Enabling Ultra-Stable Bearing Performance: Design of a Self-Lubricating PI Composite Retainer

To address challenges such as temperature rise, operational instability, and premature failure in rolling bearings caused by retainer friction, this study designed and developed a high-performance polyimide (PI)-based composite self-lubricating retainer to enable “ultra-stable” bearing operation. Both solid and oil-porous self-lubricating retainers were fabricated through material composition and structural design. Systematic tests under controlled load and speed conditions were conducted to compare their temperature rise behavior and wear morphology. The results demonstrated that the temperature rise in the YSU-PI1 bearing with a solid retainer decreased by approximately 57% compared to a conventional bearing. The YSU-PA2 bearing with an oil-porous retainer exhibited a further improvement in thermal performance. Notably, under high-speed conditions, the equilibrium temperature of the YSU-PA2 bearing was lower than that under low-speed conditions, confirming a centrifugal-force-driven self-regulating oil-supply mechanism. Wear surface analysis revealed that the porous structure promoted the formation of a continuous and uniform transfer film, effectively mitigating wear and pitting. This study successfully integrates “material–structure–function” innovation. The oil-porous PI-based composite retainer transforms centrifugal force—typically considered detrimental—into a beneficial lubrication mechanism, effectively suppressing temperature rise and enabling “ultra-stable operation”. These findings provide crucial theoretical and technical support for developing bearings for high-end equipment.