FANUC A06B-0205-B200 AC Servo Motor
Alpha iF 2/5000 with Keyed Shaft
Key Differentiator: Mechanical Power Transmission
The FANUC A06B-0205-B200 AC servo motor from the Alpha iF 2/5000 series features the same proven motor core as the broader B-series family, but is engineered with a φ10 mm straight shaft incorporating a keyway. This mechanical interlock provides positive torque transmission, eliminating reliance on friction alone for rotational force transfer.
This motor delivers rated power of 0.75 kW (1.0 HP) at 4,000 RPM with maximum speed reaching 5,000 RPM. It generates stall torque of 2.0 Nm and peak torque up to 8.3 Nm when required. Weighing just 4.3 kg, it maintains lightweight construction without compromising performance. The integrated FANUC Alpha iA1000 pulse coder provides the high-resolution position feedback essential for closed-loop accuracy in CNC applications.
Technical Specifications
| Rated Output |
0.75 kW / 1.0 HP |
| Rated Speed |
4,000 RPM |
| Maximum Speed |
5,000 RPM |
| Stall Torque |
2.0 Nm |
| Maximum Torque |
8.3 Nm |
| Stall Current |
3.5 A (rms) |
| Torque Constant |
0.57 Nm/A (rms) |
| Back EMF Constant |
20 V (rms) / 1,000 min⁻¹ |
| Armature Resistance |
1.1 Ω |
| Rotor Inertia |
0.000526 kg*m² |
| Mechanical Time Constant |
0.005 s |
| Thermal Time Constant |
20 min |
| Static Friction |
0.2 Nm |
| Shaft Type |
Straight with Keyway, φ10 mm |
| Encoder |
Alpha iA1000 Pulse Coder |
| Weight |
4.3 kg |
| Holding Brake |
Not included |
Keyway Advantage in Industrial Applications
The keyed shaft configuration provides critical benefits in applications requiring positive mechanical locking under dynamic or reversing torque conditions. Unlike smooth shafts that depend solely on coupling clamping force, the keyway prevents relative rotation between shaft and load, ensuring reliable torque transmission in demanding environments.
This design is particularly valuable for feed axis drives on milling machines, rotary tables, index heads, and any application where bidirectional loads are common. The Alpha iA1000 pulse coder communicates via FANUC's FSSB (FANUC Serial Servo Bus) when connected to compatible αi series servo amplifiers, enabling precise multi-axis CNC control.
Typical Applications
- CNC machining centers and turning centers - axis drives requiring zero backlash and slip tolerance
- Rotary table and indexing axis drives - applications benefiting from keyed connection under cutting load
- Automated assembly systems and robotic end-effectors - where repeatable positioning under varying load is essential
- Direct coupling to ballscrews or gearboxes - simplifying coupling design and improving torque transfer reliability
Replacement Considerations
When replacing motors in the A06B-0205 family, verify shaft configuration to ensure compatibility. The B100 (plain straight shaft), B200 (straight with keyway), and B000 (taper shaft) are electrically identical but require different couplings. Installing an incorrect shaft type can compromise torque transmission and system performance.
Frequently Asked Questions
What is the difference between the A06B-0205-B200 and the B100 or B000 variants?
The motor's electrical performance is identical across all three variants. The distinction is purely mechanical: B000 uses a taper shaft, B100 has a plain straight shaft (φ10 mm), and B200 features a straight shaft with keyway (φ10 mm). Selection depends on your coupling or load hub design.
Does the A06B-0205-B200 include a holding brake?
No, this variant does not include an integrated brake. For vertical axes or applications requiring power-off position holding, select a brake-equipped variant identified by a "4" in the third digit of the suffix (e.g., B4XX series).
Which FANUC servo amplifier is compatible with this motor?
The A06B-0205-B200 is designed for use with FANUC αi series servo amplifiers. The Alpha iA1000 pulse coder communicates natively with FANUC CNC systems via FSSB. Verify amplifier axis card rating against the motor's stall current of 3.5 A (rms) and maximum drive current of 20 A (peak).
Can this motor be used as a direct drop-in replacement for a B200 from an older Alpha iS series motor?
While Alpha iF and Alpha iS series share similar physical dimensions, encoder compatibility and amplifier pairing differ between generations. Before cross-series replacement, confirm that the replacement amplifier supports the Alpha iA1000 encoder and that motor parameters in the CNC match the iF 2/5000 profile to prevent instability or alarm faults.
What are the most common failure points on this motor, and are they repairable?
The Alpha iA1000 pulse coder is the most common service component, with degradation typically manifesting as erratic positioning or feedback alarms. Bearing wear in high-cycle applications is another frequent issue. Both are repairable by qualified FANUC service providers and generally represent more economical solutions than complete motor replacement.
The FANUC A06B-0205-B200 is an OEM replacement component. Always verify shaft configuration, encoder type, and amplifier compatibility with your machine documentation prior to installation.
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