As emerging engineering plastics, PEEK and PI have proven to possess the best mechanical strength, dimensional stability and high‑temperature resistance among all known engineering plastics. PEEK has a continuous service temperature up to 260 °C, while PI reaches as high as 300 °C for long‑term operation. Both feature excellent corrosion resistance; only concentrated sulfuric acid can dissolve and degrade them. They can operate reliably under moderately corrosive acid‑alkali environments. Therefore, they are commonly used for bearings requiring precision rotation under relatively harsh conditions. Their main disadvantage is the high material cost, which leads to higher application costs. Typically, inner and outer rings are made of PEEK or PI; cage materials include PTFE, PEEK or PI; balls are generally ZrO₂ or Si₃N₄ ceramic balls.