Fafnir2MM9509WICRDULSuper Precision Angular Contact Ball Bearing Matched Duplex Pair 45 x 80 x 18 mm 15 Degree ABEC 7 Light Preload

Product Description

What this part is

A matched duplex pair of super-precision angular contact ball bearings in the Fafnir 9500WI spindle series, each 45 mm bore × 80 mm outside diameter × 18 mm width.

Decoding the designation

2MM — 15° contact angle, Fafnir super-precision spindle bearing.
9509 — 9500 dimension series, bore code 09, giving a 45 mm bore.
WI — spindle angular contact ball bearing, universally ground faces.
CR — phenolic cage riding on the outer ring land.
DU — duplex, a factory-matched set of two.
L — light preload.

The MM prefix on a Fafnir spindle bearing carries P4S tolerances — ABEC 7 dimensional accuracy with ABEC 9 running accuracy.

What these specs mean in practice

A 15° contact angle biases the bearing toward speed and radial rigidity, and carries less thrust than a 25° bearing in the same envelope. Light preload keeps contact loads and heat generation low, which suits high-speed spindles where thermal growth rather than stiffness sets the limit. The 9500WI series sits between the ISO 7000 and 7200 envelopes, giving a heavier ball complement than a 9100WI of the same bore in a smaller outside diameter than a 200WI. Phenolic places the working temperature ceiling near 120 °C.

Published specifications

Bore: 45 mm (1.7717 in)
Outside diameter: 80 mm (3.1496 in)
Width per bearing: 18 mm (0.7087 in)
Stack width, pair: 36 mm (1.4173 in)
Contact angle: 15°
Precision class: ABEC 7 / ISO P4S
Preload: light (L)
Rows per bearing: 1
Cage: phenolic, outer-land-riding
Rolling elements: steel balls
Closure: open, both faces

Quantity and configuration

Matched duplex pair, 2 Pcs. The two bearings are ground as a set, and the pair carries the light preload as supplied.

Fitting notes

Mounting is an interference fit on the shaft and a close fit in the housing bore, both held to super-precision spindle limits. The pair goes onto the shaft in the orientation marked on the rings, with the scribe lines aligned; faces seat against square ground shoulders, and a runout error at the shoulder transfers directly into the raceway.

Interchange guidance

The 9500WI envelope is specific to the Fafnir series and has no ISO 7000-series counterpart at 45 × 80 × 18 mm, so a 7009 or a 7209 is a related size rather than an interchange. The 3MM9509WI is a 25° bearing in the same envelope, and the DUM and DUH variants differ in preload — also related sizes.