New Fanuc A06B-0205-B000 — αiF 2/5000 Compact AC Servo Motor, Taper Shaft, No Brake, Absolute A1000 Pulse Coder

Product Overview

Part Number: A06B-0205-B000

Condition: New

Also Searched As: A06B0205B000, Fanuc A06B-0205-B000, FANUC A06B0205B000

Motor Model: αiF 2/5000

Classification: Fanuc Alpha iF Series AC Brushless Servo Motor — 2 Nm Stall Torque, 5,000 rpm Max Speed, Taper Shaft with Key, No Brake, Absolute A1000 Pulse Coder, IP65

New Stock — Why It Matters for This Motor

The A06B-0205-B000 listed here is new — not refurbished, not exchange-rebuilt, not tested surplus. For a motor that lives on a precision CNC axis and carries the machine's position feedback in its pulse coder, the difference between new and refurbished is not merely cosmetic.

A new A06B-0205-B000 ships with factory-fresh bearings at zero accumulated hours, an encoder aligned and calibrated at the Fanuc factory, seals that have never been exposed to coolant or contamination, and a taper shaft geometry ground to Fanuc's dimensional specification without any service wear. For machines running production schedules where reliability is a business constraint and unplanned downtime has a real cost, starting with a new motor is the right investment.

Technical Specifications

The αiF 2/5000 — Small Frame, High Speed, Real Capability

Some machine axes do not need eight Newton-metres of stall torque. They need a motor that is physically compact, responsive, and fast — one that fits into the mechanical envelope the machine designer allocated, delivers what the load actually demands, and moves quickly enough that it does not become the cycle time bottleneck.

That is the application the αiF 2/5000 was designed for.

Two Newton-metres of stall torque covers the sustained load demands of lightweight CNC axes: small spindle head assemblies, subsidiary Z-feeds on turning centres, compact tool magazine drives, and auxiliary positioning axes where the load mass is low and the primary requirement is accurate, repeatable positioning at speed. The 8.3 Nm maximum torque available during acceleration transients gives the axis real dynamic performance — the ability to reach speed quickly on short-stroke moves — even though the sustained torque rating is modest.

Five thousand rpm maximum speed is the other half of the equation. For a 5mm pitch ball screw in direct coupling, 4,000 rpm rated speed produces 20 m/min of linear traverse. That is fast enough for productive rapid traverse on compact machines without any intermediate reduction. The high maximum speed is what allows this small motor to cover axes that physically cannot accommodate a larger motor but still need meaningful traversal performance.

0.75 kW at 96% power factor. The motor draws less reactive current than most machines' panel designers need to account for, which helps in panel energy budgeting and reduces heat generated in the drive supply chain.

No Brake: The Right Configuration for Most Horizontal Axes

The B000 suffix confirms no electromagnetic brake. This is not an omission — it is the correct specification for the majority of applications where the A06B-0205-B000 is used.

Position at rest is maintained by the Fanuc αi servo amplifier's servo lock. With the position loop active and the A1000 reporting 1,000,000 counts per revolution, the amplifier continuously supplies corrective current to hold the commanded shaft angle. On horizontal axes and axes where no net gravitational force acts in the direction of shaft rotation, this hold is reliable and accurate. The shaft does not drift, and the CNC position register remains exactly at the commanded coordinate.

The practical advantage of the no-brake configuration compounds across every axis fitted this way. No 24V DC brake circuit to wire in the panel. No brake relay, no surge suppression component, no brake coil timing in the CNC startup sequence. No brake disc wear to monitor over the motor's service life. Lighter and shorter motor body than the equivalent braked variants. For a machine with multiple small servo axes, these simplifications are meaningful across both initial installation and lifetime maintenance.

Where an axis is vertical or carries a gravitational load component along the direction of shaft rotation, servo lock is not adequate at servo-off. Those applications need a braked motor — the A06B-0205-B300 (24V brake, taper shaft) or A06B-0205-B400 (24V brake, straight smooth shaft) within the same αiF 2/5000 family. The A06B-0205-B000 is correctly and confidently specified for horizontal and symmetrically loaded axes.

