Inch Sizes Standard Shielded

Miniature and Small Inch-Size Bearings – Standard Shielded are precision rolling bearings manufactured to imperial (inch) dimensions, equipped with metal shields (ZZ configuration) on one or both sides. These shields provide effective protection against larger contaminant particles while maintaining low friction and high-speed capability. Outer diameters typically range from 0.1250 inches (3.175 mm) to 1.0000 inches (25.4 mm).

Key Technical Features:

• Shield design: Non-contact metal shields (typically pressed steel or stainless steel) are crimped into a groove on the outer ring. A narrow annular gap (typically 0.05–0.15 mm) between the shield and inner ring allows minimal friction while blocking airborne dust, fibers, and larger debris.

• Inch size standards: Conforming to ABMA inch-series dimensions, including R, RLS, and F-series. Common shielded versions include R2ZZ, R4ZZ, R6ZZ, and R8ZZ.

• Precision grades: Available from ABEC 1 (P0) for general use to ABEC 7 (P4) and ABEC 9 (P2) for high-precision applications. Shielded miniature inch bearings routinely achieve ABEC 5 or higher.

• 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: Pre-lubricated at factory with high-quality grease (typically lithium-based or synthetic) selected for low torque, wide temperature range (-40°C to +120°C), and long life. Shields retain grease effectively while preventing contamination ingress.

• Torque characteristics: Shielded bearings exhibit slightly higher starting and running torque than open bearings due to grease drag, but significantly lower than sealed versions. Typical torque values range from 0.5–5 g·cm depending on size and grease fill.

• Speed capability: Non-contact shields allow speeds comparable to open bearings (up to 50,000 RPM or higher for small sizes), limited primarily by grease and cage design rather than shield drag.

• Cage options: Crown-type (ribbon) cages in steel, phenolic resin, or polyamide optimize ball spacing and reduce friction.

• Environmental protection: Shields provide protection against dry, fibrous, or larger-particle contamination (typically >50 microns). Not suitable for wet environments or fine dust (use sealed versions instead).

• Maintenance: Shielded bearings are generally non-relubricatable (no grease fittings) and designed for "lubricated-for-life" service in clean to moderately clean environments.

Applications:
Shielded miniature inch bearings are ideal for small electric motors, cooling fans, office automation equipment (printers, scanners, copiers), computer hard disk drives, precision pumps, dental handpieces, model aircraft engines, instrumentation, and robotics joints. They provide an optimal balance of contamination protection, low friction, and high-speed performance in compact assemblies.