· Strict temperature limit: -30°C to +110°C (short‑term 120°C).

· Hygroscopic – dimensional changes (0.2-0.5% size increase per 1% moisture uptake) may cause interference.

· Not for vacuum (outgassing) or strong acids/alkalis.

· No widely accepted fatigue life model; moisture absorption and ageing make calculations unreliable.

· Centrifugal deformation can be estimated, but creep cannot be quantified.

· Speed/temperature can only be assessed using material limits - precise life prediction not possible.

· Life: the cage is often the “weakest link” – schedule first inspection at 30-50% of calculated bearing life.

· Field judgement: if cage crumbles or melting smell appears, stop immediately.

· Empirical life: under rated conditions, usually no more than 15,000 hours - mandatory replacement.