FANUC A06B-0221-B100 | AC4/3000i AC Servo Motor — 4 Nm / 3000 rpm / Straight Smooth Shaft / a1000 Encoder

AC4/3000i — 4 Nm at 3000 rpm for Feed and Auxiliary Axes

The A06B-0221-B100 is FANUC's AC4/3000i servo motor from the Alpha C series — 4 Nm continuous torque at 3000 rpm maximum speed. This torque-speed combination targets primary feed axes on compact CNC machining centres, lathes, and multi-function machines where steady torque at moderate speed is the design requirement. Four Newton-metres is enough to drive a medium-pitch ballscrew directly on a compact axis without a gearbox.

The smooth shaft (SLK) transmits torque entirely through friction clamping at the coupling hub. No keyway means no geometric discontinuity in the shaft — coupling hubs clamp directly onto the polished shaft surface. Inspect the hub clamping torque at installation and periodically in service. On a 4 Nm motor under sustained reversing loads, a clamping hub that has relaxed can develop micro-slip that accumulates into positioning error over time.

The B100 configuration carries no electromagnetic brake. Position at servo-off is maintained by active servo lock. For gravity-loaded or vertical axes where mechanical holding at servo-off is required, specify the brake variant within the A06B-0221 series.

Key Specifications

a1000 Encoder — Incremental, Homing Required at Power-Up

The a1000 is an incremental encoder. The CNC must complete a reference-return cycle at each power-up to establish the axis position datum. This is standard operating behaviour for machines fitted with Alpha C incremental encoder motors. For absolute position on power-up without homing, the variant with an absolute encoder is required.

The encoder is sensitive to mechanical shock — avoid impacting the motor shaft during installation and removal. Do not perform insulation resistance (megger) tests on the motor windings with the encoder cable connected. The encoder electronics are not rated for the high-voltage test pulse.

FAQ

Q1: What amplifiers are compatible with the A06B-0221-B100?

FANUC Alpha C series servo amplifiers matched to the AC4/3000i motor class. Confirm the amplifier's rated current covers the motor's rated current. The a1000 incremental encoder requires the corresponding encoder interface in the amplifier — verify encoder interface type compatibility before pairing.

Q2: The machine requires homing at every power-up. Is this related to the a1000 encoder?

Yes. The a1000 is incremental — no absolute position memory. Reference return at power-up is required and normal. For absolute position without homing, a motor with an absolute encoder from the same A06B-0221 series is needed.

Q3: Is the smooth shaft (SLK) suitable for belt drives?

Yes, with correct coupling selection. The coupling hub must be a smooth-bore friction type sized for the shaft diameter. For belt-drive applications, the hub clamping specification must account for belt tension in addition to transmitted torque. Insufficient clamping force under belt tension and torque reversal can cause hub creep.

Q4: After replacing the motor, the axis following error is larger than expected.

Check the CNC motor type parameter — a mismatch causes persistent following error. Verify the encoder cable is fully seated at the amplifier feedback connector. Check the smooth-shaft hub clamping: an insufficiently clamped hub produces mechanical misalignment that adds friction and increases the following error before the coupling eventually slips.

Q5: Where is the A06B-0221-B100 sourced?

Through the FANUC Alpha C motor aftermarket — specialist CNC motor dealers and repair/exchange services. Confirm the B100 suffix (smooth shaft, a1000, no brake) from the installed motor's nameplate before ordering.