Fafnir2MM9115WIDUHSuper-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, Heavy Preload

Product Description

What this part is

Fafnir 2MM9115WI-CR-DUH 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, sealed in the factory wrapping.

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 DUH a duplex arrangement at heavy preload.

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. Heavy preload gives the stiffest and most repeatable spindle of the three standard settings, holding position under cutting thrust with no lost motion, and costs running temperature and speed capability against a light or medium set. The 15° contact angle keeps the 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. This is a preloaded set rather than a clearance-fitted bearing: the heavy preload is built into the ground ring offsets. 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. Operating range is –30 to 100 °C on oil or grease.

Interchange guidance

Same-specification 15° heavy-preload duplex equivalents include the SKF 7015 CD/P4ADGC, FAG B7015-C-T-P4S-DUH and RHP 7015CTDUHP4. A 3MM9115WI of the same envelope is a 25° bearing and a related size rather than a substitution, and the DUL and DUM versions of this same bearing differ only in preload setting.