A high accuracy brushed pancake motor from Printed Motor Works is being used in a new ultraprecise rotary table developed by metrology manufacturer Rotary Precision Instruments.

The motor needed to be extremely smooth-running to deliver the angular precision needed for the inspection of critical components such as turbine rotors. A printed armature motor was determined to be the best choice.

The iron-free armature in the GN9T servo motor produces zero cogging with no torque ripple under load, while the coupling to a strain wave gearbox ensures zero backlash.

The ultracompact motor, which has an internal tachometer to provide speed feedback, also had to have a very low profile to enable it to fit within the rotary table base.

Another important factor was minimising heat losses so as not to impair measurement precision and not to heat up the laboratory environment since the instruments are usually used in temperature controlled QA laboratories. The motor can optionally be cooled with forced air cooling through ports in the side casing.

The rotary table is designed for use in metrology applications such as coordinate measuring machines as well as in the angular calibration of precision instruments such as tilt meters, inclinometers, encoders, indexers, gyroscopes and guidance systems.

GN9T zero torque ripple motor from PMW in rotary table application





PMW Dynamics