A06B-0123-B077 Fanuc AC Servo Motor A06B0123B077 AO6B-OI23-BO77

FANUC A06B-0123-B077 | Alpha 3/3000 AC Servo Motor — Taper Shaft / i64 Incremental Encoder / No Brake

Part Number: A06B-0123-B077

Cross Reference: A06B0123B077

Manufacturer: FANUC Corporation (Japan)

Product Type: AC Brushless Servo Motor — Alpha Series (Red Cap) 

Alpha 3/3000 — A Workhorse Motor for Machine Tool Feed Axes

The A06B-0123-B077 is the Alpha 3/3000 servo motor — 3 Nm, 3000 rpm, with FANUC's i64 incremental pulsecoder. This is the Alpha red-cap generation: the series that defined FANUC servo motor performance through the late 1990s and 2000s. At 3 Nm, it covers the mid-range of machine tool feed axis requirements — X, Y, and Z axes on small vertical machining centres, turret indexing drives, and tailstock feeds on turning centres.

The B077 suffix in FANUC's Alpha motor ordering system identifies this specific configuration: tapered shaft with keyway and i64 incremental encoder, no brake. This is the standard configuration for horizontal or vertically-balanced axes where a brake is not required and the axis can be held at servo-on by the amplifier's closed position loop.

i64 Incremental Encoder — What It Means in Practice

The i64 encoder provides 64,000 feedback pulses per revolution after quadrature interpolation by the servo amplifier. It is an incremental encoder: at each power-up, position starts from an arbitrary reference and must be established by a machine reference-return cycle before production can start. This is standard and expected on machines built with Alpha series drives.

For machines requiring absolute position on power-up (no homing cycle), the A06B-0123-B075 variant — which carries an A64 absolute pulsecoder — is the alternative. Mechanically both variants are identical (same flange, shaft, torque specification). The encoder is the only difference

Key Specifications

FAQ

Q1: What servo amplifiers are compatible with the A06B-0123-B077?

The Alpha 3/3000 uses 40A-class SVM amplifier channels: SVM1-40S (A06B-6079-H103), SVM2-12/40 (A06B-6079-H204), SVM2-20/40 (A06B-6079-H205), and their A06B-6096 equivalents. The motor is typically assigned to the L or M axis position in multi-axis SVM configurations.

Q2: The machine requires homing after every power cycle. Is this because of the i64 encoder?

Yes. The i64 is an incremental encoder — it counts from zero at each power-up. A reference-return cycle (homing) is required after every power cycle to re-establish the machine's position reference. This is the expected and normal behaviour for machines built with Alpha series incremental encoder motors. It is not a fault.

Q3: Can A06B-0123-B077 (i64) substitute for A06B-0123-B075 (A64 absolute) in a machine that uses absolute position?

No. A machine configured to use absolute encoder feedback (no homing cycle) depends on the A64 encoder's ability to report position on power-up. Replacing with an i64-equipped motor means the CNC will alarm on power-up because it cannot read absolute position. The encoder type is set in the CNC's axis parameter — changing encoder type requires parameter changes that may affect servo performance tuning.

Q4: After reinstalling the A06B-0123-B077, the axis following error is larger than before. What should be investigated?

A larger-than-normal following error after motor reinstallation typically indicates the encoder cable is not fully seated at the amplifier's JV connector, the coupling between the motor and the ballscrew is misaligned or loose, or the servo gain parameters need re-verification. Check the mechanical connection first — slight misalignment at the coupling increases friction, which produces a consistent following error the position loop cannot fully correct at the gain settings.

Q5: Where is the A06B-0123-B077 sourced?

Alpha 3/3000 motors are widely available in the FANUC aftermarket — both new surplus and refurbished exchange units. Motor rebuild services covering encoder replacement, new bearings, seals, and shaft restoration are available for units with mechanical damage. Confirm the i64 pulsecoder alignment is verified as part of any rebuilt motor's acceptance test.