Fafnir2MM9109WIDULHigh-Speed Super Precision Angular Contact Ball Bearing, Duplex Pair, 45 x 75 x 16 mm, 15 Degree Contact Angle, Light Preload, Phenolic Outer-Land-Riding Cage, 21,480 rpm Grease Limit, ABEC 7/9

Product Description

What this part is

Fafnir 2MMV99109WN-DUL, a Timken high-speed super precision angular contact ball bearing for machine tool spindles, supplied as a universally ground duplex pair at light preload. Brand: Fafnir (Timken). Bore: 45 mm. Outside Diameter: 75 mm. Overall Width: 16 mm per bearing. Contact Angle: 15°. 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. Closure Type: Open. Series: 2MMV99, the WN high-speed super precision metric execution. Base Number: 2MMV99109WN. Design Units: Metric. Timken’s published world part number is C7009C-T-P4S-DUL.

Published ratings and mounting data

Dynamic Radial Load Rating C1 at 1 million revolutions: 6,080 lbf, 27,000 N. C1 ISO Dynamic Radial Rating per row: 5,530 lbf, 24,500 N. Static Radial Load Rating C0: 3,850 lbf, 17,180 N. Limiting Speed: 21,480 rpm on grease, 42,960 rpm on oil. Maximum Shaft Fillet Radius: 1 mm. Shaft Backing Shoulder Diameter: 51.3 mm. Housing Backing Shoulder Diameter: 69.3 mm. Outer Ring To-Clear Radius: 1 mm. Ball Type: steel. These are Timken’s published catalogue figures for 2MMV99109WN DUL and are specific to the WN high-speed execution.

Decoding the designation

2MM: Fafnir and Timken super precision metric series, 15° contact angle. V99: the high-speed design execution prefix, reflected by the leading C in Timken’s world part number C7009C-T-P4S-DUL. 109: 45 mm bore in the 9100 dimension series. WN: the design and cage execution code. 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. Searchable variants: 2MMV99109WN-DUL, 2MMV99109WNDUL, 2MM-V-9-9109-WN-DUL, 2MMV99109WNCRDUL, 2MM V99 109 WN DUL, 2MMV99109WN, C7009C-T-P4S-DUL, C7009C, 7009.

WN and WI are different executions

2MMV99109WN and 2MM9109WI share the 45 x 75 x 16 mm envelope, the 15° contact angle and the ISO P4S grade, and Timken publishes them as different bearings with different numbers. The WN high-speed execution is rated to 21,480 rpm on grease and 42,960 rpm on oil, with a 3,850 lbf static rating. The standard WI bearing in the identical envelope is rated to 17,900 rpm on grease and 35,800 rpm on oil, with a 4,330 lbf static rating. WN buys roughly twenty percent more speed envelope; WI buys static capacity. The execution code decides which.

What these specs mean in practice

The 15° contact angle is the speed-biased choice. A shallower angle keeps the ball load line closer to radial, which reduces ball spin, gyroscopic moment and cage loading, so the bearing runs cooler and faster than a 25° bearing in the same envelope, at the cost of axial stiffness and thrust capacity. On a high-speed execution the shallow angle and the speed rating are the same design decision.

Light preload continues in that direction: the lowest friction, the least heat and the longest grease life of the three preload classes, at the cost of axial stiffness. It is the class that matches a 21,480 rpm grease limit.

The phenolic outer-land-riding cage is what makes the speed rating achievable. Phenolic is light and mildly self-lubricating, so it generates far less heat than a steel cage, and riding on the outer ring land means centrifugal force stabilises the cage rather than loading it, which is the failure mode that limits speed on an inner-land-riding or steel cage. Phenolic is attacked by some solvents and depends on the oil film.

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 translates directly into wrong preload and lost accuracy, and at 21,000 rpm a corrupted preload becomes a thermal problem quickly. The 51.3 mm shaft and 69.3 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 staged run-in before full speed.

Interchange guidance

Timken’s published world equivalent is C7009C-T-P4S-DUL. A matching substitute carries the WN high-speed execution alongside the 15° contact angle, ISO P4S grade, phenolic cage, light preload and duplex arrangement. The standard 2MM9109WI and 7009C-T-P4S-DUL share the 45 x 75 x 16 mm envelope and the contact angle at a lower speed rating and a higher static rating, so they are a related size. Fafnir super precision bearings are supplied under the Timken brand, so Fafnir and Timken designations of this form are the same product line.