At the 2009 (30th) Superior Energy-Saving Machine Awards sponsored by the Japan Machinery Federation, Okuma's PREX motor received the Japan Machinery Federation President's Award for a permanent magnet interpolation reluctance motor with multilayer slit structure.
The Superior Energy-Saving Machine Awards are given to individuals, companies, or other organizations that develop and commercialize machinery with superior energy-saving characteristics that contribute to the advancement of efficient energy usage. The awards aim to promote the development and spread of superior energy-saving machinery.

Product awarded - PREX motor (permanent magnet interpolation reluctance motor with a multilayer slit structure)
PREX motors are built-in type reluctance motors incorporated in the many spindles used in machine tools. Numerous slits in the rotor make generation of reluctance power more efficient. This unique rotor structure has a small amount of interpolated permanent magnets to increase performance. The PREX motor is more efficient than the induction motors that were the main power source of spindles in the past, and high torque in the turning ranges used in most machining raises system efficiency at rated speeds 4-9%. PREX motors are also compact, with low mass in the rotating section that reduces inertial mass 47%. This makes acceleration and deceleration highly responsive. The combination of all these features reduces energy consumption by 5-13%.
Compared with IPM motors, which have similar interpolated magnets, there is less efficiency loss from reverse field currents at high rotation speeds. And since fewer magnets are employed, the use of rare earth magnets, a scarce resource, can also be decreased.
Machines equipped with the PREX motor are CNC lathes, the Space Turn EX series, and MULTUS series multitasking machines.