Improving the distribution of magnetic properties in rare earth-cobalt magnets by the use of selective thermal stabilization

Typical production rare earth-cobalt permanent magnets have a nominal variation of ±5 for remanence and ±10% for energy product. A technique is described For improving the distribution of these properties using stabilizing temperatures which are a function of the measured properties of the as-magnetized magnet and its operating point. It is possible to achieve a 90% yield at a ±1% tolerance band of remanence. Data are given for two lots of production magnets, to which this technique has been applied.