A turbomolecular pump is the most delicate major component in any high-vacuum system — a rotor spinning at up to 90,000 rpm with clearances measured in tenths of a millimetre. Treated well, a turbo runs for a decade; treated carelessly, it destroys itself in milliseconds. Here is what actually kills turbos, and the operating habits that determine whether yours reaches old age.
The three ways turbos die
- Bearing wear (the natural death). Mechanical-bearing turbos use ceramic ball bearings with grease or oil lubrication; these are wear parts with service intervals of a few years depending on model and duty. Rising vibration, audible noise change, or increasing drive current at constant speed are the early warnings. Magnetically levitated turbos eliminate this failure mode entirely — at a price premium — which is why they dominate contamination-critical and continuous-duty installations.
- Sudden inrush / venting at speed (the violent death). Venting a spinning turbo from the wrong port, or a vacuum accident that floods the inlet, applies enormous torque to the rotor. Best case, bearings are damaged; worst case, blades touch stators and the rotor crashes — a total loss. Always vent through the designated vent port, at the manufacturer-specified rate, ideally with the rotor below a safe speed.
- Ingestion (the embarrassing death). Screws, foil scraps, and broken glass from the chamber end up in the blades. A splinter shield or inlet screen costs a little pumping speed and saves the pump; use one on any system where people work above the inlet.
Operating habits that extend life
- Back it properly: run the specified backing pressure; an overloaded turbo running hot ages bearings fast.
- Respect the cooling spec — water-cooled models need real flow, air-cooled models need real airflow; thermal stress is cumulative.
- Balance gas loads: continuous heavy gas throughput (load-lock cycling, process gas) is legitimate duty but shortens bearing intervals — plan service accordingly.
- On mechanical-bearing pumps, follow the lubricant service schedule; a bearing service costs a small fraction of a rotor crash.
- Log drive current and vibration monthly — a slow upward drift at constant speed and pressure is the single best early indicator of bearing distress.
Warning signs to act on now
- New or changing acoustic tone, especially a periodic whine or rumble.
- Drive current rising over weeks at unchanged conditions.
- Longer run-up times to full speed.
- Repeated over-temperature warnings with verified cooling.
A turbo showing these signs should be serviced or swapped on your schedule — not run to failure on the process’s schedule. A crashed rotor frequently writes off the pump; a worn bearing caught early is a routine exchange.
Service exchange vs repair vs refurbished
Manufacturers and independents offer exchange programmes — your worn pump plus a fee for a rebuilt one. For common models (Pfeiffer HiPace, Edwards nEXT, older TMH/TMU and EXT series), the refurbished market often beats exchange pricing, provided the unit comes with a documented test: full-speed run, ultimate pressure, drive current, and vibration data. Insist on those numbers — a turbo that “spins up fine” without data is a gamble.
PLC North stocks bench-tested turbomolecular pumps and matching controllers, each run to full speed and documented before sale. Tell us your flange size, pumping speed, and backing arrangement and we will match a tested unit from stock. Browse our tested vacuum pumps.