• 2 phase, NEMA8 frame size
• 40 mm long
• 0.4 A phase current
• 0.027 N.m holding torque
• 4 mm shaft size
• Built with high quality materials.High precision, low motor heating, and low vibration。
The 20J1840-404 is a NEMA8 (20 mm) 2-phase micro stepper motor, 40 mm long, rated 0.027 N·m at 0.4 A with a 4 mm shaft. It is designed for the very compact mechanisms found in laboratory instruments and precision positioning systems.
The 0.027 N·m rating safely moves optics adjusters, particle positioning fixtures and minute specimen stages. The low 0.4 A current is easily supplied by compact driver boards.
Optical and laboratory instruments that position sensors, lenses or small fixtures favor a micro motor with low vibration and negligible heat. Open-loop stepping gives repeatable movement without encoder complexity.
The modest current permits simple driver circuitry and small supplies, easing portable and battery-operated instrument integration.
The 4 mm shaft and NEMA8 interface fit compact micro-coupling hardware and small mounting plates.
| Model | 20J1840-404 |
| Phase | 2 |
| Step Angle（deg） | 1.8 |
| Holding Torque(N·m) | 0.027 |
| Rated Current（A） | 0.4 |
| Phase Resistance(ohm) | 12 |
| Phase Inductance（mH） | 4 |
| Detent Torque（mN·m） | 2 |
| Rotor inertia（g·cm²） | 4.5 |
| Insulation Class | B |
| Number of Leads | 4 |
| Weight（kg） | 0.16 |
| Length（mm） | 40 |
| Matched Drive | 2DM522-RC/EC2DM415 |
| Frame Size（NEMA） | 8 |
| Shaft Diameter（mm） | 4 |
| Frame Size(mm) | 20 |
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