2.3.1 Magnetic field camera for fast - high resolution inline magnet inspection

16. GMA/ITG-Fachtagung Sensoren und Messsysteme 2012
2012-05-22 - 2012-05-23
Nürnberg, Germany
2.3 Magnetsensoren
K. Vervaeke - MagCam NV, Leuven (Belgien)
212 - 219


Fast and accurate quality inspection of permanent magnets is increasingly important in development, production and quality control of ever more accurate and reliable sensors as widely used in automotive applications, more efficient electric drives for e.g. electric vehicles, new medical devices, consumer electronics and many other magnet applications. Furthermore, in many high-end applications a 100% magnet quality control is desired, but not feasible. Also in sensor R&D there is a need for fast and advanced magnet characterization tools for developing nextgeneration sensor concepts and assemblies.
Different magnet types and applications require different parameters to be measured and compared to supplier spec sheets for quality control. For uniaxial magnets, the magnetization vector and its deviation angle are mostly important, while for multipole magnets the pole uniformity, north-south pole symmetry and deviations in pole segment angles are quality-defining parameters. Also field homogeneity and material defects, as well as magnetization defects are important in many applications. Traditional magnetic measurement techniques are not capable of measuring all of these magnet characteristics in an economic way if at all. They have limited capabilities when it comes to their applicability for today’s high demands in magnet quality control, either because they only measure one particular magnet property, are not suited for small magnets, have limited speed or are not suitable for automation (e.g. are not digital) or a combination of the above.
Driven by a clear industrial need for advanced inspection equipment for permanent magnets as outlined above, we recently reported on a new magnetic measurement technology, called a ‘magnetic field camera’ or ‘MagCam’, a powerful and unique measurement platform for fast and accurate live inspection of both uniaxial and multipole permanent magnets. Its applications include manual and automated magnet inspection and characterization, as well as research and development of magnets and magnetic systems in a wide array of applications involving permanent magnets. This unique measurement instrument offers unprecedented characterization capabilities for various magnet and magnetic assembly properties. For uniaxial magnets the system measures the x,y,z-components of the magnetization vector and directly gives the deviation angle with respect to the geometrical symmetry axis. For multipole magnets an analysis is performed including pole height uniformity, high resolution zero-crossing distance/angle measurements, magnetic asymmetries and more. For magnets where field homogeneity is important, a homogeneity analysis can be performed in real time, identifying field inhomogeneities which are generally due to magnetic or mechanical defects in the magnet.
Further advancements in this technique are reported here, including advanced data analysis software algorithms which are able to extract unprecedented magnet property and quality information from the measured magnetic field maps, as well as the ability to implement the MagCam technique in automated production lines for fast – high resolution inline magnet inspection.