Magnetic field cameras inspect permanent magnets

Paul Boughton

Fast and accurate quality inspection of permanent magnets is increasingly important in development, production and quality control of ever more accurate and reliable sensors. These are widely used in automotive applications, more efficient electric drives for electric vehicles, new medical devices, consumer electronics and many other magnet applications.

Furthermore, in many high-end applications a 100 per cent magnet quality control is desired, but not feasible with classical magnetic measurement equipment. Also in sensor R&D there is a need for fast and advanced magnet characterisation tools for developing next-generation sensor concepts and assemblies.

Different magnet types and applications require different parameters to be measured and compared with supplier spec sheets for quality control. For uniaxial magnets, the magnetisation 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 magnetisation 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 (eg, they are not digital) or a combination of the above.

MAGCAM developed the magnetic field camera technology for inspection of permanent magnets, based on a high resolution and high speed quantitative 2D mapping of the magnetic field distribution of a magnet, using a patented sensor chip with an integrated 2D array of microscopic Hall sensors with a sensitive area of 12.8mm x 12.8mm, with 0.1mm pixel resolution, equaling 128x128 = 16384 measurement points. A full resolution frame is recorded in less than one second. When combined with a mechanical scan system, larger surfaces can also be measured at high speeds.

Also permanent magnet rotors can be inspected using Magcam’s Rotor Inspector configuration, whereby the radial magnetic field distribution is recorded over the full rotor surface with high spatial resolution.

MagScope is MAGCAM’s advanced data analysis software for measuring and analysing magnetic field distributions in real time. MagScope is designed to extract as much in-formation as possible from the measurement data. A wide variety of field distribution types can be analyzed using color plots, surface plots, line plots of cross-sections, statistical analysis of field distributions, automatic detection of zero crossings and multipole segment sizes, measurements of distances and angles between magnetic field features. These analyses can be performed both in Cartesian and cylindrical coordinate systems. Also a Python scripting module is built-in for, for example, automated pass/fail analysis, automated data logging and more.

It is important to note is that MAGCAM offers service measurements, aside from selling its magnetic field camera systems. These service measurements are a cost-efficient alternative to the purchase of a MAGCAM measurement system, or a perfect way to quickly solve problems concerning magnet quality, by having the MAGCAM experts (with years of experience) measuring and analysing your magnets using the world's most powerful magnet inspection system, whereby their year-long expertise in advanced magnet analysis is at your disposal. Service measurements are also a perfect introductory stage in the initial evaluation of the MAGCAM inspection platform, when you are considering the purchase of a system.

MAGCAM invites you to contact us in order to discuss how our technology can be used in your applications. MAGCAM’s customers include sensor manufacturers, motor/generator constructors, medical and biotech companies, consumer electronics producers, high-end speaker OEM’s, research labs, magnet producers and more.

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