Fafnir3MM9112WIDUHSuper-Precision Angular Contact Ball Bearing Pair – 60 mm ID, 95 mm OD, 18 mm Width Each, 36 mm Pair, 25° Contact Angle, Phenolic Cage, Heavy Preload

Product Description

What this part is

A Timken Fafnir 3MM9112WI-CR-DUH super-precision angular contact ball bearing, supplied as a matched pair. Bore 60 mm, outside diameter 95 mm, width 18 mm per bearing, 36 mm across the assembled pair. Open on both faces, with a fabric-base phenolic cage riding on the outer ring lands.

Decoding the designation

The leading 3MM sets a 25° contact angle. The MM prefix denotes Fafnir super-precision execution to P4S, equivalent to ABEC 7/9. The 9100 series number decodes to the ISO 70 light series, so 9112 is the ISO 7012 envelope at 60 x 95 x 18 mm. CR is the phenolic cage. DUH is a universally matchable duplex pair set to heavy preload.

What these specs mean in practice

A 25° contact angle carries more thrust and tolerates less speed than a 15° bearing of the same envelope. Heavy preload raises axial and radial stiffness and improves running accuracy under load, at the cost of higher friction, more heat and a lower practical speed than the light and medium grades. Because the pair is preload-set rather than clearance-set, internal clearance is not applicable to it.

Quantity and configuration

Two bearings, sold as a matched set. Universally matchable duplex construction allows the pair to be mounted back-to-back, face-to-face or in tandem, the ground faces producing the specified heavy preload when clamped.

Fitting notes

The rings are ground as a set and stay together. Clamping is applied evenly against the ground faces so the designed preload is established without ring distortion. Heavy preload runs warmer, so lubricant selection and quantity follow the higher heat generation.

Interchange guidance

Same-specification equivalents are SKF 7012 ACD/P4A DGC and NSK 7012A5TYNDUHP4. A 7012 CD or C variant shares the 60 x 95 x 18 mm envelope at a 15° contact angle, and a DUL or DUM set carries a lighter preload; both are related sizes rather than interchanges.