Fafnir3MM307WIDULSuper-Precision Angular Contact Ball Bearing 35x80x21 mm, 25 Degree Contact Angle, Light Preload, Phenolic Cage, 5 Pcs

Product Description

What this part is

A Fafnir 3MM307WI-DUL super-precision angular contact ball bearing, 35 mm bore by 80 mm outside diameter by 21 mm wide, with a phenolic cage. Five pieces are supplied. Fafnir is Timken’s super-precision line.

Decoding the designation

The 3MM prefix sets a 25° contact angle and the MM prefix carries P4S precision, equivalent to ABEC 7/9. The 307 size code gives a 35 mm bore on the ISO base number 7307. WI marks the super-precision angular contact family, CR the phenolic outer-land-riding cage, and DUL a universal duplex grind at light preload.

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15° of the same envelope, which suits spindles and screw drives that see substantial axial load alongside radial. The phenolic cage rides on the outer ring land and runs quieter and cooler than a steel cage at high speed, with a lower service temperature ceiling in exchange.

Quantity and configuration

Five pieces. Each is universally ground, so any two mount together as a back-to-back, face-to-face or tandem duplex set and come up to light preload when clamped without shims.

Fitting notes

Mounting is onto a clean straight journal against a square shoulder, with the marked ring faces oriented to the chosen arrangement. Phenolic cages absorb lubricant, so the bearings are run in gently after an oil change.

Interchange guidance

Same-spec equivalents at 25° and P4-class precision are the SKF 7307 ACD/P4A, the FAG B7307-E-T-P4S and the NSK 7307A5TRDULP4. A 7307 at a 15° or 40° angle, or in a steel cage, is a related size rather than an interchange.