Fafnir3MM207WITBL-1/3SETSuper Precision Angular Contact Ball Bearing – Straight Bore, 35 mm ID, 72 mm OD, 17 mm Width, Open, 25° Contact Angle, Light Preload, ABEC 7, Machined Phenolic Cage

Product Description

What this part is

Fafnir 3MM207WITBL-1/3SET super-precision angular contact ball bearing, now supplied under the Timken brand. Bore: 35 mm. Outside Diameter: 72 mm. Width: 17 mm. Contact Angle: 25°. Precision Class: ABEC 7 / P4. Series: WI super-precision machine-tool spindle series. Base Number: 7207. Cage: machined one-piece phenolic textile laminate. Closure: Open. Preload: Light. Rolling Elements: Ball. Number of Rows: 1. Bore Type: Straight. Mounting Arrangement: Universal. Design Units: Metric. Country of Origin: United States.

Decoding the designation

3MM: 25° nominal contact angle in the Fafnir and Timken super-precision scheme. 207: ISO 72-series boundary dimensions, 35 x 72 x 17 mm, ISO base number 7207. WI: super-precision machine-tool spindle series. T: machined one-piece phenolic textile-laminate cage. L: light preload class. -1/3SET: carton marking for one piece of a three-bearing set. Searchable forms of the designation: 3MM207WITBL-1/3SET, 3MM207WITBL, 3MM-207-WI-TBL, 3MM 207 WI TBL, 3MM207WI, 3MM-207-WI.

Published ratings

Basic Dynamic Load Rating (Cr): 32 kN. Basic Static Load Rating (C0r): 16.2 kN. Limiting Speed: 17,400 rpm. Maximum Operating Temperature: 120 °C. Minimum Operating Temperature: -30 °C. Material: bearing steel. Item Weight: 1.28 lbs. Harmonization Code: 8482.10.50.68.

What these specs mean in practice

Contact angle is the decisive number on this bearing. A 25° angle carries substantially more thrust load than a 15° bearing of the same envelope and accepts axial preload more readily, which is why 25° bearings dominate drilling, boring and heavily thrust-loaded spindle positions. The steeper angle moves the ball load path further off the radial plane and raises centrifugal cage and ball loading, so the speed ceiling and radial stiffness sit below those of a 15° bearing in the same bore.

Why a phenolic cage matters

Phenolic cotton-reinforced textile laminate is light, so cage centrifugal stress stays low at high DN values. It is mildly porous, so it holds oil and behaves forgivingly through a marginal-lubrication event. It also sets the temperature ceiling, which for this cage material is approximately 120 °C. Cleaning is compatible with conventional petroleum-based solvents.

Quantity and configuration

Unit Quantity: 1 Pc. One bearing per unit. The -1/3SET carton marking identifies this piece as one of an original matched three-bearing set, sold individually.

Fitting notes

Shaft and housing geometry is held to the precision-class tolerances stated on the spindle drawing. Mounting is by even axial pressure applied to the ring being fitted, with the load path kept clear of the balls. Assembly cleanliness is held to super-precision standards. Preloaded angular contact bearings are directional in service, so ring face orientation is recorded before disassembly of an existing set.

Interchange guidance

Fafnir became part of Timken, so Fafnir to Timken is the obsolescence trail for a current replacement. Closest angle match: SKF 7207 ACD at 25°. Same-envelope alternatives at other contact angles: SKF 7207 CD at 15°, NSK 7207A5 at 30°, NSK 7207C at 15°, NSK 7207A, FAG B7207-E, and the Fafnir 15° sibling 2MM207WI. Interchange is governed by contact angle, precision class, cage material and preload class as well as by the 35 x 72 x 17 mm envelope.