CNC specialist NUM, which has a UK subsidiary in Coventry (
www.num.com), has expanded its portfolio of motors for machine tool applications by launching a range of high-performance brushless torque motors.
Featuring “optimised magnetics”, the new TMX-series direct-drive motors have a very low cogging torque — said to be almost half that of competitors’ motors.
They have been designed for applications that demand very smooth and accurate rotation, especially at low speeds; typical uses include direct-drive machine tools, rotary tables and radial positioning units.
Massimiliano Menegotto, general manager of NUM’s main manufacturing plant in Milan (Italy), said: “A growing number of our customers request customised motors, and they prefer to deal with a single supplier for all their CNC machine tool requirements.
"We have developed the TMX series of torque motors specifically to address these needs.”
NUM is initially launching two TMX-series frameless torque motors — with stator diameters of 140mm and 291mm — and says it intends to ‘grow’ the range in the future.
The motors’ hollow shaft rotors use high-flux-density neodymium-iron-boron magnets and give ample internal space for through-motor wiring or mechanical parts.
The stator windings are fully protected against over-temperature conditions; they are encapsulated within a thermally optimised enclosure that offers a choice of air-cooled or water-cooled configurations.
Like all direct-drive motors, the TMX-series units can provide continuous torque (even when stalled) and are designed for direct attachment to the load, thereby obviating the need for gearboxes or shaft couplings and providing highly accurate backlash-free rotary transmission.
TMX-series motors are available with a choice of stator and rotor lengths to best suit the application. For example, a 140mm-diameter motor with an active length of 70mm can produce a peak torque of about 82Nm at speeds up to 1,500rev/min, and a continuous (stall) torque of about 50Nm.
The motors can be driven by most industry-standard servo drives, including NUM’s MDLU3 and MDLUX drives, which form part of the company’s latest-generation Flexium+ CNC platform.