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| Place of Origin | JAPAN |
| Brand Name | Fanuc |
| Certification | CE ROHS |
| Model Number | A06B-0162-B575#0008 |
The FANUC A06B-0162-B575#0008 is a three-phase AC servo motor from FANUC's Alpha (α) series, designated model αM6/3000 — 6 Nm rated torque at a maximum speed of 3,000 rpm, delivering 1.4 kW of continuous rated output. This specific configuration combines a straight shaft with keyway (#0008), no brake, and an αA64 absolute pulsecoder — making it the preferred choice for feed-axis applications where reliable absolute position retention is required and a holding brake is not specified by the machine builder.
The A06B-0162-B575#0008 belongs to the αM sub-series within FANUC's Alpha motor family, a group of compact, sealed servo motors engineered specifically for small to medium CNC machine tool feed drives, including vertical machining centres, CNC lathes, and multi-axis grinding machines.
| Parameter | Value |
|---|---|
| FANUC Part Number | A06B-0162-B575#0008 |
| Motor Series | FANUC Alpha (α) — αM Sub-series |
| Motor Model Designation | αM6/3000 |
| Rated Output | 1.4 kW |
| Rated Torque | 6 Nm |
| Rated Speed | 3,000 rpm |
| Rated Current | 6 A |
| Supply Voltage (from amplifier) | 144 V AC, 3-phase |
| Frequency | 200 Hz |
| Feedback Encoder | αA64 Absolute Pulsecoder (64,000 ppr) |
| Shaft Type | Straight |
| Shaft Keyway | Yes (#0008) |
| Holding Brake | None |
| Sealing Standard | IP67 |
FANUC's Alpha servo motor family covers an extensive range of torque and speed ratings, but within it the αM sub-series occupies a particular niche: motors designed for compact installation on medium-duty machine tool axes, where lower inertia and fast dynamic response matter more than peak output. The αM6/3000 sits at the lower end of the αM torque range — above the αM2/3000 and αM2.5/3000 — and is widely encountered on X, Y, and Z axes of smaller vertical machining centres, CNC turret lathes, and precision grinding machines that were built during FANUC's Alpha generation production period.
What the "M" designation conveys is straightforward: these are medium-inertia motors with a frame design optimised for the dimensional envelope of machine tool axis saddles and headstocks. They share the same sealed construction and αA64 pulsecoder as the larger Alpha family motors, but their smaller flange size and lower mass make them easier to integrate into tightly packaged machine designs where the motor must mount directly behind a ballscrew support bearing.
The B575 base part number specifies a straight shaft without a brake. The #0008 modification code adds a keyway to the shaft — a tangential key slot machined into the motor output shaft that accepts a standard parallel key.
The practical difference between a plain straight shaft and a keyed shaft comes down to how the motor couples to the machine drivetrain. A smooth shaft relies on interference fit or clamping alone; the keyway adds a positive mechanical locking feature that prevents shaft rotation under high radial or torsional loads. In machine tools where the motor drives a ballscrew through a coupling with keyway bores, or where the design requires a driven pulley retained by a key, the #0008 shaft is the correct specification. Substituting a plain shaft in these applications risks coupling slip under peak torque loads — a service issue that typically presents as axis positioning error under heavy cutting conditions.
The αA64 pulsecoder is an optical absolute encoder with a resolution of 64,000 pulses per revolution. Unlike incremental encoders, which lose position information when power is removed, the αA64 retains the absolute shaft position across power cycles using a lithium battery located inside the servo amplifier — not inside the motor itself. The encoder communicates position data to the amplifier over a serial interface; at power-up, the CNC reads the stored absolute position and is ready for machining without a reference return run.
This architecture has a practical consequence for maintenance: the encoder battery is in the amplifier, not the motor. When replacing the motor or the encoder, the battery backup circuit in the amplifier manages position retention independently. If the battery is discharged at the time of motor replacement, a reference return may be required on the affected axis before the machine can resume fully automatic operation.
The αA64 pulsecoder is sealed within the motor rear housing and is not a user-serviceable component. Encoder failure — typically characterised by SV0447 or SV0448 alarms on FANUC CNCs — requires encoder unit replacement or full motor repair/exchange.
The A06B-0162-B575#0008 requires a FANUC servo amplifier rated at 80 A peak for the M-axis channel. Compatible amplifier modules confirmed for this motor include:
α Series Amplifiers (A06B-6079-xxxx):
αi Series Amplifiers (A06B-6096-xxxx):
SVU Series Amplifiers (A06B-6089-xxxx):
Amplifier selection must match the machine's original electrical design. When sourcing a replacement motor for an existing machine, the amplifier currently installed determines which motor model is acceptable — do not change the motor's rated current or torque class without verifying amplifier compatibility.
Minimised Torque Ripple FANUC designed the Alpha motor's magnetic pole geometry specifically to suppress torque ripple. Smooth, ripple-free torque is directly visible in surface finish quality during finishing cuts, particularly on contouring paths where axis velocity is constant but cutting direction changes continuously. The combination of the optimised pole shape, the αA64 pulsecoder's high resolution, and FANUC's HRV (High Response Vector) current control produces a motor that rotates smoothly even at very low speeds — an important characteristic for axes used in thread-cutting and die-sinking operations.
Sealed Construction to IP67 The αM series motors carry an IP67 rating — fully dust-tight, and capable of withstanding temporary immersion in water. In the environment of a CNC machine tool, where coolant, oil mist, and swarf are present continuously, IP67 sealing provides meaningful protection over the long service periods these machines are expected to run. FANUC's sealed Alpha motors use a stator seal and waterproof connectors to prevent coolant ingress; however, FANUC notes in its product documentation that IP67 is verified for short-duration immersion and does not guarantee protection against continuously directed coolant spray. Machines where coolant is applied directly to the motor body should be reviewed against the motor's specific installation guidance.
