Miniatures & Small Metric Sizes Bearings are precision rolling components manufactured to international metric (ISO) dimensions, with bore diameters typically ranging from 1 mm to 12 mm and outer diameters from 3 mm to 30 mm. These bearings are designed for compact mechanisms requiring high rotational accuracy, low friction, and reliable performance in space-constrained applications across global industrial standards.
Key Technical Features:
Metric dimension standards: Conforming to ISO 15 and DIN 625 standards. Common series include 68 series (e.g., 681: 1×3×1 mm), 69 series (e.g., 694: 4×11×4 mm), 60 series (e.g., 608: 8×22×7 mm), 62 series (e.g., 626: 6×19×6 mm), and 63 series (e.g., 623: 3×10×4 mm). MR series available for ultra-miniature applications.
Configurations available: Offered in open, shielded (ZZ) , and sealed (2RS/RSR) versions. Open types provide lowest friction and highest speed; shielded types balance protection and low torque; sealed types offer maximum contamination resistance and lubricant retention for maintenance-free operation.
Precision grades: Available from P0 (ABEC 1) for general use through P5 (ABEC 5) , P4 (ABEC 7) , and P2 (ABEC 9) for high-precision instrumentation and high-speed applications. Miniature metric bearings routinely achieve P5 and higher tolerances.
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, higher speed capability, and extended fatigue life.
Internal design: Deep groove geometry provides balanced radial and axial load capacity. Optimized ball complement and raceway surface finish (Ra ≤ 0.02 μm) minimize friction, vibration, and noise.
Cage options: Crown-type (ribbon) cages in steel, phenolic resin, or polyamide maintain proper ball spacing. Full-complement designs available for maximum load capacity in oscillating or low-speed applications.
Lubrication: Pre-lubricated with high-quality grease (lithium, synthetic, or food-grade NSF H1) for sealed/shielded versions. Open bearings accept oil, oil-mist, or dry lubricants for high-speed or cleanroom environments.
Torque characteristics: Starting and running torque as low as 0.1 g·cm for open miniature bearings; sealed versions range from 2–12 g·cm depending on size, seal material, and grease fill.
Speed capability: Open and shielded versions achieve speeds exceeding 50,000–100,000 RPM for the smallest sizes (1–3 mm bore); sealed versions typically limited to 15,000–30,000 RPM due to seal friction and heat generation.
Applications:
Miniature metric bearings are essential for instrumentation, gyroscopes, potentiometers, encoders, flow meters, dental handpieces (400,000+ RPM), micro-turbines, miniature pumps, aerospace actuators, optical positioning stages, semiconductor manufacturing equipment, medical devices, small electric motors, cooling fans, and robotics joints. These precision components deliver reliable, low-friction rotation in the most demanding micro-mechanical systems worldwide.
