Fafnir2MM9124WIDUHSuper-Precision Angular Contact Bearing Matched Pair 120x180x28 mm 15° Heavy Preload Phenolic Cage ABEC 7/9

Product Description

What this part is

Fafnir 2MM9124WI-DUH matched duplex pair of super-precision single-row angular contact ball bearings, universally ground. Bore: 120 mm (4.724 in). Outside Diameter: 180 mm (7.087 in). Bearing Width: 28 mm (1.102 in) per bearing. Total Width: 56 mm (2.205 in) as a pair. Series: Fafnir 9100WI spindle series, ISO 7024 envelope. Timken World Part Number: 7024C-T-P4S-DUH. Rolling Elements: steel balls. Cage Type: CR — Phenolic Outer Land Riding Cage. Cage Material: phenolic textile laminate. Closure Type: open. Number of Rows: 1 per bearing.

Decoding the designation

Contact Angle: 15°. Precision Rating: ISO P4S (ABEC 7/9). Preload: Heavy. 2MM is the Fafnir super-precision prefix at the 15° angle, and the MM prefix carries the P4S build. The Fafnir 91xx block maps to the ISO 70xx dimension series, so 9124 is the 7024 envelope at 120 x 180 x 28 mm. WI identifies the super-precision angular contact spindle family with a low shoulder on both rings. CR is the phenolic cage riding on the outer ring land. DUH is a duplex pair, universally ground, at heavy preload. Searchable forms of the number include 2MM9124WI-DUH, 2MM9124WIDUH, 2MM9124WICRDUH, 2MM-9124-WI-CR-DUH, 2MM 9124 WI CR DUH and 7024-C.

What these specs mean in practice

Dynamic Load Rating (C1, Timken 1M revs, set): 111.2 kN / 25,000 lbf. Dynamic Load Rating (C1 ISO, per row): 101 kN / 22,700 lbf. Static Load Rating (C0): 108.5 kN / 24,400 lbf. Limiting Speed, grease: 6,900 rpm. Limiting Speed, oil: 13,800 rpm. A 15° contact angle carries less thrust and runs faster than a 25° bearing in the same envelope, and it gives a stiffer radial response for a given preload. Heavy preload is the stiffest of the three grades, holding spindle position under cut with the least deflection for more heat generated at speed. The phenolic outer-land-riding cage, at roughly a fifth the density of brass, loads itself far less under centrifugal force, and the laminate holds a small oil reserve; outer-land riding keeps the cage guided by the outer ring so it stays concentric at speed.

Mounting dimensions

Shaft Backing Shoulder Diameter: 132.5 mm (5.220 in). Housing Backing Shoulder Diameter: 168.3 mm (6.630 in). Maximum Shaft Fillet Radius: 2 mm (0.079 in). Outer Ring To Clear Radius: 2 mm (0.079 in). Bore Type: straight.

Quantity and configuration

Unit Quantity: 2 Pcs, one matched duplex pair. Rows per set: duplex. Each bearing carries thrust in one direction. Universal grinding lets the pair clamp back-to-back for two-direction thrust and maximum moment stiffness, face-to-face for a narrower effective spread, or in tandem to double one-direction thrust, each arrangement developing the specified heavy preload when clamped solid.

Interchange guidance

Same-envelope 15° super-precision equivalents at heavy preload include RHP 7024CTDUHP4, FAG B7024C.T.P4S.UH, SKF 7024 CD/P4ADGC and NSK 7024CTRDUHP4. Timken’s own world part number for this set is 7024C-T-P4S-DUH, and C denotes the 15° angle in that scheme. The 25° 3MM9124WI shares the envelope at a different contact angle and is a related size.