FafnirAngular Contact Ball Bearing – Straight Bore, 30 mm ID, 55 mm OD, 13 mm Width, Open, 25° Contact Angle, Light Preload, Matched Pair

Product Description

What this part is

Fafnir 3MM9106WO-CR-DUL super precision angular contact ball bearings, supplied as a factory-matched back-to-back pair. Series: 9100. Base Number: 9106. Bore Diameter: 30 mm. Outside Diameter: 55 mm. Overall Width: 13 mm per bearing. Contact Angle: 25°. Precision Class: ABEC 7 / P4. Cage Material: Phenolic. Rolling Elements: Ball. Bore Type: Straight. Closure Type: Open. Number Of Rows: 1 per bearing. Preload: Light. Mounting Arrangement: Back-to-back (DUL). Internal Clearance: N/A. Unit Quantity: 2 Pcs.

Decoding the designation

3MM — Fafnir super precision execution at a 25° contact angle, built to ISO P4S.

9106 — 9100 dimension series at a 30 mm bore. The ISO equivalent is 7006.

CR — phenolic cage.

DUL — two bearings universally ground as a matched set, mounted back to back, at light preload.

What these specs mean in practice

Contact Angle: 25°. A 25° angle carries more thrust and gives higher axial rigidity than a 15° bearing on the same 30 x 55 x 13 mm envelope, at a lower speed ceiling.

Cage Material: Phenolic. Fabric-base phenolic is light and low in inertia, so the cage tolerates rapid acceleration and reversal, and the material holds oil in its own structure.

Preload: Light. Mounting Arrangement: Back-to-back (DUL). A back-to-back pair takes thrust in both directions from one location and resists moment loading; light preload keeps running heat down.

Precision Class: ABEC 7 / P4. Running accuracy at this class holds shaft position to a few microns.

Quantity and configuration

Unit Quantity: 2 Pcs. One factory-matched DUL pair, ground to run together back to back at light preload.

Interchange guidance

The ISO designation for this envelope is 7006 at P4 precision. A matched pair from another maker interchanges where the contact angle is 25°, the precision class is P4 or P4S, the preload is light and the arrangement is back to back. A 15° 7006 fits the same 30 x 55 x 13 mm seat and is listed as a related size rather than an interchange.