Family Electronic Fanuc AC Industrial Servo Motor Drives A06B-0116-B503

FANUC A06B-0116-B503 | Beta iS 1/6000 AC Servo Motor — Straight Shaft / Keyway / 24V Spring Brake / b64iA Encoder

Part Number: A06B-0116-B503

Manufacturer: FANUC Corporation (Japan)

Product Type: AC Brushless Servo Motor — Beta iS Series

Motor Model: BiS 1/6000 (Beta iS 1 / 6000 rpm) 

Beta iS — Compact High-Speed with Spring Brake

The A06B-0116-B503 is FANUC's Beta iS 1/6000 servo motor — the 1 Nm class, 6,000 rpm, compact-frame motor from the Beta iS (improved Standard) generation. At 0.5 kW and 1.2 Nm rated, it targets light-duty servo axes on smaller CNC machine tools, handling X, Y, or Z positions where the combination of high speed and compact size is the design priority.

The spring-applied 24V electromagnetic brake is the key configuration detail on this variant. The brake is on by default — the spring holds the brake pads against the disc whenever the 24V coil is not energised. The coil must be energised (24V DC applied) to release the brake for normal servo operation. At servo-off, E-stop, or power loss, the coil de-energises and the brake locks the shaft immediately. This design is standard for vertical axes, inclined feeds, and any mechanism where the load applies a gravity force in the direction of shaft rotation when the servo is not actively commanding motion.

The b64iA encoder is an incremental type — 64 signal periods per revolution, processed to higher resolution by the servo amplifier's electronics. Position reference is established by a homing cycle at power-up.

The straight shaft with machined keyway provides a positive torque drive. At 6,000 rpm and frequent reversals, a keyed connection is more reliable than a friction-clamp hub over extended production service life.

Key Specifications

FAQ

Q1: The axis shows a brake alarm at power-on. The 24V supply to the brake connector is confirmed present. Is the brake faulty?

With 24V confirmed at the connector, measure the resistance across the brake coil terminals (24V disconnected). A healthy brake coil on a motor of this class typically reads in the 15–40Ω range. Open circuit confirms a failed coil. If resistance is within range but the brake still does not release, check for mechanical binding in the brake disc — contamination or a seized spring can prevent release even with the coil energised.

Q2: The b64iA is an incremental encoder — does this motor require a homing cycle at every power-up?

Yes. The b64iA incremental encoder requires a reference-return (homing) cycle after each power cycle to establish the axis's position reference. The machine cannot produce parts at the correct position until homing is complete. If absolute position on power-up without homing is required, a Beta iS motor variant with an absolute encoder is the correct specification.

Q3: The B503 suffix indicates brake and keyway. What variant would be specified without a brake?

The B103 suffix identifies the straight shaft / keyway / no brake variant of the same BiS 1/6000 motor (same encoder, same electrical specification). The B503 and B103 are mechanically the same in flange, shaft, and body — the B503 adds the brake and its wiring connector. Use B103 for horizontal axes where servo lock holds position; use B503 for vertical or gravity-loaded axes.

Q4: After replacing the motor with A06B-0116-B503, the axis shows position drift at low speed. What should be investigated?

Position drift at low speed after a motor replacement often indicates the servo loop gain parameters do not match the new motor's characteristics, or the encoder cable is not properly shielded. Check the motor type parameter in the servo amplifier matches BiS 1/6000, and verify the encoder cable's shield is grounded correctly at the amplifier end. Also confirm the brake is fully releasing (24V present, coil resistance normal) — a partially applied brake creates a torque load that appears as apparent position drift.

Q5: Where is the A06B-0116-B503 sourced?

FANUC Beta iS series motors are available through the CNC aftermarket — new surplus, tested refurbished, and motor rebuild services. Confirm the full part number including B503 (not B103 or B503#suffix variants) on the nameplate. Brake function and encoder operation should both be verified in acceptance testing.