Robot stepper 08H20

for automation

Product overview
The Size 8 (20 mm) 2-phase hybrid rotary stepper motor, 8H series (examples: 8H2028, 8H2038), delivers up to 0.02 N·m holding torque. Encoder, 22 mm-frame planetary gearbox and power-off brake options are available for compact automation, instrumentation and robotics applications.

Key specifications — general
Step angle: 1.8° ±5%
Insulation class: B
Duty type: S1
Dielectric strength: 500 VAC / 1 kHz / 1 mA / 1 s
Insulation resistance: 100 MΩ / 500 VDC
Permissible radial load (from mounting surface): 5 mm = 15 N; 10 mm = 12 N; 15 mm = 8 N; 20 mm = 6 N

Type data (examples)
Type | Current (A RMS) | Resistance (Ω) | Inductance (mH) | Holding torque (N·m) | Rotor inertia (g·cm²) | Length (mm) | Mass (g)
8H2028 | 0.5 | 5.1 | 1.5 | 0.014 | 2.7 | 27 | 60
8H2038 | 0.5 | 8.8 | 2.7 | 0.02 | 3.3 | 38.2 | 80

Materials

• End bell: Aluminum alloy
• Bearing: Deep groove ball bearing
• Magnet: Sintered NdFeB
• Shaft: Stainless steel
• Wiring: UL 3265, 28 AWG

Dimensions & drawings
Dimensional drawings and product images for Size 8 (20 mm), including model 8H2028, are available for integration and panel design reference.

Torque performance curves
Torque/speed curves available for models 8H2028-050 and 8H2038-050 to assist motor selection and controller tuning.

Options — Encoder
Available resolutions (CPR): 100, 108, 120, 125, 128, 200, 250, 256, 300, 360, 400, 500, 512, 720, 800, 1000
Outputs: single-ended codes 0–15; differential codes A–P.

Options — 22 mm planetary gearbox
Housing material: Metal
No-load backlash: 1°
Bearing type: Sleeve bearing
Ratio | Rated torque (N·m) | Limit torque (N·m) | Stages | Efficiency (%) | Length (mm) | Mass (g)
4 | 0.03 | 0.09 | 1 | 81 | 16.3 | 29.1
15 | 0.05 | 0.15 | 2 | 66 | 16.3 | 30.1
20 | 0.05 | 0.15 | 2 | 66 | 16.3 | 30.1
107 | 0.1 | 0.3 | 3 | 53 | 19.5 | 36

Options — Power-off brake (Size 8)
Rated voltage: DC 24 V ±5%
Resistance: 55 Ω ±10%
Power: 9.6 W
Hold torque: >0.06 N·m
Insulation: class B; Insulation resistance: >100 MΩ (DC 500 V)
Dielectric strength: AC 1000 V / 1 s
Retraction / release time: 50 ms / 50 ms
Gyration gap: 1°; Emergency brake cycles: 200; Lifetime: 500,000 cycles; Noise level: <60 dB

Features / Technical summary

• Product family: Size 8 (20 mm) 2-phase hybrid rotary stepper motor — 8H series
• Step angle: 1.8° ±5%
• Typical current: 0.5 A (RMS)
• Holding torque: up to 0.02 N·m (model dependent)
• Lengths / masses: 27 mm / 60 g (8H2028); 38.2 mm / 80 g (8H2038)
• Materials: aluminum end bell, stainless steel shaft, sintered NdFeB magnet
• Available options: encoder, 22 mm planetary gearbox, power-off brake