Hot formed Co5Sm to produce radially oriented motor magnets

Permanent magnets have been used for several years in D.C. Motor Applications. The lack of high coercive force with high remanence has required magnets of large volumes to be used. With the advent of the high coercive force cobalt rare earth materials, it is now possible to use very thin magnets for motor applications. The purpose of this investigation was to produce radially oriented Co5Sm arc magnets having thickness as low as 0.13 cm and subtended angles greater than 60° by using a hot forming technique. Various fixturing and hot forming conditions were studied. The results of this work show that radially oriented arcs could be produced with subtended angles as large as 117° and circumferential lengths of 10.5 cm. Additional data indicates that no serious degradation in alignment or magnetic quality was encountered when bending the material slowly at temperatures above 1100°C.