Affiliations: [a] BAM Federal Institute for Material Research and
Testing, Berlin, Germany | Université Laval, Canada | Tohoku University, Japan
Correspondence:
[*]
Corresponding author: Matthias Pelkner, BAM Federal Institute
for Material Research and Testing, Unter den Eichen 87, Berlin 12205, Germany.
E-mail: matthias.pelkner@bam.de
Abstract: Their small size together with a remarkable field sensitivity are
the most prominent features of present-day GMR sensors paving the way for
various applications in automated non-destructive testing (NDT). This work
presents a prototype for fast and automated magnetic testing of roller
bearings. A local magnetization unit excites the magnetic field inside the
bearing. As a result of a design study and the following wafer fabrication the
probe was equipped with NDT-adapted GMR sensor arrays in which 48 elements
measures the field response. The detection of artificial and 40 μm deep
defects could be resolved with a SNR better than 20 dB. In addition, we report
of first results of a POD (Probability of Detection) analysis using GMR sensors
to investigate bearings with EDM (electronic discharge machining) notches
having depths down to 10 μm. Finally, we estimate successfully the depth of
a 57 μm notch from the measured data.
