Product Description:

The U9M4 servo motor from Kollmorgen belongs to the ServoDisc Pancake DC Motors series. With its ironless disc armature and 4.37 in outside diameter, the unit keeps its axial length short while providing rapid torque response for positioning tables, pick-and-place heads, or low-inertia coiling stations in industrial automation. Kollmorgen supplies this motor as a frameless torque source that integrates into custom housings. Its flat profile reduces stack height in machines where space along the shaft axis is limited.

At a continuous stall rating of 41 oz-in, the motor can hold load torque without thermal overload when airflow is available. Under rated conditions at 25 °C, the continuous output increases to 51 oz-in, while an ambient temperature of 40 °C reduces it to 46 oz-in. The design reaches a rated shaft speed of 3000 rpm when 24.1 V is applied and 8.7 A flows through the windings; that current limit establishes the continuous operating point. The copper path presents 0.850 ohm of terminal resistance, so the applied voltage and current produce a mechanical output of 113 W. A torque constant of 6.56 oz-in/A links shaft torque to armature current. A back EMF constant of 4.85 V/krpm establishes the speed-to-voltage relationship across the recommended operating range.

For transient moves, the motor delivers a peak torque of 469 oz-in when the drive supplies 72 A. Shaft velocity may be commanded up to 6000 rpm without commutator damage, providing a two-to-one speed margin over the continuous operating point. The rotor has a low polar inertia of 0.0056 oz-in-s², which minimizes stored energy and allows rapid velocity changes with modest servo gains. The motor has an overall mass of 4.5 lb, helping to keep moving weight low on gantry axes or robotic wrists.