April 21,2026
Retainer / Cage
Selection & Application:
General industrial bearings (deep groove ball bearings, cylindrical roller bearings) – low cost, high volume.
Moderate temperature range (-40°C to +150°C), insensitive to most lubricants.
Suitable for low to medium speed, moderate load – not for very high speed because pressed construction has poor balance.
Precaution:
Surface zinc or phosphate plated – limited rust resistance.
Relatively large clearance between rolling elements and pocket – can cause noise and friction.
At high speed, centrifugal force may cause deformation or fracture.
Load: centrifugal and inertial force can be calculated using bearing dynamic, but stiffness scatter of pressed parts makes results uncertain.
Speed: limiting speed from bearing catalogue can be used, but individual cage fatigue life cannot be accurately calculated.
Life: no standard cage life model – usually assumed same as calculated bearing life (in reality often shorter).
Experience count:
In high‑speed application, if measured temperature rise exceeds 70°C, switch to a machined cage.
Temperature: material property vs. temperature curve are openly available.
Hand‑rotating noise: “clicking” sound indicate pocket wear – shorten relubrication interval.
Inspection: red wear debris on cage surface indicates insufficient lubrication or deformation.
Selection & Application:
Small‑to‑medium bearings, home appliance, automotive parts (low noise, low cost).
Allows slight contact between rolling elements and cage without generating metallic wear particles.
Some elasticity, not highly sensitive to contamination.
Precaution:
Strict temperature limit: -30°C to +110°C (short‑term 120°C).
Hygroscopic – dimensional change (0.2-0.5% size increase per 1% moisture uptake) may cause interference.
Not for vacuum (outgassing) or strong acids/alkali.
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 limit - 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 crumble or melting smell appear, stop immediately.
Empirical life: under rated condition, usually no more than 15,000 hours - mandatory replacement.
Experience count:
Pre‑soak cage in target humidity and temperature for 24 hours, measure pocket dimensional change.
Cage material must be compatible with the lubricant.
Selection & Application:
Very high speed bearings (precision machine tool spindle, angular contact ball bearings).
Low density, low centrifugal force, flexible.
Typical grade: M208, M209 (FAG), BX (SKF).
Precaution:
Not water‑resistant, not high‑temperature resistant (long‑term <110°C).
Brittle - can fracture under shock load.
Lubricant must be compatible with phenolic resin (avoid certain synthetic oil containing ester).
Manufacturer provide speed limit curve (dn value chart) - they can be used for calculation.
No standard life model - typically estimate as half the designed bearing life.
Experience count:
Run‑in: 4 hours at 20% rated speed, check for powder release.
Sudden vibration increase (acceleration >10 g) indicates unstable cage wear.
Correction: multiply calculated speed by 0.9 (oil lubrication) or 0.8 (grease lubrication).
Selection & Application:
Severe environment: high temperature (~250°C), aggressive chemical, oil‑free lubrication.
Medical equipment, semiconductor manufacturing, aerospace bearings.
Low friction, low noise, radiation resistant.
Precaution:
Very high cost (10-20× that of nylon).
Strength drops significantly at high temperature – fibre reinforcement needed.
Lower module than metal – may cause excessive elastic deformation.
Experience count:
Trial run at 120% rated speed for 30 minutes in a simulated environment, check for deformation.
Empirical rule: long‑term operating temperature should be <80% of glass transition temperature (~143°C).
Whitening of cage surface indicates lubricant incompatibility – switch to PFPE oil.
Cage life can be estimated using fracture mechanics model (crack propagation).
Speed limit can be calculated from density and strength value, using FEA + multi-body dynamic.
Selection & Application
High speed, moderate‑to‑heavy load (spindle, high‑speed gearbox, turbocharger).
Naturally low friction against rolling elements.
Good thermal conductivity, helps remove frictional heat.
Precaution:
High cost (cast or machined from solid).
Susceptible to corrosion from certain lubricant additive (active sulphur).
High density (≈8.5 g/cm³) – at very high speed, centrifugal force are significant.
Experience count:
Speed limit can be determined from oil film force between pocket and rolling element.
Temperature effect on strength are openly available.
Dark spot on brass surface after operation indicate lubricant corrosion – change oil type.
Short‑term temperature allowed up to 180°C, but above 150°C check hardness every 500 hours.
Correction factor: multiply calculated limiting speed by 0.85 as practical safety margin.
Selection & Application:
Very large bearings (wind turbine main shaft, rolling mill, slewing ring).
High reliability, impact resistance, wide temperature range (-40°C to +200°C).
Typically riveted or one‑piece construction.
Precaution:
Heavy - high centrifugal force, not suitable for high speed.
Requires anti‑rust treatment (silver, zinc plating, or phosphating).
High machining precision required to avoid rolling element jamming.
Inspection: use borescope to check pocket edge - plastic deformation means increase hardness or enlarge fillet.
Maintenance: check rivet for looseness every 2000 hours.
Experience count:
Correction: actual permissible speed = calculated limiting speed × thermal balance factor (typically 0.8–0.9).
Fatigue life checked at 10⁷ cycles based on material strength.
Selection & Application:
Aero‑engine main shaft, high‑speed compressor.
Lightweight (≈2.7 g/cm³), high specific strength.
Usually hard anodised to improve wear resistance.
Precaution:
Sensitive to fretting wear (once anodised layer is damaged, base metal wears rapidly).
Higher thermal expansion than steel - guide clearance requires special design at high temperature.
Not for alkaline lubricant or seawater environment.
Inspection: anodised layer must not peel - if peeling occurs, replace immediately.
Experience count:
Empirical assembly clearance: at room temperature, guide clearance 0.02-0.04 mm larger than for steel cage.
If vibration spectrum shows half‑frequency whirl, reduce speed by 10% or increase oil flow.
Finite element analysis well established – thermal and centrifugal stresses can be accurately calculated.
Rotordynamic models can predict cage whirl stability.
