Polymer bearings are light, quiet, corrosion-free and need little or no lubrication. They also carry a fraction of the load of a steel bearing and change dimension with temperature and moisture.
| Highest temperature | PEEK at 250 °C continuous; PTFE at 260 °C |
|---|---|
| Lowest friction | PTFE, μ ≈ 0.04–0.10 |
| Best dimensional stability | POM — low moisture absorption, machinable to tight tolerance |
| Load capacity | Typically 5–15% of a steel bearing of the same size |
| Cost vs 52100 | PA66 ≈ 1.2× · POM ≈ 1.5× · PTFE ≈ 4× · PEEK ≈ 5–8× |
The engineering question with polymers is never 'is it strong enough' in the abstract — it is 'what is the PV limit at this speed and this temperature'. Polymer bearings are rated on pressure × velocity, and both terms fall as temperature rises. A POM bearing that runs for years at 0.5 MPa and 0.1 m/s can fail in weeks at 1.5 MPa and 0.5 m/s.
Moisture is the second trap. PA66 absorbs 1.5–2.5% water, which swells the part and closes the clearance; POM absorbs a tenth of that. In a wet plant, POM or PEEK hold their fits and nylon does not.
250 °C, chemical resistant, self-lubricating — the high-performance polymer.
Read →Quiet, stable, machinable — the light-duty default.
Read →Cheap, tough, moisture-sensitive — economy light duty.
Read →The lowest friction of any solid, at very low load.
Read →Many can, which is their main advantage in food, cleanroom and textile machinery. The trade-off is a lower PV limit and a shorter life than a lubricated steel bearing. Where water is present it often acts as the lubricant and coolant at the same time.
Moisture absorption swells the material and closes the running clearance, and UV degrades the surface. POM or PEEK in the same position holds its clearance.
Yes — 6000, 6200 and 6800 series in POM, PA66 and PEEK are stocked in the same boundary dimensions as steel, which makes them drop-in for light-duty replacement.
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