For more than a decade, Heidenhain group member ETEL has been producing frameless torque motors with high continuous flux density (in the magnetic gap) for powering thousands of machine tools around the world. An increasing number of manufacturers are keen to use direct-drive torque motors to control axis motions precisely, as their advantages over conventional drives with gearbox or toothed-belt transmissions are well known.

What may not be so obvious is that effective heat dissipation by liquid cooling increases torque motor performance, and can even double it. Until now, cooling management was mainly the responsibility of the customer, who had to design a machine structure precisely to accommodate the motor and ensure water tightness, especially against the ingress of coolant flowing close by.

With the introduction of the cooling jacket option on all low-cogging ETEL TMB+ motors, which in any case are thermally efficient, Heidenhain is providing a solution that removes the burden of both cooling and water tightness from the machine designer. At the same time, it leaves room for different machine layouts and material selections, which can lead to cost reductions. Design flexibility is assisted further by the jacket being available with either radial or axial water inlet/outlet.

ETEL claims to be unique on the market in that more than 60 of its motor sizes are equipped with a cooling jacket. Optimised for ease of mounting, the jacket consists of a mounted metal enclosure that ensures water tightness and high motor performance compared with conventional mounting relying on open cooling, says the company

Customers may decide whether or not to have the motor delivered with the cooling jacket already fitted. As the motor inside is a standard TMB+ product, all variants of the products' windings, cables, sensors and bridge are compatible.