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AW20HS Series — 20mm Stepper Motor with Planetary Gearbox
The AW20HS series pairs Apexwell's NEMA 8 (20mm), 1.8° hybrid stepper motor with an M22GXR planetary gearbox, offering motor holding torque from 0.011 N·m to 0.020 N·m and rated output torque up to 0.5 N·m after reduction. With four available gear-train stages and reduction ratios from 3.7:1 to 720:1 on the same 20mm footprint, this is the smallest frame size in Apexwell's stepper-planetary gearmotor platform, built for compact, low-torque positioning where a bare stepper shaft doesn't have the load capacity or backlash control the application needs.
Shared Specifications (all models)
| Parameter | Value |
|---|---|
| Step Angle | 1.8° |
| Lead Wires | 4 (bipolar) |
| Gear Material | Metal (powder metallurgy) |
| Output Bearing | Ball bearings |
| Radial Play of Shaft | ≤0.05 mm |
| Thrust Play of Shaft | ≤0.2 mm |
| Max Radial Load | ≤1.2 kgf |
| Max Shaft Axial Load | ≤0.7 kgf |
| Backlash (no load) | ≤2.5° |
Motor Model Comparison
| Model | Body Length | Phase Current | Phase Resistance | Phase Inductance | Holding Torque | Rotor Inertia | Mass |
|---|---|---|---|---|---|---|---|
| AW20HS30-0504A | 30 mm | 0.5 A | 4.8 Ω | 1.3 mH | 0.011 N·m | 2.1 g·cm² | 0.05 kg |
| AW20HS38-0604A | 38 mm | 0.6 A | 6.5 Ω | 1.7 mH | 0.018 N·m | 3.0 g·cm² | 0.06 kg |
| AW20HS42-0504A | 42 mm | 0.5 A | 5.2 Ω | 1.8 mH | 0.020 N·m | 3.8 g·cm² | 0.09 kg |
M22GXR Planetary Gearbox Specifications
| Parameter | 1-Stage | 2-Stage | 3-Stage | 4-Stage |
|---|---|---|---|---|
| Reduction Ratio | 3.7, 5.2 | 14, 19, 27 | 51, 71, 100, 139 | 189, 264, 369, 516, 720 |
| Gearbox Length (L1) | 24.4 mm | 33 mm | 41.5 mm | 49.8 mm |
| Rated Output Torque | 0.1 N·m | 0.3 N·m | 0.4 N·m | 0.5 N·m |
| Transmission Efficiency | 80% | 70% | 60% | 50% |
| Weight | 46 g | 51 g | 58 g | 65 g |
Momentary torque moment is rated at three times the rated allowable load across all four stages. 12 reduction ratios are available in total (3.7 to 720:1), letting a single motor size be tuned to different speed/torque targets by swapping gear-train stage count alone.
Typical Applications
With reduction ratios up to 720:1 on a 20mm footprint, the AW20HS series fits micro camera and lens focus mechanisms, small medical and lab instrumentation, miniature valve actuation, optical positioning stages, and other space-constrained devices where a directly-driven stepper shaft can't support the radial/axial load or backlash tolerance the mechanism needs.
Why Choose the AW20HS Gearmotor
Twelve reduction ratios across four gear-train stages let one motor selection be tuned across a wide speed/torque window without changing the mounting footprint. The ball-bearing output stage raises radial and axial load capacity well beyond what the bare motor shaft alone can support, and backlash is held to ≤2.5° at no load — important for repeatable micro-positioning. Because the gearbox is factory-fitted and tested as a complete unit, output shaft alignment and gear mesh are verified before the motor ships. Custom shaft configurations and encoder feedback are available on request.
We can customize the electrical parameters of the motor and geometric dimensions such as the motor output shaft size according to customer requirements. Accessories including pulleys, eccentric gearboxes, planetary gearboxes and encoders can also be added. For more products and detailed specifications, please download the product catalog from the Download Center.
