Metric Sizes Sealed

Miniature and Small Metric-Size Bearings – Sealed are precision rolling bearings manufactured to metric dimensions, equipped with contact rubber seals (2RS or RSR configuration) on one or both sides. These seals provide superior protection against moisture, fine dust, and liquid contaminants while retaining lubricant for extended maintenance-free operation. Bore diameters typically range from 3 mm to 12 mm, with outer diameters from 8 mm to 28 mm.

Key Technical Features:

• Seal design: Contact-type rubber seals (typically nitrile rubber NBR for -30°C to +110°C, or fluorocarbon FKM for -20°C to +150°C) bonded to a steel insert. The seal lip makes light contact with the inner ring's ground raceway or a dedicated seal groove, creating an effective barrier against contamination ingress and lubricant leakage.

• Metric size standards: Conforming to ISO 15 and DIN 625 dimensions. Common sealed series include 60 series (e.g., 608-2RS: 8×22×7 mm), 62 series (e.g., 626-2RS: 6×19×6 mm), 63 series (e.g., 633-2RS: 3×13×5 mm), and 69 series (e.g., 696-2RS: 6×15×5 mm). Double-sealed (2RS) bearings are pre-lubricated and sealed for life.

• Precision grades: Typically available in P0 (ABEC 1) through P5 (ABEC 5) . Sealed bearings generally trade minimal torque increase for superior environmental protection compared to open or shielded versions.

• Materials: Chrome steel (52100) rings and balls (Grade 5 or 10) for standard applications; stainless steel (440C) for corrosion resistance; hybrid ceramic (Si₃N₄ balls) for electrical insulation or extreme speeds.

• Lubrication: Factory-filled with high-quality grease (lithium complex, synthetic, or food-grade NSF H1) selected for optimal viscosity, wide temperature range, and long service life. Seals prevent grease escape and contamination ingress, eliminating the need for relubrication.

• Torque characteristics: Sealed bearings exhibit higher starting and running torque than open or shielded versions due to seal lip friction. Typical torque values range from 2–12 g·cm depending on size, seal material, and grease fill. Break-in periods may reduce initial torque by 20–30%.

• Speed capability: Contact seals generate heat at high speeds, reducing maximum RPM compared to open bearings. For miniature sealed bearings, maximum speeds typically range from 15,000–30,000 RPM depending on size and seal design.

• Cage options: Crown-type (ribbon) cages in steel, phenolic resin, or polyamide maintain proper ball spacing and minimize internal friction.

• Environmental protection: Sealed bearings achieve IP52 to IP54 ingress protection ratings, resisting dust, water spray, and washdown conditions. Not suitable for submersion (use specialty sealed bearings for underwater applications).

• Maintenance: Designed as "lubricated-for-life" – no relubrication required or possible. Replace the bearing when end-of-life is reached.

Applications:
Sealed miniature metric bearings are ideal for small electric motors exposed to moisture, food processing equipment (with food-grade grease), medical devices, outdoor power tools, automotive accessories (power window motors, wiper motors), conveyor rollers in dusty environments, marine instrumentation, agricultural sensors, packaging machinery, and office automation equipment. They deliver reliable, maintenance-free operation in challenging conditions where contamination would quickly destroy open bearings.