Product Description:

The U9M4H is a flat DC servo motor manufactured by Kollmorgen within the ServoDisc Pancake DC Motors series. This frameless unit integrates a high-energy permanent-magnet rotor and a lamination-free disc armature, allowing direct coupling to light rotary stages and pick-and-place heads. Its role in industrial automation is to supply controllable torque and speed in axes where a short axial length and minimal cogging are critical for repeatable positioning.

The motor has a back electromotive force constant of 7.50 V/krpm and a torque constant of 10.15 oz-in/A, providing predictable voltage-to-torque conversion for analog or PWM drives. Motor terminals have a resistance of 0.850 ohms, so the rated continuous current of 8.6 A results in moderate copper loss while supporting the specified operating point. When supplied with 31.9 V, the rotor reaches a rated speed of 3000 rpm and can sustain 81 oz-in of torque at 25 °C. The sustained torque decreases to 72 oz-in at 40 °C as the operating temperature rises. A continuous stall capability of 65 oz-in lets the axis hold static loads without overheating. The design accepts momentary acceleration up to 6000 rpm, extending process throughput during rapid indexing. Its overall mass is 5.3 lb, which helps keep the moving inertia of the host mechanism low.

Cogging torque is 0 oz-in, eliminating detent forces and simplifying fine velocity regulation. The armature inertia is only 0.0058 oz-in-sec², so the drive can reverse direction quickly while supporting responsive control-loop tuning. During transients, the winding can accept a peak current of 72 A, producing up to 727 oz-in of peak torque for short bursts such as press cycles or rapid table starts. Under continuous load at rated conditions, the motor delivers 179 W of mechanical power for mid-range motion tasks such as small conveyor rollers and precision dispensers.