Compact High-Torque Rotor Design The αM series uses a rotor geometry that delivers comparatively high torque for the motor's physical envelope. Smaller, lighter motors with adequate torque density reduce the moving mass of the machine axes, which in turn reduces the acceleration and deceleration energy required and allows tighter servo loop gains — contributing to shorter cycle times and better contouring accuracy.
| Part Number | Shaft | Brake | Encoder | Keyway |
|---|---|---|---|---|
| A06B-0162-B575 | Straight | None | αA64 Absolute | No |
| A06B-0162-B575#0008 | Straight | None | αA64 Absolute | Yes |
| A06B-0162-B775 | Straight | HP Brake | αA64 Absolute | No |
| A06B-0162-B775#0008 | Straight | HP Brake | αA64 Absolute | Yes |
| A06B-0162-B175 | Taper | Standard Brake | αA64 Absolute | — |
| A06B-0162-B177 | Straight | Standard Brake | αA64 Absolute | No |
All variants are the same αM6/3000 motor core: 1.4 kW, 6 Nm, 3,000 rpm, 144 V, 200 Hz, 6 A.
The αM6/3000 motor has been fitted across a wide range of FANUC-controlled machine tools from Japanese, European, and Taiwanese machine builders. Common applications include:
The "red cap" appearance of the encoder end of the motor — characteristic of the Alpha generation — makes the motor visually recognisable on the machine, and it is frequently encountered on machines built from the mid-1990s through the mid-2000s that are still actively running in production.
Q1: What is the difference between the A06B-0162-B575#0008 and A06B-0162-B575, and do both fit the same mounting location?
The only difference between the two part numbers is the shaft keyway. The B575 (without a suffix modifier, or with #0000) is a plain straight shaft with no key slot; the #0008 variant has a keyway machined into the output shaft. Both motors are mechanically and electrically identical in every other respect — same flange dimensions, same rated specifications, same encoder. Whether the keyway is required depends entirely on the coupling or pulley being used at the machine end. A coupling with a bored keyway must use the #0008 shaft; a smooth-bore clamping coupling or a coupling that grips by friction alone can use either. Installing a motor with a keyway into a smooth-bore coupling is physically possible but mechanically redundant — the opposite (smooth shaft into a keyed coupling bore) will not transmit torque reliably under load.
Q2: The αA64 encoder is listed as absolute. Does this mean the machine never needs a reference return after power-up?
Normally, yes — the absolute pulsecoder retains shaft position data even when the machine is powered off, so the CNC reads the stored absolute position at every startup and the axis is ready without a reference run. This relies on the encoder battery inside the servo amplifier remaining charged. If the battery voltage drops below the threshold, stored position data is lost and a reference return (or manual zero-return) is required on all battery-backed axes. FANUC recommends replacing the amplifier battery on a scheduled basis — typically every two to three years in machines in regular production — before a low-battery alarm appears. The alarm is FANUC alarm SV5136 (Battery Voltage Low) or SV5137 (Battery Voltage Zero) depending on the CNC model; the former is a warning that allows planned battery replacement, the latter means data has already been lost.
Q3: Can this motor be run on an αi series amplifier, even though it is an Alpha (non-i) generation motor?
Yes. The αA64 absolute pulsecoder used in the A06B-0162-B575#0008 is compatible with both the α series amplifiers (A06B-6079-xxxx and A06B-6089-xxxx) and the αi series amplifiers (A06B-6096-xxxx). FANUC designed the αi series amplifiers to accept the encoder signals and motor power specifications of the preceding Alpha motor series, allowing machines to be retrofitted with newer amplifiers without necessarily replacing motors. The critical requirement is that the amplifier's rated motor current matches the motor's 6 A continuous rating. When installing the motor on an αi amplifier that previously drove a different motor, the motor ID parameters in the CNC must be updated to match the αM6/3000 specification; the parameter table is found in the FANUC Servo Motor/Amplifier Parameter Manual (B-65270EN).
Q4: What are the most common failure modes found on the A06B-0162-B575#0008 in service?
Based on documented repair records from servo motor repair specialists, the most frequently reported failure conditions on this motor are: bearing failure at the drive-end (DE) bearing and/or the opposite drive-end (ODE) bearing — typically presenting as vibration, noise, or axis alarm SV0436 (excess velocity deviation) under cutting load; encoder (pulsecoder) malfunction due to optical element degradation or connector corrosion, presenting as SV0447/SV0448 alarms; coil insulation failure following coolant ingress through damaged shaft seals or connector seals; and power connector damage. Bearing replacement is a standard repair; encoder unit replacement is more complex and should be performed by a servo motor repair facility with appropriate test equipment. Before condemning the motor for encoder alarms, verify that the encoder cable and connector at the amplifier end are intact and that the battery voltage is adequate.
Q5: Is this motor still available new, or is it obsolete? What are the options if a new unit cannot be sourced?
The FANUC Alpha (α) series — as distinct from the current αi and αiS series — has been discontinued as a production item by FANUC. New units of the A06B-0162-B575#0008 are no longer manufactured. The available sourcing options are: new-old-stock (NOS) units from industrial parts distributors who purchased inventory before discontinuation; fully refurbished/exchange units from servo motor repair specialists who rebuild motors to original specification with new bearings, seals, and encoder components; or a cross-series substitution to a compatible αi series motor such as the A06B-0227-B*** (αiF 8/3000 series), which requires verification of amplifier compatibility and may require machine parameter updates. Any substitution of a different motor model requires a qualified FANUC engineer or approved service provider to re-parameterise the axis — the motor ID, current limits, and servo gain parameters must all be updated to match the replacement motor's specification.
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