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Compact mover delivers flexibility, extends life

Article-Compact mover delivers flexibility, extends life

Compact mover delivers flexibility, extends life

Arguably, the lowly shaft coupling is the "Achilles heel" of motion system design. Used to fasten a motor shaft to a drive screw, couplings add compliance to actuator systems. If misaligned, couplings reduce bearing life, and decrease efficiency. A hollow-shaft stepper motor driving a ballscrew through its center eliminates couplings, providing a more compact, reliable actuator, while improving efficiency over leadscrew designs.

"While more expensive, ballscrews provide a wider range of design options, longer life, and higher efficiency than leadscrews," says EADmotors Project Engineer Rob Cinq-Mars. The motor consists of a magnet assembly on a hollow shaft. The hollow front shaft extension is tapped internally to mate with common threaded ball nuts. When the ballscrew is kept from rotating, it actuates linearly through the hollow shaft of the stepping motor. To match all types of unipolar and bipolar drives, a full spectrum of windings is available.

Cinq-Mars reminds engineers to keep in mind that the ball nut must be less than 1.5 inch in diameter, the screw and load must be fixed to prevent rotation, and the design must maintain enough clearance for the ballscrew behind the motor. "Engineers benefit because it's so easy to change the screw out," explains Cinq-Mars. A wide assortment of mounting hubs lets engineers change the screw's pitch and alter the speed, exerted force, or positioning resolution without changing the package size.

Additional Details...Contact Karen Russo, 1 Progress Dr., Dover, NH 03820; Tel: (603)742-3330; FAX: (603) 742-9080;

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