“After extensive tests, we decided on the brushless DC-servomotor from the FAULHABER line”, Krawez continues. “The motor of the 4490 … BS series satisfies our requirements in every regard; furthermore, we have already had good experiences with the drive specialists from Schönaich.” Motor The 2-pole servomotor is a three-phase external rotor motor with wide speed and torque range. The integrated linear Hall sensors enable the required low speeds. Thanks to its ironless design, the motor oper- ates cogging-free, with an absolutely linear relation- ship between load and speed, current and torque as well as voltage and speed and offers a highly sensitive current/torque behaviour. These motor characteristics are reflected in the measurement results. Viscosities can be determined with an accuracy of up to 0.5 cmg in a measurement range from 0 to 2,500 cmg. Long-lasting and compact Other important requirements on the drive were longevity and compact dimensions. After all, the motor needs to function reliably over the entire life- time of the device as well as be easy to integrate. The brushless servomotor convinced in both regards. Due to the electronic commutation, its service life depends mainly on that of the motor bearings. Here, highly precise pre-loaded ball bearings are used which have proven their reliability in a wide range of application areas. At the same time, the very compact dimensions of the 282 watt motor – measuring just 44 mm in dia- meter and 90 mm in length – were a perfect fit in the ViscoQuick’s limited installation space, as the measur- ing device itself is designed to be very space-saving. “We were, therefore, very happy that FAULHABER also has a suitable, space-saving controller in their product line with the MCBL 3006”, says a pleased Krawez. With its dimensions of 58 mm by 65 mm, the footprint of the controller, which is perfectly matched to the motor, is the size of a credit card; in terms of height, it measures only 27 mm. It communicates with the higher-level control system of the viscometer via an RS232 interface; actuation is also possible via CANopen. The combination of brushless DC-servomotor and matched controller has proven effective in the Visco- Quick. Brabender also uses the same solution in other measuring instruments, such as in the Amylograph-E, which supplies a reliable and reproducible picture of enzyme activity (alpha-amylase) in flours and grains. Here, too, changes in torque are measured and are automatically recorded in an amylogram. brabender.com faulhaber.com FAULHABER motion 23