Welcome to the MTWB Technical Q&A Center. This page addresses common engineering questions on bearing cage materials, speed limits, thermal management and vibration analysis. Our insights cover brass, steel and PEEK cages, helping you optimize selection and maintenance.
1. Empirical assembly clearance: at room temperature, guide clearance 0.02-0.04 mm larger than for steel cages.
2. If vibration spectrum shows half‑frequency whirl, reduce speed by 10% or increase oil flow.
3. Finite element analysis well established – thermal and centrifugal stresses can be accurately calculated.
4. Rotordynamic models can predict cage whirl stability.
1. Sensitive to fretting wear (once anodised layer is damaged, base metal wears rapidly).
2. Higher thermal expansion than steel - guide clearance requires special design at high temperature.
3. Not for alkaline lubricants or seawater environments.
4. Inspection: anodised layer must not peel - if peeling occurs, replace immediately.
1. Aero‑engine main shafts, high‑speed compressors.
2. Lightweight (≈2.7 g/cm³), high specific strength.
3. Usually hard anodised to improve wear resistance.
1. Correction: actual permissible speed = calculated limiting speed × thermal balance factor (typically 0.8–0.9).
2. Fatigue life checked at 10⁷ cycles based on material strength.
1. Heavy - high centrifugal forces, not suitable for high speed.
2. Requires anti‑rust treatment (silver, zinc plating, or phosphating).
3. High machining precision required to avoid rolling element jamming.
4. Inspection: use borescope to check pocket edges - plastic deformation means increase hardness or enlarge fillet.
5. Maintenance: check rivets for looseness every 2000 hours.
1. Very large bearings (wind turbine main shafts, rolling mills, slewing rings).
2. High reliability, impact resistance, wide temperature range (-40°C to +200°C).
3. Typically riveted or one‑piece construction.
1. Speed limit can be determined from oil film forces between pockets and rolling elements.
2. Temperature effects on strength are openly available.
3. Dark spots on brass surface after operation indicate lubricant corrosion – change oil type.
4. Short‑term temperature allowed up to 180°C, but above 150°C check hardness every 500 hours.
5. Correction factor: multiply calculated limiting speed by 0.85 as practical safety margin.
1. High cost (cast or machined from solid).
2. Susceptible to corrosion from certain lubricant additives (active sulphur).
3. High density (≈8.5 g/cm³) – at very high speeds, centrifugal forces are significant.
1. High speed, moderate‑to‑heavy loads (spindles, high‑speed gearboxes, turbochargers).
2. Naturally low friction against rolling elements.
3. Good thermal conductivity, helps remove frictional heat.
1. 定格速度の120%で30分間、模擬環境にて試運転を行い、変形がないか確認する。
2. 経験則：長期運転温度はガラス転移温度（約143°C）の80%未満に保つこと。
3. ケージ表面の白化は潤滑剤の不適合を示す – PFPEオイルに切り替えること。
4. ケージの寿命は破壊力学モデル（き裂進展）を用いて推定できる。
5. 速度限界は密度と強度の値から、FEA＋マルチボディダイナミクスを用いて算出できる。
1. コストが非常に高い（ナイロンの10〜20倍）。
2. 高温では強度が大幅に低下するため、繊維強化が必要。
3. 金属よりも弾性率が低く、過度な弾性変形を引き起こす可能性がある。
1. 過酷な環境：高温（約250°C）、強力な化学薬品、無給油潤滑。
2. 医療機器、半導体製造、航空宇宙用ベアリング。
3. 低摩擦、低騒音、耐放射線性。