Taper Shaft with Key: Precision From the First Installation

Every A06B-0205-B000 shipped new from Fanuc arrives with a precision-ground taper shaft and key. This is the machine tool standard coupling interface, and it earns that status through properties that matter across the motor's full service life.

The taper is a precisely machined cone angle on the motor shaft end. When the coupling hub is pulled onto the shaft using a draw bolt threaded into the shaft-end hole, the taper geometry automatically centres the hub — the motor shaft and driven shaft axes align to tight dimensional tolerance without any manual adjustment. The key in the matched keyway slots transmits torque mechanically through the key's shear cross-section, not through friction clamping. The 2 Nm stall torque and 8.3 Nm peak torque are transmitted through this positive mechanical connection, which does not loosen under vibration, does not require retightening, and does not degrade with thermal cycling.

On a new motor, the taper geometry is guaranteed to Fanuc's dimensional specification. This is one of the real differences between a new motor and a refurbished one — a taper shaft that has been removed and reinstalled multiple times, or that was repaired with shaft work after physical damage, may not hold the same geometry. A new A06B-0205-B000 starts the installation with the coupling geometry exactly where Fanuc intended it to be.

Alpha i A1000 Pulse Coder: The Absolute Advantage in Daily Production

Every A06B-0205-B000 carries the Alpha i A1000 serial absolute pulse coder — 1,000,000 pulses per revolution, retained through power-off events by the backup battery in the Fanuc αi servo amplifier.

On a new motor, the A1000 encoder is factory-aligned and calibrated. On a refurbished motor, encoder alignment depends on the quality of the rebuild facility's alignment process and equipment — a variable that matters on a precision axis. Starting with a new A06B-0205-B000 means the encoder alignment is the Fanuc factory standard, not an approximation of it.

The operational consequence of the absolute encoder is the same regardless of motor condition: when the CNC powers up — after a planned shutdown, after a power interruption, after an alarm — the axis coordinate is established immediately without any homing movement. For machines that cycle power between shifts, this means faster restarts. For machines that stop mid-cycle on an alarm, this means the axis resumes from exactly the stopped position without the supervised homing routine that incremental encoders require.

At 1,000,000 counts per revolution, the position loop resolution is 5 nanometres per count on a 5mm pitch ball screw. The CNC closes the position loop at this resolution, which is what delivers the sub-micron repeatability precision machines are built around.

The backup battery in the amplifier, not in the motor, maintains the multi-turn counter through power-off. Replace it when the Fanuc CNC issues a battery alarm — a depleted battery resets the counter and forces a homing cycle.

A06B-0205 Family: Understanding the Options

The A06B-0205 series covers the full αiF 2/5000 configuration range:

The B000 is the clean baseline: taper shaft, no brake, absolute encoder. The correct choice for horizontal axes on machines with 24V brake supply in place for other axes — the B000 simplifies the panel on every axis that does not need the brake.

Compatible Amplifiers and CNC Systems

The A06B-0205-B000 operates with Fanuc αi series servo amplifiers (αiSV) — specifically the αiSV 4 for this motor's 0.75 kW / 2 Nm power level. Compatible CNC platforms include Fanuc Series 0i-D, 0i-F, 15i, 16i, 18i, 21i, 30i-A, 30i-B, 31i-A, 31i-B, and 32i. Not compatible with first-generation α or αC series amplifiers, or with Fanuc β series drives.

When fitting the A06B-0205-B000 as a replacement, verify the CNC axis parameters match the αiF 2/5000 motor type entry in Fanuc's servo parameter database. Parameter mismatches produce unstable servo performance or amplifier faults on startup. On new motor installations, the motor type detection available on more recent CNC versions may populate parameters automatically from the A1000 pulse coder data — verify the result against the expected configuration before proceeding to production.

