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Reducing Measurement Error in Wet Magnetic Particle Inspection of Metal Castings

This webinar covers measurement variability due to surface roughness, geometry, and human operators in wet magnetic particle inspection (MPI) of metal castings.

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This webinar covers measurement variability due to surface roughness, geometry, and human operators in wet magnetic particle inspection (MPI) of metal castings. Steel castings have rougher surfaces than machined parts, which makes this an important factor to investigate because unevenness on the surface causes the particles to collect and may result in false positives or prevent the human operator from finding true defects. An advantage of castings is their complex geometries; however, this geometry creates a variance in the magnetic field strength on the part. If a process is not properly set up to account for the effect of geometry on the magnetic field strength, the discontinuities may not be identified in regions where the magnetic field strength is low. Lastly, a gauge repeatability and reproducibility (R&R) study was performed in three foundries to investigate the human error in wet MPI. The R&R results were reported as the “percent of matches.”

Key takeaways:

  • Understand the effects of surface roughness on the effectiveness of wet MPI
  • Understand the effects of geometry on the magnetic field strength
  • Understand the current percent match gauge R&R results for wet MPI in metal castings


Sharon Lau

Sharon Lau earned her master's degree from Iowa State University in 2019 and is currently pursuing her doctorate at the same university. She worked for Nike Inc. as a Product Test Engineer for over two years and held a summer internship with Bunn as an engineering intern, both focused on ensuring all quality requirements are met for the product launch. Her doctorate work focuses on process improvements in wet MPI where she uses an image-based approach to objectively quantify aspects of the method.

About American Society for Nondestructive Testing

The American Society for Nondestructive Testing, Inc. (ASNT) is the world's largest technical society for nondestructive testing (NDT) professionals. Through our organization and membership, we provide a forum for exchange of NDT technical information; NDT educational materials and programs; and standards and services for the qualification and certification of NDT personnel. ASNT promotes the discipline of NDT as a profession and facilitates NDT research and technology applications. 

 ASNT Mission Statement

ASNT exists to create a safer world by advancing scientific, engineering, and technical knowledge in the field of nondestructive testing.™

 ASNT Strategic Objectives

  1. Increase participation in society’s activities.
  2. Promote an inclusive vision across ASNT’s membership and the NDT community.
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  6. Grow ASNT through partnership with industry, government, professional organizations and educational institutions.
  7. Advocate and provide NDT personnel certification.
  8. Maintain ASNT’s fiscal stability in order to fulfill the society’s mission.
  9. ASNT will identify paths for lifelong education and career development within the NDT profession including theory, application and skills for the practitioner, engineer and researcher.
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Application Notes