Fafnir3MM9114WIDULSuper Precision Angular Contact Ball Bearing, Duplex Pair, 70 x 110 x 20 mm, 25 Degree Contact Angle, Light Preload, Phenolic Outer-Land-Riding Cage, ABEC 7/9

Product Description

What this part is

Fafnir 3MM9114WI-DUL, a Timken super precision angular contact ball bearing for machine tool spindles, supplied as a universally ground duplex pair at light preload. Brand: Fafnir (Timken). Bore: 70 mm. Outside Diameter: 110 mm. Overall Width: 20 mm per bearing. Total Width: 40 mm as an assembled pair. Contact Angle: 25°. Preload: Light. Precision Class: ISO P4S, ABEC 7/9. Arrangement: DU, duplex universally ground. Number Of Rows: 2, one row per bearing. Cage Material: Phenolic, Timken cage designation MBR. Cage Type: CR, outer-land-riding. Rolling Elements: Steel balls. Bearing Material: Bearing steel. Closure Type: Open. Bore Type: Straight. Lubricant: Oil or grease. Series: 9100WI, 3MM super precision metric. Base Number: 3MM9114WI. Design Units: Metric. Item Weight: 2.60 lb. Harmonization Code: 8482.10.50. Timken’s published world part number is 7014E-T-P4S-DUL.

Published ratings and mounting data

Dynamic Radial Load Rating C1 at 1 million revolutions: 10,700 lbf, 47,600 N. C1 ISO Dynamic Radial Rating per row: 9,730 lbf, 43,300 N. Static Radial Load Rating C0: 8,730 lbf, 38,800 N. Limiting Speed: 11,600 rpm on grease, 21,000 rpm on oil. Maximum Shaft Fillet Radius: 1 mm. Shaft Backing Shoulder Diameter: 77.7 mm. Housing Backing Shoulder Diameter: 102.4 mm. Outer Ring To-Clear Radius: 1 mm. Operating Temperature Range: -30 °C to 120 °C. These are Timken’s published catalogue figures for 3MM9114WI DUL and belong to the 25° 3MM variant; the 15° 2MM9114WI carries different ratings.

Decoding the designation

3MM: Fafnir and Timken super precision metric series, 25° contact angle. 9114: 9100WI dimension series, 70 mm bore. WI: the standard Fafnir super precision spindle angular contact ball bearing series. CR: phenolic outer-land-riding cage, Timken designation MBR. DU: duplex universally ground, a matched pair that mounts in any orientation without shims. L: light preload. The MM prefix carries ISO P4S, ABEC 7/9. In the world numbering scheme the letter after the series number is the contact angle, and 25° takes an E, which is why Timken publishes 7014E-T-P4S-DUL. Searchable variants: 3MM9114WI-DUL, 3MM9114WIDUL, 3MM-9114-WI-CR-DUL, 3MM9114WICRDUL, 3MM 9114 WI CR DUL, 3MM9114WI, 7014E-T-P4S-DUL, 7014E, 7014, 7014A.

What these specs mean in practice

The 25° contact angle is the rigidity-biased choice. Against a 15° bearing in the same envelope, the steeper angle carries substantially more thrust and deflects less axially under load, which is what a spindle taking real cutting thrust needs. It costs speed: a steeper angle raises ball spin, gyroscopic moment and cage loading, so limiting speed and the heat generated at a given rpm are both worse than the 15° part. 25° buys stiffness; 15° buys rpm.

Light preload pulls the other way, and the combination is deliberate. Pairing a stiff 25° contact angle with the lightest preload class gives the thrust capacity and axial rigidity of the steep angle while keeping friction, heat generation and grease consumption to a minimum, which suits a spindle that has to be both reasonably stiff and reasonably fast. Preload class is part of the spindle design; a DUM or DUH set changes both the stiffness and the thermal behaviour.

The phenolic outer-land-riding cage is what keeps a 25° bearing viable at speed. Phenolic is light and mildly self-lubricating, so it generates far less heat than a steel cage, and riding on the outer ring land lets centrifugal force stabilise the cage rather than load it. Phenolic is attacked by some solvents.

Quantity and configuration

Unit Quantity: 1 matched duplex pair, two bearings. DUL designates a duplex pair, so the sale unit is two bearings ground and matched to each other as a set, supplied and priced as one set.

Fitting notes

Universally ground rings allow the pair to be mounted back-to-back, face-to-face or in tandem, assembled in the orientation the machine calls for and clamped square. Preload develops from clamping the ground faces solidly together, so a burr, a dirt film or an out-of-square abutment on the shaft or housing shoulder translates directly into wrong preload and lost running accuracy, and a light-preload set has little margin. The 77.7 mm shaft and 102.4 mm housing backing shoulder diameters apply, with 1 mm fillet clearance. Handling is by the outer ring, in the original packaging until assembly, with a progressive run-in before full speed.

Interchange guidance

Timken’s published world equivalent is 7014E-T-P4S-DUL, where E denotes the 25° contact angle, T the phenolic cage and P4S the precision grade. A matching substitute carries the contact angle, precision grade, preload class, cage material and duplex arrangement together alongside the 70 x 110 x 20 mm envelope. The NSK 7014A5TYNDULP4 is the same 25° universally ground light-preload duplex pair with a polyamide cage in place of phenolic. The SKF 7014 ACD/P4ADGA is a 25° universally matchable pair at extra light preload rather than light. The Fafnir 3MM9114WI-DUM is the medium-preload set, and the 2MM9114WI or 7014C is the 15° version. Clearance-graded or steel-caged 7014 bearings share the envelope only. The 7015 series is a 75 x 115 x 20 mm bearing, a different size. Fafnir super precision bearings are supplied under the Timken brand, so Fafnir and Timken designations of this form are the same product line.