Product Description:

The M21NRFA-LNN-NS-04 is a two-phase stepper motor produced by Pacific Scientific for the POWERMAX II M Motors series. It converts pulse trains from a drive into incremental rotary motion for indexers, pick-and-place axes, and compact conveyor stations. Its NEMA mounting interface and compact mechanical layout allow quick integration into small automation frames. The model is supplied without a feedback encoder, so it is intended for open-loop positioning systems where repeatability is established electrically rather than through a sensor. This makes it suitable for applications that rely on commanded step counts instead of closed-loop correction.

Holding torque of 1.00 Nm is the static load the shaft can resist when the coils are energized. Detent torque of 0.066 Nm is the residual mechanical torque present with no current applied, and it shows how much disturbance is needed to shift the rotor when power is off. Each command pulse advances the shaft by 1.8 degrees, and with 200 steps per revolution the motor delivers fine incremental motion. Step accuracy remains within ± 1.5%, which helps limit cumulative positioning error across multiple moves. This step format is well suited to feeders, light gantries, and other small positioning mechanisms that require uniform incremental movement.

Rotor inertia of 0.0017 oz-in-s² supports quick acceleration in the single-stack construction. The shaft has a diameter of 0.2500 in, which simplifies coupling to pulleys or flexible hubs. The motor operates between -20 °C and +40 °C, and it uses a thermal resistance of 5.5 °C/W with Class B insulation rated to 130 °C. Front bearings accept up to 20 lb of radial load and 13 lb of axial load. The motor uses winding type A, has insulation resistance of 100 megohms with a 340 Vdc dielectric rating, and includes eight flying leads for a regular lead-wire connection. Its NEMA 23 frame keeps overall dimensions consistent with common drive packages.