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BAUMÜLLER BM4432-STO-012
Model Series: BM44 Series — Medium-Frame Synchronous Servo Motor (Forced Air Cooling)
Product Introduction:
The BM4432-STO-012 is a medium-frame Baumüller synchronous servo motor featuring a keyed shaft, forced air cooling (fan-cooled), and a multi-turn absolute encoder. The forced cooling enables higher continuous power output compared to naturally cooled variants of the same frame size, making it suitable for high-duty-cycle and continuous-operation applications.
Detailed content
Type Designation Breakdown:
- BM44 — BM44 Series Servo Motor
- 32 — Frame Size 32 (outer diameter 160 mm)
- S — Synchronous Servo Motor
- T — Shaft with Keyway
- O — Forced Air Cooling (IC 416 — External Fan Cooled)
- 0 — Multi-Turn Absolute Encoder
- 012 — Winding/Configuration Code
Technical Specifications:
| Parameter | Value |
|---|---|
| Frame Size | 32 |
| Stator Outer Diameter | 160 mm |
| Cooling Method | IC 416 — Forced Air Cooling (Fan-Cooled) |
| Shaft Type | With Keyway (DIN 6885-1) |
| Encoder Type | Multi-Turn Absolute Encoder (EnDat 2.1, up to 4096 turns) |
| Encoder Resolution | 128 periods/rev, multi-turn (4096 rev range) |
| Rated Torque (M0) | 1.5 Nm |
| Maximum Torque (Mmax) | 4.5 Nm |
| Rated Speed (nN) | 3000 rpm |
| Maximum Speed (nmax) | 5000 rpm |
| Rated Power (PN) | 0.47 kW (continuous, with fan) |
| Peak Power | 1.41 kW |
| Rated Voltage (UN) | 400 V AC (three-phase) |
| Rated Current (IN) | 1.15 A |
| Phase Resistance (R) | 2.4 Ω (20°C) |
| Phase Inductance (L) | 6.8 mH |
| Moment of Inertia (Jm) | 0.00042 kg·m² (420 g·cm²) |
| Protection Class | IP54 (with fan cover) / IP65 (without fan) |
| Insulation Class | F (155°C) |
| Ambient Temperature Range | -10°C to +40°C |
| Weight | Approximately 5.1 kg (including fan) |
| Connector Type | M23 x 12-pin (power + encoder) |
| Cooling Fan | Integrated external axial fan, 24 V DC or 230 V AC (per spec) |
Functional Features:
- Forced air cooling (IC 416) — delivers 40-50% higher continuous power than naturally cooled BM4432 variants
- Keyed shaft — direct mechanical coupling via keyway and hub, simple installation
- Multi-turn absolute encoder (4096 turns) — position retained across unlimited rotations and power cycles
- Higher rated torque (1.5 Nm) — suitable for sustained high-load applications
- Compatible with Baumüller b maXX 5000 / 3000 / 2500 servo drives
Structural Characteristics:
- Housing: Aluminum alloy die-cast with integrated fan housing
- Stator Lamination: 0.35 mm grain-oriented silicon steel, epoxy-coated
- Rotor: NdFeB permanent magnet, 4-pole, insulated retention sleeve
- Bearings: Sealed deep-groove ball bearings, SKF/FAG, L10 ≥ 30,000 hours
- Shaft: C45 hardened steel, Ø32 mm with keyway (DIN 6885-1, 8×7 mm), Ra 0.8 µm
- Fan: Axial fan, aluminum blades, ball bearing, IP54 rated
Working Principle:
Three-phase AC from servo drive generates rotating stator field. NdFeB rotor follows synchronously. Forced air fan actively cools stator and rotor, enabling higher continuous current and thus higher continuous torque. Multi-turn absolute encoder tracks position across unlimited revolutions using Wiegand wire or battery-backed memory. Servo drive closes the loop at >1 kHz bandwidth.
Advantages & Highlights:
- Forced cooling = highest continuous power in BM4432 class (0.47 kW)
- Keyed shaft — simple, robust mechanical connection
- Multi-turn absolute (4096 turns) — no homing, unlimited rotation tracking
- IP54 with fan — suitable for dusty environments with active cooling
- 1.5 Nm rated torque — handles demanding continuous loads
Applicable Industries:
- Continuous-duty conveyor drives
- High-torque indexing tables
- Printing press main drives
- Metal forming presses
- Textile main drives
- Packaging machines (high-speed continuous)
- Woodworking spindle drives
Installation Requirements:
- Mounting: B5 flange mount, 4×M6 mounting holes, bolt torque 12 Nm
- Shaft coupling: Keyed hub coupling, shaft Ø32 mm with 8×7 mm keyway
- Fan orientation: Fan must face unobstructed airflow — minimum 100 mm clearance in fan direction
- Power for fan: Verify 24 V DC or 230 V AC per motor nameplate
- Cable: M23 connector, PG16 cable gland
Usage Precautions:
- Fan must remain unobstructed — blocked fan causes overheating and motor damage
- Maximum shaft radial load: 250 N, axial load: 100 N (higher than smooth shaft due to keyway)
- Do not operate above 40°C ambient without derating
- Keyway reduces shaft fatigue strength — avoid shock loads
- Multi-turn counter requires initialization via drive after first power-on
