetic Particle Inspection

Magnetic particle testing (MT) utilizes one or more magnetic fields to detect surface and near-surface irregularities within ferromagnetic materials. These magnetic fields can be generated through either a permanent magnet or an electromagnet. In the case of an electromagnet, the field is active only during the application of current. As the magnetic field encounters a transverse discontinuity, it results in the creation of a magnetic flux leakage field, as depicted in the accompanying diagram (notice the alteration in magnetic polarity). Since magnetic flux lines have limited travel distance in air, finely colored ferromagnetic particles are delicately spread onto the part’s surface. The outcome of this procedure is that these particles become attracted to the flux leakage field generated by the discontinuity, leading to a discernible indication on the part’s surface.

These magnetic particles can exist in either a dry powder form or be suspended within a liquid solution, often infused with a visible dye or a fluorescent dye that emits fluorescence under a 365 nm ultraviolet wavelength. 

Magnetic particle inspection methods

Rely on the Expertise of NDT Professionals at ND Testing, Inc.

Magnetic particle inspection is flexible, with wet and dry methods available based on the specific application. In both techniques, an electric charge is applied to the product to establish a magnetic field. Subsequently, ferrous iron particles are introduced to the component in either a dry or wet suspension.

When a crack or defect exists, these particles will gravitate toward the imperfection, amassing around the leakage to form a visible ‘indication.’ This indication is then scrutinized to ascertain the traits and root cause of the flaw. The outcomes enable our Dedicated Experts to comprehend the nature and extent of any discontinuities present on the part’s surface or beneath it. 

The ND Testing, Inc. advantage in MPI testing

Through careful analysis of the nature, location, and extent of an indication, our extensively trained and skilled inspectors adeptly identify the origins and causes of both surface and near-surface discontinuities. ND Testing, Inc. operates fully equipped non-destructive testing (NDT) and magnetic particle inspection laboratories that feature state-of-the-art equipment capable of conducting meticulous inspections on a wide range of ferrous materials, components, and assemblies.
To learn more about our magnetic particle testing or to request a quote, kindly reach out to us today. Despite the availability of advanced measurement and imaging tools, visual inspection (or visual testing) remains a valuable and pertinent method across various applications. Our Dedicated Experts are adept at detecting defects, irregularities, and distinctive patterns in materials, equipment, and structures, assisting you in upholding quality and consistency in your products and processes.
Often employed in conjunction with our non-destructive testing services, visual inspection instills added assurance that your products are devoid of flaws and discontinuities. Employing the industry’s most respected standards and methodologies, we meticulously scrutinize your products, irrespective of size or quantity.