Fafnir2MM216WISuper Precision Angular Contact Ball Bearing 80x140x26 mm, 15° Contact Angle, Phenolic Cage, ABEC 7, Universally Ground

Product Description

What this part is

A Fafnir 2MM216WI super-precision angular contact ball bearing, 80 mm bore x 140 mm outside diameter x 26 mm wide — the 7216 envelope. The outer ring is counterbored on one side so the full ball complement can be loaded and so the bearing develops a contact angle. It takes radial load plus thrust in one direction, and the high shoulder must face the thrust.

Decoding the designation

2 – the numeric prefix names the contact angle in Timken/Fafnir super-precision numbering: 2MM = 15°, 3MM = 25°.
MM – Fafnir’s super-precision tolerance grade, ABEC 7. Note that a single M would be ABEC 3, so the doubled letter is doing real work here.
216 – 200 series, bore code 16, so 80 mm bore.
WI – maximum-capacity (filling-slot) type with the outer ring counterbored, which is what makes it angular contact rather than deep groove.
CR – composition retainer: a phenolic laminated-fabric cage, stamped on the carton rather than the ring.

What these specs mean in practice

A 15° contact angle is the high-speed end of the range. The shallow angle means the ball load path is closer to radial, so centrifugal ball loading and heat generation stay lower and the bearing tolerates a higher DN value than a 25° or 40° equivalent. What you give up is thrust capacity and axial stiffness — a 15° bearing is the wrong choice for a thrust-dominant spindle. That is the trade, and it is why grinding spindles and high-speed milling heads run 15° while heavy boring and drilling positions run 25° or steeper.

ABEC 7 controls bore, outside diameter, width and, most importantly, radial and axial runout, so the ring can be fitted in any rotational orientation without hunting for a high spot. The phenolic cage completes the high-speed package: light, so cage inertia is low; self-lubricating, so it survives marginal lubrication; and soft enough that a ball skid polishes the pocket rather than galling it. Its limits are sustained heat much above roughly 120 °C and attack by some synthetic lubricants and cleaning solvents.

Published dimensions

Bore (d): 80 mm
Outside diameter (D): 140 mm
Width (B): 26 mm
Contact angle: 15°
Rows: 1
Cage: phenolic / laminated fabric composition (CR)
Precision: ABEC 7
Closure: open, no seals or shields
Outer ring: counterbored one side

Quantity and configuration

Sold as one bearing. This is a single, not a matched duplex set — there is no supplied preload. The WI series is universally ground, however, so two of these can be clamped face-to-face, back-to-back or in tandem and will develop a repeatable preload; where a drawing calls for a factory-matched pair with a specified preload class, order a DUL, DUM or DUH set instead.

Fitting notes

Orient the counterbored (low shoulder) side away from the thrust load — fitted backwards the balls climb the raceway shoulder and the bearing fails quickly. Press or induction-heat onto the shaft against the inner ring only; never hammer an ABEC 7 bearing and never drive force through a phenolic cage. Grease sparingly, roughly a quarter to a third fill, or use the oil-air system the spindle was designed around. A single angular contact locates the shaft in one direction only, so it needs an opposing bearing in the arrangement.

Interchange guidance

Fafnir is now sold by Timken, so Timken 2MM216WI and Fafnir 2MM216WI are the same part. Same-envelope 80 x 140 x 26 mm super-precision 15° equivalents: NSK 7216CTYNSULP4 (C is NSK’s 15° code — a direct match), SKF 7216 CD/P4A (SKF CD is 15°), NTN 7216CT1P4 (NTN C is 15°), RHP 7216CTP4. Carried as dimensionally-correct cross-references with the difference named: SKF 7216 ACD/P4A and NSK 7216A5TYNP4 are the same envelope at 25°, and FAG 7216-B-TVP-P4 is the same envelope at 40° — all three fit the same bore and housing but change the thrust and speed behaviour, so match the angle your spindle was built around. The 7216 C D P4A reading that has travelled with this record is a mixed-nomenclature form and is kept as a search term only.