Fafnir2MM215WISuper Precision Angular Contact Ball Bearing, 75 x 130 x 25 mm, 15 Degree Contact Angle, Phenolic Outer-Land-Riding Cage, Open, ABEC 7/9

Product Description

What this part is

Fafnir 2MM215WI, a Timken super precision angular contact ball bearing for machine tool spindles. Brand: Fafnir (Timken). Bore: 75 mm. Outside Diameter: 130 mm. Overall Width: 25 mm. Contact Angle: 15°. Precision Class: ISO P4S, ABEC 7/9. Cage Material: Phenolic, Timken cage designation MBR. Cage Type: CR, outer-land-riding. Closure Type: Open, no shields and no seals. Number Of Rows: 1. Rolling Elements: Steel balls. Bearing Material: Bearing steel. Bore Type: Straight. Lubricant: Oil. Series: 200WI, 2MM super precision metric. Base Number: 2MM215WI. Design Units: Metric. Item Weight: 2.65 lb. Harmonization Code: 8482.10.50.28. This is a spindle bearing: the tolerance grade, the phenolic cage and the ground faces exist to hold a shaft concentric at high rpm under a combined radial and axial load.

Published ratings and mounting data

Dynamic Radial Load Rating C1 at 1 million revolutions: 19,800 lbf, 87,900 N. C1 ISO Dynamic Radial Rating per row: 18,000 lbf, 79,900 N. Static Radial Load Rating C0: 14,600 lbf, 64,900 N. Limiting Speed: 10,800 rpm on grease, 21,600 rpm on oil. Maximum Shaft Fillet Radius: 1.5 mm. Shaft Backing Shoulder Diameter: 85.2 mm. Housing Backing Shoulder Diameter: 120.8 mm. Outer Ring To-Clear Radius: 1.5 mm. Operating Temperature Range: -30 °C to 121 °C. These are Timken’s published catalogue figures for 2MM215WI and hold across the preload variants of this bearing. They apply to the 15° 2MM variant; a 25° 3MM215WI carries different numbers.

Decoding the designation

2MM: Fafnir and Timken super precision metric series, 15° contact angle. 215: 200WI dimension series, 75 mm bore. WI: the standard Fafnir super precision spindle angular contact ball bearing series. CR: phenolic outer-land-riding cage, Timken designation MBR. The MM prefix carries ISO P4S, ABEC 7/9. Searchable variants: 2MM215WI, 2MM215WICR, 2MM-215-WI-CR, 2MM 215 WI CR, 2MM215W1, 7215C-T-P4S, 7215C, 7215.

What these specs mean in practice

The 15° contact angle is the speed-biased choice within the super precision range. 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 tolerates higher rpm than a 25° bearing in the same envelope. It gives up axial stiffness and thrust capacity: under the same thrust a 15° set deflects more than a 25° set. 15° suits designs where speed and thermal headroom decide; 25° suits rigidity under heavy cutting thrust.

The phenolic outer-land-riding cage is what makes those speeds usable. Phenolic is light and mildly self-lubricating, generating far less heat than a steel cage, and riding on the outer ring land means centrifugal force stabilises the cage rather than loading it. The cage depends on the oil film, and phenolic is attacked by some solvents.

Open construction is deliberate on a spindle bearing. There is no seal or shield to add drag or trap heat, which is a requirement for oil-mist, oil-air or circulating-oil lubrication. Contamination control is handled by the spindle’s own sealing arrangement.

Fitting notes

The 85.2 mm shaft and 120.8 mm housing backing shoulder diameters apply, with 1.5 mm fillet clearance, so the bearing corners clear the shoulder radius and the rings seat square. Where this bearing is paired with another to form a set, both carry the same designation from the same manufacturer and the ground faces clamp solidly and squarely; a burr, a dirt film or an out-of-square abutment translates directly into wrong preload and lost running accuracy. 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 part number form is 7215C-T-P4S, where C denotes the 15° contact angle, T the phenolic cage and P4S the precision grade, with the arrangement and preload suffix appended after that. The MM prefix carries P4S. A matching substitute carries the 15° contact angle, ISO P4S precision, a phenolic cage and open construction alongside the 75 x 130 x 25 mm envelope. Same-envelope related sizes: SKF 7215 CD/P4A, NSK 7215CTYNP4, FAG B7215-C-T-P4S, and the 25° 3MM215WI or 7215E. Fafnir super precision bearings are supplied under the Timken brand, so Fafnir and Timken designations of this form are the same product line.