Case Study: Omlat 06478200 Spindle Rebuild After Compressor Oil Contamination
Case Study · Omlat 06478200
The Bearings Failed. The Air System Was the Problem.
This Omlat 06478200 arrived for inspection after performance concerns developed in production. Disassembly found compressor oil throughout the spindle — washed out of the front bearing grease, into the rear bearings, and inside the stator laminations.
New bearings alone would have solved nothing. Oil was still arriving through the pneumatic lines, and the spindle was heading for a major bearing failure. It was sent in early enough that the shaft and housing were still recoverable.
On This Page
Job Record
The Spindle and the Job
| Spindle make | Omlat |
| Model | 06478200 |
| Serial number | 080997 |
| Received for inspection | 27 October 2025 |
| Rebuild complete and reported | 14 November 2025 |
| Work performed | Full precision rebuild |
| Presenting complaint | Performance concerns developing in production |
| Root cause identified | Compressor oil ingression through the pneumatic supply |
Every spindle we take in is inspected first, then quoted. Nothing is scoped or priced before it comes apart, because the findings are what determine the work. On this unit the inspection turned up contamination well beyond a bearing job, and the quote reflected what was actually there rather than what the symptoms suggested.
Teardown
What Disassembly Revealed
Complete disassembly found compressor oil in three separate places inside the spindle. Each one tells the same story at a different stage of progression.
Front bearings — grease washed out
The front bearing set was damaged by compressor oil that had contaminated the grease and washed it out of the bearings. Once the grease is gone the lubricant film no longer carries the load, friction rises, and wear accelerates from there. This set was past the point of serviceability.
Rear bearings — overheating, nearing failure
Oil had migrated to the rear bearings and contaminated and washed the grease there as well, driving them to overheat. They were near failure condition when the spindle came in. This is the finding that determined the urgency of the job — the rear set was the one about to go.
Stator — oil inside the laminations
Compressor oil had reached inside the stator laminations. This is the finding that separates a contaminated spindle from a routine bearing job: oil in the motor is not something a bearing replacement addresses, and it does not clear itself. The stator had to be cleaned and all of the oil removed before the spindle could be reassembled.
The Pattern
Front bearings damaged, rear bearings overheating, oil in the stator. Three findings, one cause. Contamination that enters through the air supply does not stay where it lands — it travels, and it reaches components that have nothing to do with the symptom the operator originally noticed.
Root Cause
Compressor Oil Ingression
The oil came from the compressed air supply. Spindles rely on pneumatic air for pressurization, tool release, and sealing, and that air goes directly into the assembly. When a compressor passes oil downstream, the spindle receives it continuously, at pressure, in exactly the places designed to keep contamination out.
Oil arriving through the pneumatic lines can wash grease out of precision bearings, compromise seals, migrate into motor components, and affect tool release function. None of that announces itself. It shows up later as declining performance, which is exactly how this spindle presented.
Critical Warning
Correcting the oil ingression is not optional follow-up work — it is the repair. A rebuilt spindle returned to a plant still passing oil downstream is a rebuilt spindle on a countdown. This affects every spindle on that air system and every pneumatic component connected to it, not just the unit that failed first.
Work Performed
What the Rebuild Required
There is no standard rebuild — the scope is set by what disassembly finds. On this unit, the contamination was extensive enough that decontamination became a larger part of the job than the bearing work.
Complete disassembly and multi-stage cleaning
Every component was cleaned multiple times to eliminate oil residue. Single-pass cleaning does not remove oil that has worked into surfaces and joints over an extended period.
Stator decontamination
The stator required cleaning to remove all of the compressor oil that had reached the laminations. This is the step that added the most labor to the job, and it is not a step that can be skipped or shortened.
Component inspection and re-qualification
Each component was cleaned, inspected, and then either re-qualified for service or replaced. The structural elements came back within tolerance, which is what made a rebuild possible rather than a replacement.
Bearing replacement, front and rear
New sealed hybrid ceramic bearings were installed in both positions. Sealed bearings matter here specifically because of how this spindle failed: the seal is what stands between the grease and anything arriving through the air supply.
Drawbar service
New disc springs were installed on the drawbar, coated with the correct MetalFlux lubricant. Seals and O-rings were replaced throughout.
