Fafnir2MM9311WI CR DULSuper Precision Angular Contact Ball Bearing – Straight Bore, 55 mm ID, 80 mm OD, 13 mm Width, Open, 15° Contact Angle, Light Preload, Matched Duplex Pair

Product Description

What this part is:

Fafnir 2MM9311WI-CR-DUL super precision angular contact ball bearing, supplied as a factory-matched duplex pair. Bore Diameter: 55 mm. Outside Diameter: 80 mm. Overall Width: 13 mm. Contact Angle: 15°. Precision Class: ABEC 7/9 / P4S. Cage Material: Phenolic. Rolling Elements: Ball. Bearing Material: Bearing Steel. Bore Type: Straight. Closure Type: Open. Number Of Rows: 1. Series: 2MM9300. Base Number: 2MM9311WI. GTIN: 087796206076.

Decoding the designation:

2MM — 15° contact angle, Fafnir super precision range.

9311 — 9300WI series, ISO 719-series envelope, 55 mm bore.

WI — low shoulder on both rings.

CR — phenolic cage.

DU — duplex set, universally ground for flush faces.

L — light preload.

What these specs mean in practice:

Dynamic Load Rating: 21,800 N. Static Load Rating: 18,500 N. A 15° contact angle favours speed and radial stiffness, carrying less thrust per row than a 25° execution and running cooler at the same shaft speed.

Limiting Speed: 16,600 rpm grease; 33,200 rpm oil. Lubricant: grease or oil. The phenolic cage is light and damps cage chatter, which is what supports those speeds on a 55 mm bore.

Precision Class: ABEC 7/9 / P4S gives tight raceway and face runout, for spindle work where shaft position has to hold under load. Internal Clearance: N/A — the set runs under preload.

Mounting data:

Shaft Backing Shoulder Diameter: 60.4 mm (2.380 in). Housing Backing Shoulder Diameter: 75.2 mm (2.960 in). Maximum housing fillet radius the bearing corners clear: 1 mm (0.039 in).

Quantity and configuration:

Unit Quantity: 2 Pcs. Arrangement: duplex pair, universally ground, light preload. Preload: Light.

Interchange guidance:

Super precision executions on the same 55 x 80 x 13 mm envelope at 15°: SKF 71911 CD/P4ADGA, FAG B71911-C-T-P4S-DUL, NSK 7911CTRDULP4, NTN 7911UCDB/GNP4, RHP 7911CTDULP4, IBC 71911-C-TPA-P4-DUL and Koyo 7911CTRDULP4. Searchable forms of the Fafnir number: 2MM9311WICRDUL, 2MM-9311-WI-CR-DUL, 2MM 9311 WI CR DUL. Timken world part number: 71911C-T-P4S-DUL.