Fafnir2MM9115WIDULSuper-Precision Angular Contact Ball Bearing Duplex Set of 2 – 75 mm Straight Bore, 115 mm OD, 20 mm Width Each, 15° Contact Angle, Open, Phenolic Machined Cage, Light Preload

Product Description

What this part is

Fafnir 2MM9115WI-CR-DUL-FS637 super-precision angular contact ball bearings, 75 mm bore, 115 mm outside diameter, 20 mm width per bearing. Single row each, open on both faces, machined phenolic outer-land-riding cage. ISO base number 7015. Two pieces, supplied as a duplex set.

Decoding the designation

2MM sets a 15° contact angle in the Fafnir WI super-precision scheme, and the MM prefix carries P4S precision — ABEC 7 dimensional tolerances, which is the ABEC7 marked on the carton, with ABEC 9 running accuracy. The leading 9 of 9115 places the bearing in the ISO 70 light dimension series, so the ISO base number is 7015. WI is the ground spindle execution, CR the phenolic outer-land-riding cage, and DUL a duplex arrangement at light preload. FS637 is a Timken special-features code carried on the carton.

What these specs mean in practice

Basic dynamic capacity is 51.6 kN and static capacity 43.5 kN, with a limiting speed of 11,000 rpm. Light preload is the fastest and coolest-running of the three standard settings: it gives the highest speed capability and the lowest power loss, and trades away some axial stiffness against a medium or heavy set. The 15° contact angle reinforces that bias towards speed and radial stiffness rather than thrust.

Quantity and configuration

Two bearings, 20 mm wide each, 40 mm total mounted width as a duplex stack. Universally ground faces, so the pair mounts back-to-back, face-to-face or in tandem.

Fitting notes

Straight bore on an interference fit to the spindle journal, outer rings clamped square in the housing bore. The ground faces are stacked with the marked faces oriented together per the chosen arrangement, and the light preload is developed by the ground offsets. Operating range is –30 to 120 °C on oil or grease.

Interchange guidance

Same-specification 15° light-preload duplex equivalents include the SKF 7015 CD/P4ADGA, FAG B7015-C-T-P4S-DUL and NSK 7015CTYNDULP4. A 3MM9115WI of the same envelope is a 25° bearing and a related size rather than a substitution, and a DUM or DUH version of this same bearing differs only in preload setting.