Fafnir2MM9109WISuper-Precision Angular Contact Ball Bearing – 45 mm ID, 75 mm OD, 16 mm Width, 15 Degree, Phenolic Cage, P4S

Product Description

What this part is

Timken Fafnir 2MM9109WI super-precision angular contact ball bearing, 45 mm bore, 75 mm outside diameter, 16 mm width. Single row, open on both faces, steel balls, phenolic outer-land-riding cage, ISO P4S precision.

Decoding the designation

In the Fafnir spindle-bearing scheme the 2MM prefix sets a 15° contact angle, and the MM itself denotes the P4S precision grade, equivalent to ABEC 7/9. The 9100WI series maps to the ISO 70 light series, so 9109WI is the ISO 7009 envelope at 45 x 75 x 16 mm. WI denotes the spindle bearing execution and CR the phenolic outer-land-riding cage.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness; a 25° bearing of the same envelope carries more thrust and runs slower. The outer-land-riding phenolic cage is guided on the outer ring land, which keeps the cage stable at speed and is what supports the 35,800 rpm oil-lubricated limit against 17,900 rpm on grease. Basic dynamic radial rating is 6,080 lbf and basic static radial rating 4,330 lbf.

Quantity and configuration

One bearing, supplied in the bare execution.

Mounting dimensions

Inner ring backing diameter 2.020 in and outer ring backing diameter 2.730 in. Maximum shaft and housing fillet radius to clear the bearing is 0.039 in on both rings. Ball diameter is 0.34375 in.

Fitting notes

P4S rings are ground to ISO class 4 running accuracy, so shaft and housing seats need matching form and roundness for the tolerance to be realised. Oil lubrication suits the phenolic cage and the upper speed range.

Interchange guidance

Same-envelope, same-angle super-precision equivalents are the SKF 7009 CD/P4A, the NSK 7009CTRP4 and the FAG B7009-C-T-P4S. The Timken 2MM9109WI DUL and DUM are the same bearing supplied as preloaded matched pairs.