Timken2MM211WI-DULSuper-Precision Angular Contact Ball Bearing, 55x100x21 mm, 15° Contact Angle, Duplex Light-Preload Set (2 pcs), ABEC 7/9 (P4S)

Product Description

What this part is

Timken Fafnir 2MM211WI DUL super-precision angular contact ball bearings, universally ground duplex set. Bore: 55 mm. Outside Diameter: 100 mm. Width: 21 mm per bearing. Total Width: 42 mm for the set. Contact Angle: 15°. Cage Material: Phenolic. Cage Type: Outer-ring land-riding. Rolling Elements: Steel balls. Precision Class: ABEC 7/9 (ISO P4S). Preload: Light. GTIN: 0087796070608.

Published performance data

Dynamic Load Rating (C1): 58,700 N (13,200 lbf) per bearing. Dynamic Load Rating (C1 ISO, per row): 53,400 N (12,000 lbf). Static Load Rating (C0): 40,000 N (9,000 lbf) per bearing. Limiting Speed: 14,500 rpm grease lubrication, 29,000 rpm oil lubrication. Item Weight: 0.608 kg (1.34 lb) per bearing, 1.216 kg (2.68 lb) for the duplex set.

Mounting data

Shaft Backing Shoulder Diameter: 63.3 mm (2.490 in). Housing Backing Shoulder Diameter: 92.2 mm (3.630 in). Maximum Fillet Radius on the mating shaft or housing: 1.5 mm (0.059 in).

Decoding the designation

2MM — Fafnir super-precision spindle series, ISO P4S tolerance.

211 — 55 mm bore in the 72 dimension series.

WI — angular contact spindle execution.

CR — phenolic outer-ring land-riding cage.

DUL — universally ground duplex pair, light preload.

What these specs mean in practice

A 15° contact angle keeps the load line shallow, which is what lets this bearing run to 14,500 rpm on grease and 29,000 rpm on oil. The phenolic outer-land-riding cage is light and runs against a lubricated land rather than the balls, so it adds very little to the heat budget at those speeds. The light preload sets running accuracy and stiffness at the factory, which is why the pair is bought as a matched unit. Universal grinding means the flush-ground faces let the same two bearings be assembled back-to-back (DB), face-to-face (DF) or in tandem (DT) without shims, and the preload comes out the same in each case.

Quantity and configuration

Unit Quantity: 2 Pcs. A universally ground duplex set of two bearings with a light factory preload. The load ratings above are per bearing; the weight is given both per bearing and for the set.

Interchange guidance

Timken’s world part number for this bearing is 7211C-T-P4S-DUL. The same 55 x 100 x 21 mm envelope is built by FAG as B7211-C-T-P4S and by NSK as 7211CTRDULP4. Match the contact angle, the precision class and the preload class as well as the boundary dimensions. Typical applications are high-speed grinding, milling and boring spindles, jig borers and precision routers.