Temperature and demagnetizing fields are well-known factors influencing the magnetization of permanent magnets in electric motors. While temperature and field contribute directly to reversible or irreversible magnetization changes, time-dependent losses, also known as magnetic viscosity, occur after direct demagnetization and over time [1]. The magnetic viscosity parameter Sv, the ratio of direct and time-dependent losses, provides a reliable property that describes the long-term magnetization performance in general use [2]. Unlike traditional methods such as vibrating sample magnetometry (VSM), which require complex sample preparation, a novel test rig enables fast and accurate measurements on real-sized permanent magnets. In addition, advanced measurement setups, including magnetization curves and field scans, provide comprehensive insight into the demagnetization process.

[1] M. Haavisto, S. Tuominen, H. Kankaanpää, and M. Paju; "Time Dependence of Demagnetization and Flux Losses Occurring in Sintered Nd-Fe-B Permanent Magnets"; IEEE Transactions on Magnetics, 2010, vol. 46, no. 9, pp. 3582-3584; doi: 10.1109/TMAG.2010.2047262

[2] T. Kresse, G. Martinek, G. Schneider, and D. Goll; "The Field-Dependent Magnetic Viscosity of FeNdB Permanent Magnets"; Materials, 2024, vol. 17, p. 243; doi: 10.3390/ma17010243 .