FafnirSuper-Precision Angular Contact Ball Bearing – Straight Bore, 40 mm ID, 90 mm OD, 23 mm Width, Open, 25° Contact Angle, Heavy Preload, Phenolic Cage.

Product Description

What this part is

Fafnir 3MM308WICR-SUH super-precision angular contact ball bearing, 300WI series. Brand: Fafnir (Timken). Part Number: 3MM308WICR-SUH. Bore: 40 mm. Outside Diameter: 90 mm. Overall Width: 23 mm. Total Width: 23 mm. Design Units: Metric. Number Of Rows: 1. Rolling Elements: Steel ball. Bore Type: Straight. Closure Type: Open. Bearing Material: Chrome bearing steel. Item Weight: 1.40 lbs.

Decoding the designation

Contact Angle: 25°. Precision Class: P4S. Precision Rating: ABEC 7/9. Cage Material: Phenolic. Cage Type: CR – phenolic outer land riding. Preload: Heavy. Arrangement / Configuration: Single, universally ground. Series: 300WI, carrying the ISO 7308 envelope of 40 x 90 x 23 mm.

Load ratings and speeds

Dynamic Radial Load Rating (C1), per bearing: 57,500 N (12,900 lbf). Dynamic Radial Load Rating (C1 ISO, per row): 52,300 N (11,700 lbf). Static Radial Load Rating (C0), per bearing: 33,800 N (7,600 lbf). Limiting Speed, grease: 15,200 rpm. Limiting Speed, oil: 30,400 rpm.

What these specs mean in practice

A 25° contact angle carries more thrust load and holds the shaft more stiffly along its axis than a 15° bearing on the same envelope. The heavy preload class raises axial and radial stiffness further, which suits a spindle position where deflection under cutting load governs the finish. The 300 series is the heavy section, so a 40 mm shaft carries more load here than it would in a 70- or 72-series bearing. Oil feed doubles the speed ceiling from 15,200 to 30,400 rpm. Internal Clearance: N/A — the bearing is set by preload rather than by clearance.

Mounting data

Shaft Backing Shoulder Diameter: 49.3 mm (1.940 in). Housing Backing Shoulder Diameter: 81.3 mm (3.200 in). Maximum Shaft Fillet Radius: 1.5 mm (0.059 in). Outer Ring “To Clear” Radius: 1.5 mm (0.059 in).

Quantity and configuration

Unit Quantity: 1 Pc. Mounting Arrangement: Universal. Universally ground faces let the bearing be stacked against another piece of the same designation back-to-back, face-to-face or in tandem, producing the heavy preload class directly with no shimming or regrinding.

Interchange guidance

Cross-References: SKF 7308 ACD/P4A, FAG B7308-E-T-P4S-UH, NSK 7308A5, Timken 7308E. Each shares the 40 x 90 x 23 mm envelope and the 25° contact angle. Harmonization Code: 8482.10.50.68.

Designation variants

MPN Variants: 3MM308WICR-SUH, 3MM308WICRSUH, 3MM-308-WI-CR-SUH, 3MM 308 WI CR SUH, 3MM308WICRDUH, 3MM-308-WI-CR-DUH, 7308E-T-DUH-P4, 7308A, 7308A5, 7308ACD, 3MM308WI.