Fafnir2MM9104WIDUHAngular Contact Ball Bearing – 20 mm ID, 42 mm OD, 12 mm Width, Open, 15° Contact Angle, Heavy Preload, P4S (ABEC 7/9), Matched Duplex Pair

Product Description

What this part is

Fafnir 2MM9104WI-CR-DUH super-precision angular contact ball bearing, supplied as a matched duplex universal pair. Bore: 20 mm. Outside Diameter: 42 mm. Overall Width: 12 mm. Contact Angle: 15°. Series: 9100WI, the Fafnir extra-light spindle series. Bearing Type: Angular contact ball bearing. Number Of Rows: 1 per bearing. Rolling Elements: Balls. Bore Type: Straight. Closure Type: Open. Material: Bearing steel.

Decoding the designation

Precision Class: P4S, equivalent to ABEC 7/9 — the Fafnir MM super-precision grade. Cage Material: Phenolic. Cage Type: Machined, outer-ring land-riding. Preload: Heavy. Mounting Arrangement: Duplex universal, DU. Internal Clearance: N/A, the pair is preload-set. Searchable variants of the number: 2MM9104WIDUH, 2MM-9104-WI-CR-DUH, 2MM9104WICRDUH, 2MM 9104 WI DUH.

What these specs mean in practice

Dynamic Load Rating: 11.6 kN (2,600 lbf). Static Load Rating: 6 kN (1,350 lbf). Limiting Speed: 37,100 rpm. Max Temperature: 120 °C. Min Temperature: -30 °C. Item Weight: 0.32 lbs. A 15° contact angle favours speed and radial rigidity over axial capacity, which is what machine-tool spindles ask for. Heavy preload raises stiffness and holds shaft position under changing load. The phenolic cage is light and runs quietly at high speed.

Quantity and configuration

Unit Quantity: 2 Pcs. A matched duplex universal pair. The faces are universally flush-ground, so the two bearings mount back-to-back, face-to-face or in tandem and reach the specified heavy preload when clamped. Country of Origin: United States.

Fitting notes

Clamp the rings against square, flat abutments so the ground faces seat evenly and the preload comes up as specified. The outer-ring land-riding phenolic cage suits oil, oil-mist and grease lubrication at high speed. Harmonization Code: 8482.10.50.

Interchange guidance

Cross-Reference: SKF 7004 CD/P4A DGC — a 15° heavy-preload universal pair on the same 20 x 42 x 12 mm envelope. ISO equivalent: 7004 C. Bearings of the same envelope built at a 25° contact angle are a related size rather than a substitution, because the thrust and speed characteristics differ.