Tribosyn Unitemp 500
Why High-Speed Bearings Are So Demanding
A rolling element bearing is one of the most elegant devices ever built. Hardened steel balls or rollers separated by a cage, running between an inner and outer race, riding on a film of lubricant thinner than a sheet of paper. When it works, it works beautifully. When it fails, it usually does so catastrophically.
The engineering challenge scales sharply with speed. At 50,000 rpm in a gas turbine accessory gearbox, or at a Dn value above one million in a precision machine tool spindle, the lubricant is being asked to do several things simultaneously: maintain a load-bearing film between surfaces sliding past each other at tens of meters per second, carry heat out of the contact zone, resist being thrown clear by centrifugal force, and keep all of the above functioning across a temperature regime that can span more than 200°C.
Most greases are designed for the middle of that range. At cold startup, they turn to wax, and the bearing stalls. At high soak temperatures, they oxidize, phase separate, and leave the contact dry. This is the engineering problem Tribosyn Unitemp 500 was built to solve.
A bearing grease does not fail in the middle of its service life — it fails at the edges. Performance at temperature extremes and stability over time are what separate a precision-grade grease from a general-purpose one.
The Tribology: Dn, Channeling, and EHL
Three concepts define what a bearing grease has to do at speed. They are worth understanding because they drive every design decision in Unitemp 500.
Dn value. Dn is simply the bearing bore diameter in millimeters multiplied by shaft rpm. It is the standard way engineers quantify how hard a bearing is working. A Dn of 500,000 is ordinary industrial service. A Dn of 1,000,000 is the threshold above which most greases begin to lose their film. Aerospace mainshaft bearings routinely operate at Dn values of 2 to 3 million, and precision spindles push even higher. Unitemp 500 is formulated for service at and above Dn ≥ 1 million.
Channeling behavior. When a high-speed bearing first starts running, the grease is thrown outward by centrifugal force. A well-designed bearing grease does not resist this — it allows itself to be pushed into the bearing's cavity walls and stays there, bleeding just enough oil back into the raceway to keep the contact lubricated. This is called channeling, and it is what keeps churning losses and operating temperatures under control. A grease that refuses to channel will be endlessly re-worked by the rolling elements, generating heat and degrading rapidly. Unitemp 500 is engineered to be rheologically channeling, which is why it runs cool at high Dn.
Elastohydrodynamic lubrication (EHL). Inside the rolling contact itself, the pressure is extreme — hundreds of thousands of PSI. Under that pressure, the base oil momentarily stiffens into a quasi-solid film that separates the rolling element from the race. The film is on the order of a tenth of a micron thick. Whether it forms at all depends on the viscosity of the base oil at operating temperature, and whether it persists depends on the oil's oxidative stability. Unitemp 500 uses a synthetic ester base oil with a viscosity index of 142 and a flash point of 290°C.
What Makes Unitemp 500 Different
Plenty of greases advertise a wide temperature range. Far fewer hold up to precision bearing service across the full range in real machinery. Unitemp 500 earns its place in aerospace and defense programs because of how it is built:
| ✓ Synthetic ester base oil — high VI (142), high flash point (290°C), low pour (−56°C) | ✓ Sodium myristate thickener — proven chemistry for clean channeling at high Dn |
| ✓ −54 to 175°C service range — single grease for cold soak through full operating soak | ✓ Rheologically channeling — low churning losses, low operating temperature rise |
| ✓ PDSC at 210°C > 120 minutes — thermo-oxidative stability measured, not estimated | ✓ Boundary-layer anti-wear additives — 0.61 mm Four Ball wear scar at standard conditions |
| ✓ NLGI Grade 1 — pumpable and channeling, but firm enough to stay where it is placed | |
Mineral oils thin out dramatically at high temperatures and wax at low temperatures. PAO synthetic hydrocarbons are better but have modest solvency for additives. Synthetic esters deliver both: a viscosity index well above 140, so the oil does not thin excessively at soak temperature, and natural polarity that keeps additives in solution and lets the film wet metal surfaces aggressively.
Measured Properties
The values below are actual measured characteristics of Unitemp 500 as produced — not nominal targets. Use these numbers directly in bearing analysis, system modeling, and procurement specifications.
Target Applications
Unitemp 500 is in service across a range of precision bearing applications where a single grease must cover the full duty cycle — cold soak, startup, and sustained high-speed running.
| ✓ High-Dn precision rolling element bearings (Dn ≥ 1 million) | ✓ Aerospace and defense bearing lubrication |
| ✓ Machine tool spindles and precision industrial bearings | ✓ Wide-temperature-range industrial equipment |
| ✓ Cold-climate and low-temperature operating environments | ✓ Long-life sealed-for-life bearing assemblies |
Ordering & Available Formats
Unitemp 500 is available in standard formats from bench-scale evaluation volumes through production supply. Non-standard packaging and bulk quantities are available on request.
Non-standard quantities, alternative packaging formats, or bulk supply for production programs are all available. Reach out to TS&E directly — the team is used to working with engineers who have specific requirements.
Safety & Handling
Unitemp 500 is designed for normal industrial handling. No specialized personal protective equipment is required for routine use at ambient temperatures beyond standard nitrile or PVC gloves and safety glasses.
At the elevated temperatures encountered in operating bearings, ensure adequate ventilation where grease residues could generate vapor or smoke. As with any specialty lubricant, consult the Safety Data Sheet before first use or before introducing the product into a new process environment.
Writing a Specification
The properties in this document are typical measured values — an excellent starting point for bearing design evaluation and product qualification. They are not a substitute for a formal procurement specification with defined acceptance limits.
For applications that require tight tolerances, qualification testing, lot traceability, or conformance to aerospace or defense specifications, TS&E can assist in building a specification matched to the end-user requirements. Early-stage conversations are welcome before a formal purchase decision is made.
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