Packing a motor and machining spindle in one unit lets engineers at Weiss GmbH (www.weissgmbh.de/home.php?lang=en), in Germany eliminate couplings, belts, and gearboxes. It also lets them cut back on spindle inertia and increase acceleration and deceleration times. The lack of drive-traverse forces makes the spindles accurate, thanks to smooth, precise spindle motion even at low speeds. The units are compact, lightweight, and have high power densities. Motors can be synchronous or asynchronous, and they can be combined with servodrives or inverters.
On milling spindles, power ranges from 6 to 150 kW, speeds vary from 3,000 to 60,000 rpm, and they can be equipped with ceramic, 100Cr, or CronidurR30 bearings. Turning spindles have torque to 918 Nm and speed to 12,000 rpm.