A bonded PTFE or MoS2 film puts a low-friction solid lubricant exactly where the sliding happens — which is how a bearing runs dry, or survives a start-up before the oil arrives.
| Thickness | 5–15 µm (typically 8–12 µm) |
|---|---|
| Friction | 0.05–0.15 depending on formulation and load |
| Max service temperature | 200 °C epoxy binder · 260 °C polyimide binder |
| Cure temperature | 150–200 °C for epoxy systems, 230–260 °C for polyimide |
| Effect on dimension | Adds thickness — mask or grind functional surfaces |
| Load capacity | Moderate — a film, not a bearing material |
| Typical use | Dry running, start-up protection, stick-slip elimination, low-torque seals |
PTFE works by transferring a thin film of itself onto the counterface, so the sliding pair becomes PTFE-on-PTFE — two low-energy surfaces. MoS2 works because its crystal structure is layered: sheets slide over each other with weak van der Waals bonds, like graphite but without needing humidity. MoS2 performs better in vacuum and at higher load; PTFE performs better against soft counterfaces and in chemical duty.
Most bearing coatings are not pure PTFE or pure MoS2. They are formulations with a binder, often pigmented, sometimes with graphite or antimony compounds added. The formulation and the cure schedule decide the performance, which is why two “PTFE coatings” can differ by a factor in wear life.
| Property | PTFE dry film | MoS2 dry film | DLC |
|---|---|---|---|
| Thickness | 5–15 µm | 5–15 µm | 1–3 µm |
| Friction | 0.05–0.15 | 0.04–0.12 | 0.05–0.15 |
| Max temp | 200–260 °C (binder) | 200–260 °C (binder) | ≈300 °C |
| Vacuum | Good | Excellent | Excellent |
| Humidity | Good | Poor — MoS2 oxidises | Good |
| Best for | General dry running | High load, vacuum | Wear resistance, thin film |
The strategy this coating belongs to.
Read →Coated seal lips reduce drag and stick-slip.
Read →Thin section, marginal lubrication, high contact pressure.
Read →When wear resistance matters more than friction.
Read →For a limited duty, yes. The film is sacrificial, so life depends on load, speed and how much sliding there is. It is not a permanent dry-running solution in the way a PEEK or ceramic bearing is.
That is the loaded zone. The film has worn through where the contact pressure is highest — either the PV was underestimated or the film was too thin for the load. A thicker film or a different formulation is the fix.
It can. A sealed or pre-greased bearing cannot survive a 200 °C cure, so coating is done before assembly and greasing. Plan the process sequence accordingly.
MoS2. PTFE performs well in vacuum too, but MoS2 has better load capacity there and does not suffer from the outgassing that some PTFE formulations show.
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