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Machine brand
Fanuc Spindle Repair and Rebuild
We repair and rebuild Fanuc spindle motors and the spindle units they sit in: built-in motor spindles, belt-driven AC spindle motors and BT or HSK toolholder cartridges. We are an independent workshop in Sankt Augustin, Germany, working on all machine brands. Send the unit to us directly, or ask about on-site work, which is possible by prior technical arrangement.
Scope
Fanuc spindle systems we work on
Fanuc is not primarily a machine tool builder. It makes controls, drives and spindle motors, and those motors are fitted inside machines from dozens of other builders. So a Fanuc spindle usually reaches us as a motor or a cartridge out of someone else's machine. The mechanical work is ours to do. Anything that turns out to be a drive or parameter fault has to be identified as such, not replaced blindly.
Built-in motor spindles
The rotor is shrunk onto the spindle shaft, so a winding fault, a bearing fault and a thermal problem all look alike from outside. These units are stripped completely, the winding and insulation are measured, and the bearings are refitted with the preload determined for that spindle type.
Belt and gear driven spindle motors
Alpha and alpha i series AC spindle motors that drive a separate spindle head through a belt or gear train. Side load from belt tension wears the drive-end bearing first. We renew bearings, check shaft and pulley seats, and refit the built-in speed sensor so orientation still works afterwards.
BT and HSK toolholder spindles
Machining centre cartridges with a BT, CAT or HSK interface driven by a Fanuc motor. The taper takes the damage: fretting at the flank, a picked-up face on HSK, a worn clamping set. Tapers are reground to the relevant ISO or DIN form and runout is measured against the bearing journals.
Robodrill and compact BT30 spindles
Units reaching us usually come from Robodrill alpha-D series machines and similar compact BT30 heads. They run fast, the bearings are small, and grease life rather than load often decides when they fail. Rebuild covers bearing renewal, seal and air-purge condition, and balancing of the rotating assembly.
The exact configuration depends on the machine model and the year of manufacture. Two machines with the same model designation can carry different spindle units, so we confirm the build from your nameplate photograph before quoting.
Symptoms
Faults we see most often on Fanuc spindles
Noise and rising vibration
On built-in motor spindles the first sign is usually a change in noise at one speed band. We strip, measure the bearing seats and balance the rotating assembly to ISO 21940 grades.
Overheating and thermal drift
A Fanuc motor spindle that runs hot may have a failing bearing, a blocked cooling jacket or a clogged motor fan. We separate the three during teardown rather than guessing from the alarm code.
Runout at the taper
Usually a crash or tool changes under load. The taper is reground and runout corrected against the bearing journals; if the shaft itself is bent, we say so before spending money on the rest.
Tool clamping problems
Drawbar springs lose force gradually, so tools pull out under heavy cuts long before anything sounds wrong. Clamping force is measured, the spring stack and gripper renewed, and the release stroke reset.
Encoder and orientation faults
Fanuc spindles use a built-in speed sensor or a separate position coder for orientation. Contamination, a loose sensor ring or a damaged cable give similar alarms; we check the mechanical side and report what we find.
Coolant or grease ingress
Coolant past a labyrinth seal reaches the bearings and, on built-in units, the winding. Insulation resistance is measured before anything else, since a wet winding decides whether a rewind is needed.
Process
What a repair looks like
The spindle is logged in and inspected on arrival, then dismantled completely. We measure shaft and housing geometry, check the bearing seats, inspect windings and encoder, and photograph what we find. You receive a written quotation with the scope of work before anything is repaired. After the work is done the unit is dynamically balanced, run-in tested and shipped with a test report containing the measured values.
The individual operations — bearing replacement, rotor and stator rewinding, taper regrinding, drawbar and clamping repair, encoder work, seal and cooling circuit overhaul — are described on the services section of our homepage. On a Fanuc spindle they are usually combined into one rebuild rather than ordered separately.
What to send with your enquiry
- Photographs of the spindle nameplate and of the tool interface
- Machine model, spindle type and year of manufacture
- A short description of the symptoms and when they appear
- Any measurements you already have — runout, temperature, vibration, current draw
- Whether the machine is still assembled or the spindle is already removed
Removal should be carried out by qualified personnel following the machine documentation. If that is not possible on site, ask us about removal and refitting as part of an on-site visit.
Shipping and on-site service
Our workshop is in Germany and we have no branch, warehouse or permanent staff in other countries. Customers outside Germany send the spindle to us by freight forwarder; we inspect, repair, test and return it. On-site work — removal, installation, alignment and commissioning — is possible internationally, but only after the job has been agreed technically in advance, so that the right parts and instruments travel with the technician.
Questions
Fanuc spindle repair — frequently asked
Yes. We are an independent workshop, so you can send a spindle or a spindle motor to us directly. There is no dealer in the middle, and we are not tied to one manufacturer's parts catalogue. What we cannot do is claim any form of Fanuc authorisation. We have none, and we say so plainly.
Units reaching us usually come out of machines built by other manufacturers that chose Fanuc drives and motors, along with Fanuc's own Robodrill machining centres. The plate on the motor therefore tells us less than the machine it was fitted in. Send the machine type together with the motor plate data and we can work from both.
Often, yes, but not from a photograph of an alarm screen. Winding resistance, insulation resistance and sensor output are measured on the bench, and the mechanical condition is judged during teardown. If everything measures normal, the fault probably sits in the drive, the cable or the parameters, and we tell you that instead of selling a rebuild.
Typically five to ten working days from arrival, depending on parts availability and what the teardown reveals. That is an estimate, not a committed date, and a binding date is only valid if we confirm it in writing. Rewinding, a taper regrind or a bearing size that has to be ordered specially pushes the longer end of that range.
The unit is stripped and measured, and you receive a written quotation before any repair work starts. The assessment is charged according to the size and type of spindle, so tell us what you have and we will say what it will cost. If you decide against the repair, the spindle is returned or scrapped as you prefer.
Send us the spindle details
Tell us the machine model, the spindle type and what the machine is doing wrong. We come back with an initial assessment and a written quote before any work begins.