A New Micro Magnetic Bridge Probe in Magnetic Flux Leakage for Detecting Micro-cracks

  • Erlong LiEmail author
  • Yihua Kang
  • Jian Tang
  • Jianbo Wu


Magnetic flux leakage (MFL) testing has been widely used as an efficient non-destructive testing method to detect damage in ferromagnetic materials. It’s of great importance to improve the testing capability of MFL sensors. In this paper, a micro magnetic bridge method in MFL of high sensitivity is proposed to detect micro-cracks. This method consists of a micro magnetic bridge core and an induction coil. Furthermore, a novel micro magnetic bridge probe (MMBP) of higher spatial resolution is designed and developed with \(10~\upmu \hbox {m}\) width between the two sides of this MMBP in the testing magnetic bridge. The lift-off effect of this new MMBP is studied via finite element method and experimental verification. The results show this MMBP can achieve high sensitivity only when working with a micro-lift-off value. To examine the detecting capability of this MMBP, micro-cracks in magnetic particle inspection sensitivity testing pieces are all inspected, and the lowest depth value is only \(7~\upmu \hbox {m}\). The MMBP in this paper improves the testing capability of MFL to the micrometre scale and can be widely used to detect grinding micro-cracks in bearing rings.


Non-destructive testing (NDT ) Magnetic flux leakage (MFL) Micro-cracks Micro-magnetic bridge probe (MMBP) Magnetic particle inspection (MPI) 


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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhanChina
  2. 2.School of Manufacturing Science and EngineeringSichuan UniversityChengduChina

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