Advances in powder metallurgy soft magnetic composite materials for electrical machines

Soft magnetic composite (SMC) materials offer design advantages when compared with steel laminations due to their isotropic nature and the relative ease of producing complex net shaped components by the powder metallurgy production route. Iron loss is low at elevated frequencies as the eddy current loss is a small portion of the total loss. Future designs envisage smaller motors with equivalent or higher output at lower cost. Solutions requiring higher frequency need cost effective materials with low eddy current loss. The magnetic and mechanical properties of materials achieved by surface insulating iron based powder and the effect of lubricant and binder resin are reported. The influence of compacting techniques has been investigated as well as that of curing temperature. Data reported is concentrated to the frequency range of interest to electrical machine designers, that is 50-1000 Hz.