Typical Applications

Auxiliary and subsidiary CNC machine tool feed axes. Secondary Z-feeds, Y-axis drives on compact turning centres, and subsidiary positioning axes on multi-task machines where the load is light and the axis fits within the 0.75 kW / 2 Nm budget.

Compact drill-tap and machining centre feed axes. X, Y, and Z drives on small drill-tap centres, desktop machining centres, and compact 5-axis machines where space constraints and load requirements align with the αiF 2/5000's capabilities.

Rotary tool magazine and ATC mechanism drives. Tool magazine indexing drives, ATC arm traverse axes, and tool chain drives on CNC machining centres where the mechanism mass and load fit the 2 Nm torque range.

Multi-axis turning centre C-axis and live tool positioning. C-axis positioning drives and live tool orientation axes on CNC turning centres where the αiF 2/5000's high speed and absolute encoder suit the axis kinematic requirements.

Fanuc robot and positioner subsidiary drives. Secondary axis drives on Fanuc robots and programmable positioners where the αiF 2/5000 size, speed, and αi compatibility match the joint's mechanical and control requirements.

FAQ

Q1: Why choose a new A06B-0205-B000 over a refurbished unit?

A new motor guarantees factory-original bearing hours (zero), factory-aligned and calibrated A1000 encoder, factory-spec taper shaft geometry, and original sealing integrity. Refurbished motors vary in quality depending on the rebuild facility's process — bearing replacement practice, encoder alignment method, and shaft inspection standards differ across suppliers. For a precision CNC axis where encoder alignment directly affects positioning accuracy and bearing condition determines when the next failure occurs, a new factory unit removes those variables entirely. Where budget is the primary constraint and the rebuild source is known and trusted, a quality refurbished unit may be acceptable; for critical production axes, new is the lower-risk choice.

Q2: Does the A06B-0205-B000 require a homing cycle every time the CNC powers up?

No. The Alpha i A1000 is a serial absolute encoder — it retains multi-turn shaft position through power-off events via a backup battery in the Fanuc αi servo amplifier. When the CNC powers up, the axis coordinate is established immediately without any axis movement. There is no reference-return cycle required. This is a significant operational advantage over incremental encoder motors (such as the B001 variant), which require homing on every power-up and after every alarm recovery.

Q3: Which Fanuc amplifier and CNC systems are compatible?

The A06B-0205-B000 requires a Fanuc αi series servo amplifier (αiSV 4) at this power level. Compatible CNC platforms include Fanuc Series 0i-D, 0i-F, 15i, 16i, 18i, 21i, 30i, and 31i. It is not compatible with first-generation α or αC amplifiers, or with β series drives. Always verify CNC axis parameters are set to the αiF 2/5000 motor type from Fanuc's parameter database before commissioning.

Q4: Can this motor be used on a vertical axis without a brake?

On a vertical axis or any axis where gravity acts along the direction of shaft rotation, the motor must have a brake — the B000 has none. Servo lock holds position only while the amplifier is powered and active. Any event that removes servo power — E-stop, amplifier fault, mains interruption, or planned shutdown — leaves a brakeless vertical axis free to move under gravity. For vertical axes, specify the A06B-0205-B300 (taper shaft, 24V spring-applied brake, A1000 absolute encoder) within the same αiF 2/5000 family. The B000 is correctly specified for confirmed horizontal axes with no gravitational load component.

Q5: What is the maximum speed rating and when is it usable?

The rated speed is 4,000 rpm — the speed at which 0.75 kW continuous rated output is guaranteed. The maximum speed is 5,000 rpm, available in the constant-power field-weakening region above rated speed, where available torque decreases as speed increases. Operation above 4,000 rpm is possible on light-load axes where the torque demand at higher speed stays within the motor's reduced capability at that operating point. For axis duty cycles that include sustained operation above 4,000 rpm, verify the torque-speed curve against the load requirement before relying on above-rated-speed operation for production machining phases.