Servomotors: More for Less

The hard-working servomotor is being asked to do ever more these days, and it’s stepping up to the challenge in a lot of different ways.

The challenge isn’t new; more power, more torque, in a smaller package for less cost. And that’s exactly what’s been happening. Servomotor manufacturers are indeed increasing motor torque density while managing to decrease motor size.

A big reason why this has been possible is the use of high-powered rare-earth magnetic materials, such as neodymium-iron-boron magnets, according to Dan Jones, a seasoned motor design veteran and President of Incremotion Associates, a California-based engineering design and marketing firm. Along with more powerful magnetic materials are some changes in servomotor design. For example, “instead of putting magnets on the surface of the rotor we’re putting them inside the rotor structure. The reason is that we can develop a reluctance torque to vectorially add to the normal permanent magnet torque, which might mean an increase of 30 to 40%” says Jones.

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