Fafnir2MM214WIDUHSuper Precision Angular Contact Ball Bearing 70x125x24 mm, 15° Contact Angle, Duplex Heavy Preload, 2 Pcs

Product Description

What this part is

A matched pair of Fafnir super-precision angular contact ball bearings, part number 2MM214WI-DUH. Bore is 70 mm, outside diameter 125 mm and each ring width 24 mm, giving an ISO 7214 envelope. Fafnir is the super-precision line of the Timken Company, and the WI family is its spindle-grade angular contact series.

Decoding the designation

In the Fafnir scheme the leading 2 of 2MM sets a 15° contact angle, and a 3MM prefix would set 25°. The MM prefix carries super-precision class P4S, equivalent to ABEC 7 dimensionally with ABEC 9 running accuracy. The absence of a leading 9 in 214 places the bearing in the ISO 72 dimension series rather than the lighter 70 series. WI identifies the super-precision angular contact family. DU is a universally ground duplex pair, and the closing H is heavy preload; L and M are the light and medium steps in the same scheme.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity; the 25° equivalent trades the reverse way. Heavy preload raises axial and radial stiffness and reduces non-repeatable runout under load, at the cost of higher running torque and heat generation, so it suits stiff, moderate-speed spindle positions rather than the highest speed ranges. Universal grinding means either ring face may be paired, so the same two bearings can be arranged back to back, face to face or in tandem and still reach the specified preload.

Quantity and configuration

2 Pcs, supplied as one duplex pair ground for heavy preload. No spacer rings, lock nut or housing are included.

Fitting notes

Universally ground duplex bearings reach their designed preload when the pair is clamped solid against the flush ground faces, without shimming. Arrangement is determined by which faces are brought together, and the ground reference marks on the outer ring locate the intended orientation. Handling is done by the outer ring on a clean surface, since a preloaded super-precision pair records handling damage in its running accuracy.

Interchange guidance

Same-spec equivalents in other schemes are the 7214 C P4 DUH forms: SKF 7214 CD/P4ADGB class, FAG B7214-C-T-P4S-UL and NSK 7214 CTR DUH P4. A 7214 AC or A5 variant is a related size with a 25° or 30° contact angle and a different stiffness and thrust characteristic, not a substitution. 2MM214WI-DUL and 2MM214WI-DUM share the envelope and angle at light and medium preload.