Fafnir2MM9308WIDUMAngular Contact Ball Bearing – Straight Bore, 40 mm ID, 62 mm OD, 12 mm Width, Open, 15° Contact Angle, Medium Preload.

Product Description

What this part is

Fafnir 2MM9308WI-SUM super-precision angular contact spindle ball bearing, built by The Timken Company. Series: 9300WI. Bore: 40 mm. Outside Diameter: 62 mm. Bearing Width: 12 mm. Total Width: 12 mm. Contact Angle: 15°. Precision Rating: ISO P4S (ABEC 7/9). Preload: Medium. Cage Type: CR – Phenolic Outer Land Riding Cage. Cage Material: Phenolic. Rolling Elements: steel balls. Bore Type: Straight. Closure Type: Open. Number Of Rows: 1. Design Units: Metric. Timken’s world part number for this bearing is 71908C-T-P4S-SUM.

Decoding the designation

The 2MM prefix gives a 15° contact angle and ISO P4S accuracy. 9308 in the 9300WI series is the ISO 71908 envelope. WI denotes a low shoulder on both rings. CR is the phenolic outer-land-riding cage. SU marks a single universally ground bearing, and the trailing M sets medium preload when it is mounted against a mate.

What these specs mean in practice

Dynamic Radial Load Rating (C1): 16,000 N (3,600 lbf). C1 ISO Dynamic Radial Rating per row: 14,500 N (3,270 lbf). Static Radial Load Rating (C0): 11,700 N (2,640 lbf). Limiting Speed – Grease: 22,400 rpm. Limiting Speed – Oil: 44,800 rpm. A 15° contact angle favours speed and radial stiffness over thrust capacity. Medium preload raises axial and radial rigidity above the light grade and suits spindles where cut accuracy matters more than the last few thousand rpm.

Quantity and configuration

Unit Quantity: 1 Pc. Arrangement / Configuration: Single universally ground. Rows per Set: Single. Universal grinding means any two of these bearings mount together as a matched set in any orientation and arrive at the published preload.

Mounting data

Max Shaft Fillet Radius: 0.6 mm (0.024 in). Outer Ring To Clear Radius: 0.6 mm (0.024 in). Shaft Backing Shoulder Diameter: 44.6 mm (1.760 in). Housing Backing Shoulder Diameter: 57.9 mm (2.280 in).

Interchange guidance

Cross-references: 71908C-T-P4S-SUM, SKF 71908 CDGB/P4A, FAG B71908-C-T-P4S-UL, NSK 7908CTYNSUMP4. Searchable forms of the designation: 2MM9308WISUM, 2MM9308WI-SUM, 2MM 9308 WI CR SUM, 7908C.