Rare-earth bonded magnet becomes the progenitor of the magnet business
The SAM-D, a bonded magnet made of samarium and cobalt, was developed in 1970 as a rotor magnet for stepping motors used in quartz watches. This rare-earth bonded magnet offered a great deal of shaping flexibly, as well as good dimensional accuracy. This flexibility and accuracy made the magnet most welcome in applications needing compactness and power, for not only were bonded magnets structurally strong, they were less costly than the conventional sintered type. The outstanding workability of the magnet enabled Epson* to produce high-precision rotor magnets in high volume. Moreover, the SAM-D provided essentially equivalent performance to that of platinum-cobalt magnets, yet at one-twentieth the material cost (as a ratio of volume). Thus these magnets were a significant factor in helping Epson reduce the cost of quartz watches.
Direct sales of SAM-D magnets began later, in 1976. Despite their small size, SAM-D magnets provided both outstanding magnetism and workability, features that earned them uses in applications outside quartz watches in small acoustic instruments and office equipment, for example. In addition, competition among quartz watchmakers to make their timepieces smaller and thinner led, several years later, to the development of the SAM-DH, a magnet that offered even higher performance than the SAM-D.
*Then known as Suwa Seikosha Co., Ltd.