The comparison of the pull-out torque of permanent magnet couplings predicted theoretically with experimental measurements

The accurate prediction of the pull-out torque for new permanent-magnet-coupling designs can only be made by extrapolation from earlier designs. The pull-out torque predicted by three methods has been calculated from measurements of the magnitude of flux density patterns and the dimensions of the couplings. These are the methods of C.J. Fellows (CME, June 1979), W. Baran and M. Knorr (2nd Int. Workshop on Rare-Earth Cobalt Permanent Magnets and Their Applic., 1976), and Y. Tamera et al. (2nd Int. Workshop on Rare-Earth Cobalt Permanent Magnets and Their Applic., 1976). These theoretical predictions are compared to the experimental pull-out torque. The use of the formulation due to Baran and Knorr is recommended if a manufacturer wishes to design a permanent-magnet coupling with a torque range below 1/3 N-m