·  Heavy load, low to medium speed (rolling mills, gearboxes, large motors).

·  Pure radial load or minor axial load (with ribs).

·  Reverse‑calculate limit from measured vibration and temperature rise curve.

·  Vibration threshold: RMS velocity >2.5 mm/s indicates excessive preload or incorrect clearance.

·  Temperature: use cooling slope after shut‑down to judge over/under‑lubrication.

·  Contamination: introduce a_ISO factor based on oil cleanliness.

·  Mounting interference: heat inner ring; measured reduction in clearance should be within ±15% of calculated value.

·  Material fatigue scatter 0.8-1.2 is typically normal.

·  Load, speed, life, temperature all have classical formulas.

·  For examples, ISO 281, SKF life model

· Sensitive to contamination (particles cause early spalling).

· Reliable lubrication required to prevent contact fatigue.

· General industrial motors, pumps, gearboxes, wheel bearings (deep groove ball bearings).

· Moderate load, high speed, low cost.

· Life correction: microscopic defects in ceramics cause scatter; empirical factor 0.7–0.9 of calculated life (aerospace grade = 1.0).

· Speed correction: lab calculation should be increased 10-15% as safety margin, then fine‑tuned by measuring vibration.

· Lubrication experience: minimum λ for grease lubrication should be lowered to 1.0 (steel requires 1.5); observe running‑in temperature rise.

· Load: Hertzian contact stress; allowable stress for ceramic (~3000-3500 MPa) higher than bearing steel (~2500–2800 MPa), use ISO 281 or ceramic-specific contact models.

· Speed: Centrifugal and gyroscopic moment calculations with ceramic correction factors give precise limiting speed.

· Life: ISO 281 includes a_cer factor, or use hybrid bearing life model (accounting for higher elasticity modulus).

· Temperature: Thermal balance calculation reliable; include correction due to low thermal conductivity (temperature difference between inner ring and ball).

· Sensitive to impact loads (brittle material), avoid severe shocks.

· Low thermal expansion coefficient - when assembled with steel rings, cold clearance must be controlled (otherwise interference at high temperature).

· Cost is 5-10× that of steel balls - justify economically.

· High-speed spindles, aerospace engines, machine tool spindles - low density (≈3.2 g/cm³ vs. 7.8 for steel) reduces centrifugal force and heat, enabling higher speeds (dn > 2×10⁶).

· Vacuum, oil‑free, or corrosive environments - self‑lubricating, corrosion resistant, electrically insulating (prevents fluting damage).

· Hybrid ceramic bearings (ceramic balls + steel rings) - high hardness and low friction.

Precision plastic materials (POM and PA) has excellent mechanical strength, wearing resistance, self-lubricating and low friction characteristic. The inner and outer rings of a precision plastic bearing are usually made from POM, the cage is PA and balls are glass, stainless steel or ceramic.  The main advantages of precision plastic materials are light weight, low maintenance and cost-effective.

Ceramic materials (Zro2, Si3N4) has the characteristics of higher temperature resistance, corrosion resistance, wear resistance，non-magnetic，non-electrical conducting，self- lubricating，lower friction than other metal bearing materials.  With a good choice of cage materials for example PTFE, Nylon 66, Polyetherimide Ammonia, Zirconia, Stainless Steel or Special Aviation Aluminum, ceramic bearing can be a perfect solution to demanding application for longer bearing life, higher speed or operating temperature up to 250 ℃.