Greases, oils and tribology: what to use on technopolymers
A "universal" grease taken off the workshop shelf can destroy a technopolymer gear in a few hours. Not from excess lubrication, but from chemical incompatibility. Knowing which lubricants to choose, and which to avoid, is the difference between a transmission that lasts years and one that cracks without warning.
Are technopolymers self-lubricating?
POM-C and PA6 have a contained dry friction coefficient, which allows operation without external lubrication in many light applications. With a compatible lubricant, friction is reduced further, sharply. Less friction means less heat generated, less wear and a sensibly longer service life.
For technopolymer gears, Molykote G-4500 is the reference lubricant we use. At equal torque, regime and operating conditions, the service life in hours increases significantly relative to dry running. The torque values reported in the catalog tables refer to dry operation. Consider this figure as the starting baseline, not the upper limit.
When lubricating pays off anyway
Even where dry running is technically possible, a small quantity of compatible lubricant extends the gear's service life by 50-100%. The cost/benefit ratio is almost always favorable.
Recommended lubricants: PTFE, silicone, lithium
For technopolymers there are three main families of compatible lubricants. PTFE-based greases (polytetrafluoroethylene, known as Teflon) are the first choice: chemically inert, temperature-stable, compatible with POM-C, PA6 and PK. Silicone greases are equally compatible and particularly suited to low-temperature applications or polymers sensitive to solvents. Lithium soaps are a good alternative for standard industrial uses, economical and widely available.
| Lubricant family | POM compatibility | PA6 compatibility | Usage notes |
|---|---|---|---|
| PTFE grease (Teflon) | Excellent | Excellent | Universal first choice |
| Silicone grease | Excellent | Excellent | Excellent at low temperatures |
| Lithium soap | Good | Good | Economical, general-purpose |
| Aromatic hydrocarbons | PROHIBITED | Not recommended | Stress cracking on POM |
| Strong EP additives | PROHIBITED | Not recommended | Chemical attack |
Lubricants to avoid
Some lubricants excellent on metal gears are incompatible with technopolymers. Greases containing aromatic hydrocarbons cause stress cracking: the polymer develops surface micro-cracks that propagate under load up to brittle fracture. POM-C is particularly sensitive to this damage mechanism.
EP (Extreme Pressure) additives, formulated to resist metal-to-metal contacts at very high pressure, can chemically attack polymers. Before using any unverified lubricant on a technopolymer gear, check the product's datasheet.
Don't use "universal" lubricants or general-maintenance greases without having verified compatibility with the material. A wrong lubricant can compromise the gear in a few hours, without visible signals before fracture.
How much and how often to lubricate
The quantity of grease to apply is modest: a few grams distributed uniformly on the teeth. Over-lubricating brings no advantages: the excess grease accumulates in the cavities, traps dirt particles and can cause localized overheating.
For re-lubrication intervals, as a starting point consider every 1,000-3,000 hours of operation under standard conditions. Increase the frequency in dusty or high-temperature environments.
If you have a lubricant in stock in the workshop and aren't sure of compatibility with your gear's technopolymer, write to the technical office before using it. We verify the datasheet together and indicate the right alternative.