Fafnir2MM9117WI-SUMSpindle Angular Contact Ball Bearing – 85 mm ID, 130 mm OD, 22 mm Width, Open, 15° Contact Angle, Machined Phenolic Cage, Medium Preload, Universal Single.

Product Description

What this part is

Timken Fafnir 2MM9117WI-SUM super-precision angular contact ball bearing, 85 mm bore by 130 mm outside diameter by 22 mm width. Open on both faces, steel balls in a machined phenolic cage riding on the outer ring lands. The ISO equivalent designation is 7017 C.

Decoding the designation

The leading 2MM denotes a 15° contact angle, and the MM prefix itself carries the P4S accuracy class — ABEC 7 dimensional tolerance with ABEC 9 running accuracy. The 9 that opens 9117 places the bearing in the Fafnir 9100 series, which maps to the ISO 70 light series, so 9117 corresponds to a 7017 envelope. WI is the machined phenolic outer-land-riding cage execution. SUM is a single universally ground bearing at medium preload.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness and carries less axial load than a 25° bearing of the same envelope, which is why it dominates machine tool spindle positions. Basic dynamic load rating is 59.6 kN (13 400 lbf) and basic static load rating 55.6 kN (12 500 lbf). Limiting speed is 13 000 r/min, with a running accuracy of 0.0025 mm radial and axial runout. The phenolic cage is light and self-lubricating and sets the 121 °C ceiling.

Quantity and configuration

One piece. Universally ground, so it can be stacked with further SUM bearings of the same designation in back-to-back, face-to-face or tandem sets, and medium preload is then established by the ground ring faces.

Fitting notes

Preload is built into the ground faces, so a stack is clamped solid against the shaft and housing shoulders without shims. Oil or grease lubrication both apply within the published limiting speed.

Interchange guidance

Same-specification equivalents at 15° and medium preload are the SKF 7017 CDGB/P4A and the NSK 7017CTRSUMP4. The 2MM9117WI-SUL and 2MM9117WI-SUH share the envelope at light and heavy preload and are related sizes rather than interchanges, as preload sets spindle stiffness and thermal headroom.