Now the practice is looked upon as a way to save energy.

One indication of the trend is the recent naming of a gear-driven spindle design by the Japan Machinery Federation as the “best energy-saving technology.” The design comes from Kitamura Machinery, a Wheeling, Ill., maker of machining centers. It lets Kitamura use smaller motors than on the direct-drive or integral- spindle units common in the industry today, thus cutting energy consumption between 40 and 50%. Ancillary benefits include higher precision and the ability to step from low rpm, heavy-duty machining to high-speed, high-productivity cutting, Kitamura says.