Timken2MM9116WI-SULSuper Precision Angular Contact Ball Bearing 80 x 125 x 22 mm, 15° Contact Angle, ABEC 7/9, Universally Flush Ground Single

Product Description

What this part is

A single Fafnir (now Timken) 2MM9116WI super precision angular contact ball bearing, 80 mm bore × 125 mm outside diameter × 22 mm wide. It belongs to the 9100 extra-light series — ISO 10 series, the 7016 envelope — and is ground to ABEC 7/9 tolerances. This is a machine tool spindle bearing: not a general-purpose bearing, and not an automotive part.

Decoding the designation

2 — Timken code for a 15° contact angle. ISO writes the same angle as C.
MM — super precision, between ABEC 7 (ISO P4) and ABEC 9 (ISO P2). Timken’s MV grade is plain ABEC 7 / P4; MM is the higher of the two.
9116 — 9100 extra-light series, bore code 16 (16 × 5 = 80 mm).
WI — angular contact construction with a low shoulder on the outer ring only.
SUL — universally flush ground single bearing at light preload. SU is a single, DU a duplex pair, TU a triplex set; X, L, M and H are extra-light, light, medium and heavy preload.

Correcting the source data

The source listing gave the ISO world part number as 7016C-T-SUL-P4. The precision code was wrong. Timken’s MM prefix maps to P4S (ABEC 7/9), not to P4 (ABEC 7) — a P4 bearing in this family would be numbered 2MV9116WI. The corrected world part number is 7016C-T-P4S-SUL. Both forms are carried as cross-references so either search reaches this page.

What the carton and ring markings actually say

The original Fafnir “Super Precision” carton label reads simply 2MM9116 WI, with no preload or matching suffix at all. The ring etch reads 2MM9116WI, then a short character group that is not fully legible through the sealed factory wrapper, then a C2 manufacturing code and LOT # 688xx. The illegible group contains a D, which leaves open the possibility that this ring came from a duplex-matched set rather than being an SUL single — and a Fafnir “WI Series” instruction sheet for duplex universal pairs is packed in the box. One bearing is physically present. Because the preload class cannot be read with certainty, no preload figure is published on this page. Ask before buying if a specific preload class is critical to your build.

What these specs mean in practice

15° is the low-angle option in this family. It gives the highest speed capability and the lowest axial stiffness of the standard angles. The 25° alternative (Timken 3MM, ISO E) gives up roughly a tenth of the speed rating in exchange for substantially more thrust capacity and axial rigidity. Choose 15° when the spindle is speed-limited and predominantly radially loaded; choose 25° when heavy one-direction thrust or cutting load dominates. Universal flush grinding is the other half of the value: two or more of these stack directly into a DB, DF or DT set with the ground faces butted, no spacers and no measured shims, and the preload comes out at the designed figure. ABEC 7/9 is what buys the running accuracy — sub-micron radial and axial runout, which is what actually holds a bored diameter or a ground finish to tolerance.

Published ratings and mounting data

From the Timken Fafnir Super Precision Bearings for Machine Tool Applications catalogue (order 5918), 15° steel-ball columns:

Basic dynamic radial load rating C — 64,900 N (14,600 lbf)
Basic static radial load rating C0 — 55,200 N (12,400 lbf)
Speed rating (Ng) — 10,300 rpm, for a single grease-lubricated spring-preloaded bearing
Ball complement — 20 steel balls, 13.5 mm (17/32 in) diameter
Bearing weight — 0.859 kg (1.89 lb)
Maximum shaft fillet radius — 1.0 mm (0.039 in)
Suggested shaft shoulder diameter — 89.3 / 88.5 mm (3.52 / 3.49 in)
Suggested housing shoulder diameter — 116.5 / 115.7 mm (4.59 / 4.56 in)
Grease fill — 3.85 g (10 %) to 5.80 g (15 %) at high speed; 8.60 g (25 %) to 13.80 g (40 %) at low to moderate speed

Published duplex data for this size, back-to-back, for reference: DUL 310 N preload, 8,200 rpm grease / 13,900 rpm oil; DUM 670 N, 6,200 / 10,500 rpm; DUH 1,560 N, 4,100 / 7,000 rpm. Axial stiffness runs 92.87 N/µm at light preload to 189.59 N/µm at heavy.

Two specs are deliberately left blank. Timken publishes preload values only for duplex sets, never for SU singles. And cage material is not stated: phenolic (CR) is the standard for the WI family, but this part number carries no CR callout and the cage cannot be seen clearly through the sealed wrapper, so it is not claimed.

Quantity and configuration

One bearing. Universally ground super precision bearings are usually bought in pairs or sets, so it is worth being blunt: this listing is one piece, not a matched pair and not a set. If your spindle needs two, this is half the job.

Fitting notes

The WI construction puts a low shoulder on one side of the outer ring, so the bearing has a defined thrust direction and the marked face must face the load. Do not unwrap it until you are ready to mount, and mount it clean — a knock on a ground face or a trace of grit destroys exactly the tolerance you are paying for. The phenolic cage standard to this family is rated to about 93 °C (200 °F), the practical temperature ceiling for a grease-packed WI spindle bearing. Respect the published shoulder diameters and the 1.0 mm maximum fillet radius; oversized fillets and undersized shoulders are the usual reason a precision bearing will not seat square.

Interchange guidance

The 80 × 125 × 22 mm, 15° envelope is ISO 7016C. Same-envelope super precision bearings from other makers — NSK 7016CTYNSULP4, FAG B7016C.T.P4S, SKF 7016 CD/P4A, NTN 7016CT1DB/GNP4 — are dimensionally and functionally comparable, but preload class and cage type must be matched to the application and none is a Timken-published interchange. Fafnir is a retired brand name: Fafnir super precision became Timken super precision, so the current-production equivalent is ordered as a Timken 2MM9116WI with the preload suffix you need.