Fafnir2MM9110WIDULSuper-Precision Angular Contact Ball Bearing 50x80x16 mm 15 Degree Duplex Matched Pair Light Preload Phenolic Cage

Product Description

What this part is

A super-precision angular contact ball bearing in the Fafnir WI spindle series, supplied as a factory-matched duplex pair. Bore 50 mm, outside diameter 80 mm, width 16 mm per bearing.

Decoding the designation

2MM — 15° contact angle in the Fafnir scheme. A 3MM prefix on the same envelope would be 25°.
9110 — the leading 9 marks the ISO 70 light series; the size corresponds to a 7010, at 50 mm bore and 80 mm outside diameter.
WI — super-precision spindle bearing series.
CR — phenolic cage, riding on the outer ring land.
DUL — duplex universal pair, light preload.
The MM prefix carries the P4S class: ABEC 7 dimensional tolerances with ABEC 9 running accuracy.

What these specs mean in practice

A 15° contact angle is the high-speed end of the angular contact range, with less centrifugal ball loading and lower heat than a 25° bearing of the same envelope, and proportionally less thrust capacity. An outer-land-riding phenolic cage is guided by the stationary ring rather than by the balls, which keeps cage motion stable at high speed and lets the cage carry a small reservoir of oil in the fabric. P4S running accuracy at ABEC 9 is the tightest runout grade Fafnir published for this series.

Quantity and configuration

2 Pcs — one matched duplex pair. Universal grinding allows the pair to be assembled back-to-back, face-to-face or in tandem.

Fitting notes

The preload is ground into the ring faces and is realised only when both inner rings and both outer rings are clamped solidly against their seats. Alignment marks on the outer ring faces set the intended arrangement.

Interchange guidance

The ISO shorthand for this size and angle is 7010 C. Same-envelope bearings at a 25° contact angle, such as a 3MM9110WI, or at medium or heavy preload, are related sizes rather than interchanges. A 2MM210WI is the heavier 72-series section on the same 50 mm bore, not a substitute.