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[September 2004]
Ceramic Shaft at Heart of Tiny Motor
The new DC motor RE 8 from maxon motor uk (Finchampstead, Berks, England) is the company's response to the world-wide demand for smaller and smaller drives. Only 8mm in diameter, 16mm long and weighing less than 4g, it is capable of delivering a nominal 0.5W.
The motor shaft is as thin as pencil lead at only 0.8mm in diameter and turns in two sleeve bearings. The shaft is ceramic and in some ways superior to a steel one as its electrical insulating properties offer advantages in terms of compactness. Precious metal brushes also ensure constant and low contact resistance between brushes and commutator, even after prolonged standstill.
The heart of the motor is the world-wide patented ironless rotor. The lightweight rotor has very specific advantages, says maxon, such as particularly low mass inertia and very fast acceleration. There is no magnetic detent at all and minimal electromagnetic interference.
Together with a neodymium permanent magnet, maxon's ironless winding is claimed to be much more efficient than other motor designs, making this drive particularly suitable for network-independent applications such as lasers, levelling equipment or insulin pumps. Planetary gearheads can also be attached for certain applications where the given motor speed is too high and torque too low. The modular system can also provide a sensor for detecting speed and position.
www.maxonmotor.co.uk
ENDS