Dynamic balancing, before and after assembly
All rotating parts were dynamically balanced prior to final assembly and again after it. Balancing once and assuming assembly preserves it is how balance problems get built into a rebuilt spindle.
Clean room final assembly
Final cleaning, preparation, and assembly were completed in our Class 10,000 clean room. On a spindle that failed from contamination, reassembling it in open shop air would undo the decontamination work that preceded it.
Parts Record
Parts Installed
| Component | Designation | Detail |
|---|---|---|
| Bearing set | HYKH619112RZETAP4+DU | Sealed hybrid ceramic, 25-degree contact angle, P4 precision class |
| Bearing set | HYKH619092RZCTAP4+DU | Sealed hybrid ceramic, P4 precision class |
| Drawbar disc springs | STD-92012201 | 28 mm x 12.2 mm x 1.25 mm, 108 installed, coated with MetalFlux lubricant |
| Seals and O-rings | — | Replaced throughout as part of the rebuild |
Why sealed hybrid ceramic bearings on this rebuild
Hybrid ceramic bearings run steel races with ceramic rolling elements. The ceramic elements are lighter and generate less heat at speed, which improves thermal behavior and extends service life. The P4 designation is a precision tolerance class appropriate to spindle work.
The sealed construction is the part that matters most given how this spindle failed. This unit did not lose its bearings to normal wear — it lost them because contamination reached the grease and washed it out. A sealed bearing puts a physical barrier between the lubricant and whatever else is inside the housing.
Worth being clear about what sealed bearings do and do not do. They protect the grease inside the bearing. They do not stop oil entering the spindle, they do not protect the stator, and they do not fix the air system. They buy margin against a contamination source that should still be corrected at the source.
Verification
Testing and Certification Before Shipment
Once assembled, the spindle was run, broken in, tested, and certified. The following were verified and recorded before the unit was packaged:
- Run-in and thermal stabilization — the spindle was broken in under controlled conditions rather than being sent out cold
- Tool retention force — checked, verified, and recorded
- EM dimension — preset and recorded
- Proximity sensors — each one preset using an ISO/DIN standard certified master
Why Recorded Values Matter
Retention force, EM dimension, and sensor presets are documented so the plant has a known-good baseline. If this spindle drifts a year from now, those numbers are what make it possible to say whether something changed — rather than guessing against a memory of how it used to run.
Outcome
What the Timing Bought
The rear bearings were near failure when the spindle arrived. The plant sent it in on the strength of a performance change, not a breakdown — and that decision is the reason this was a rebuild rather than a replacement.
When a bearing set collapses in service, the damage stops being confined to the bearings. The shaft journals are exposed, housing geometry can be distorted, and once the housing bore is gone, the options narrow to replacement. None of that had happened here. The structural elements measured within tolerance, so the original housing and shaft went back into production.
| Condition at arrival | What continued running would likely have produced |
|---|---|
| Front bearings damaged, grease washed out | Progressive wear accelerating toward seizure |
| Rear bearings overheating, near failure | Bearing collapse in service |
| Shaft journals intact | Journal damage from a collapsed bearing set |
| Housing geometry within tolerance | Housing distortion, at which point rebuild is no longer on the table |
| Oil in stator laminations | Ongoing thermal and reliability exposure in the motor |
Four Takeaways From This Job
One. Compressed air quality is a spindle specification
Air quality tends to be treated as a compressor room concern. It is not. Oil in the supply reaches the bearings, the seals, and the motor, and it does so quietly enough that the first evidence is a performance complaint rather than an alarm.
Two. Contamination spreads faster than it appears to
Once grease is washed out of one bearing set, heat and wear accelerate and the contamination keeps travelling. On this spindle it reached the front bearings, the rear bearings, and the stator — three components, one source.
Three. The motor is exposed too
Contamination is usually discussed as a bearing problem. Oil inside the stator laminations is a different category of finding, and it requires dedicated decontamination work that a bearing replacement does not include.
Four. Fixing the spindle is only half the job
A rebuilt spindle returned to an uncorrected air system will follow the same path as the one it replaced. The rebuild restores the machine; correcting the ingression is what keeps it restored. That work belongs to the plant, and it protects every other spindle and pneumatic component on the same supply.