ESF Thüringen - Liste der Vorhaben Förderperiode 2014-2020

Quality control of permanent magnets

Quality control of homogeneity and magnetic field distribution of permanent magnets (dipole and multipole) 


Due to the manufacturing process of permanent magnets inhomogeneities in distribution of the magnetic material and therefore inhomogeneous magnetic fields can occur. These defects are very hard to identify with standard magnetic field measurement instruments as hall-probes or magnetoresistive sensors, due to the evaluation regarding homogeneity of magnetic fields distribution has to be performed over a large area. Standard measurement devices are working in scanning mode over the investigation area. For quality control applications regarding magnetic field distribution, the magneto-optical sensor system, like the cmos-magview, offers a huge advance. It simultanously displays the magnetic field distribution and measures the corresponding magnetic field intensities for areas up to 3 inches in diameter in real time.

 

 

ring-magnet

 

Ringmagnet (recorded with a cmos-magview)

 

rotary-encoder

Therefore magnetic field or material defects can be identified and protocoled at a glance. The magneto-optical sensor creates two-dimensional cuts through the magnetic field at the surface of an object. Consequently it is also possible not just to control specific single permanent magnets, but also magnetic assemblies and their resulting field intensities and distribution, which is one of the most important thing to control if these assemblies interact within the setup. 

When visualizing magnetic fields with magneto-optical systems it is also a significant advantage that the magneto-optical chips are imaging the field distribution and intensity continuously and therefore enabling the option to investigate dynamic magnetic processes as magnetization, remagnetization and demagnetization processes in real time. Strongly related to measurements of single magnets, also multipole permanent magnets can be visualized and measured. Especially in electric motor, electric generator and alternator industries the growing demand for a reliable and decisive quality control system matches perfectly magneto-optical systems‘ capabilities. 

A magneto-optical inspection provides the huge benefit due to their areal imaging feature, which opens an innovative procedure in order to control rotatory encoder´s surface-magnetic field - consuming just a minimum of time and efforts.