Compression-molded magnets

Traditionally, resin-bonded permanent magnets have mainly been prepared by the compression molding method, or by the injecrion molding method. In the compression molding method, epoxy resins have been used. 

Compression molding realizes high densities of magnetic powders. In laboratory-scale experiments, it is possible to prepare magnets with more than 80 vol.% magnetic powder. 

The relationship between the magnetic flux loss and the volume fraction of voids in injection/compression-molding bonded magnets after treatment under the same conditions is represented in fig. 37 (Mino and Hirosawa 1999). It is clear that the magnetic flux losses proportionally decrease with increasing volume fraction of voids. 

The polymers included in this study are bisphenol-A polycarbonate (Bis-A PC), polyesteicarbonates (PEC), whose structures are defined in Figure 1, phenolphthalein bisphenol-A copolycarbonate, and polysulfone. All samples were compression molded and physically aged as described elsewhere, with the exception of those for the Fourier transform infrared (FTIR) measurements and solid state variable temperature nuclear magnetic resonance (VTNMR)... 

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