It's interesting to learn how magnetic efficiencies can lead to optimized motor performance. What about the frame/bearings? It'd be interesting to read more about the materials used to handle the small, high-speed bearing surfaces, and how heat is dissipated from these support structures.
I understand that a combination of solid film lubricants like MoS2 that sustain the bearing at low speeds and then transition to an air lubrication mode are quite effective at high speeds in reducing bearing losses. Bearing systems like these can give very long life as long as the air supply is clean and abundant.
Are any of the motors making use of air lubrication?
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