Fafnir3MM9122WI-2Super-Precision Angular Contact Ball Bearing, Matched Set of Two – 110 mm ID, 170 mm OD, 28 mm Width Each, Open, 25° Contact Angle, ISO P4S

Product Description

What this part is

Fafnir 3MM9122WI-2 super-precision angular contact ball bearing, matched set of two. Manufacturer: Timken. Bore: 110 mm. Outside Diameter: 170 mm. Bearing Width: 28 mm per bearing. Total Width: 56 mm across the set. Rows per Set: one row per bearing. Contact Angle: 25°. Precision Rating: ISO P4S (ABEC 7/9). Cage Type: CR — Phenolic Outer Land Riding Cage. Ball Type: steel. Bearing Material: chrome bearing steel. Closure Type: open. Bore form: straight, low-shoulder outer ring. Series: Fafnir 9100WI, the ISO 7022 section. Timken World Part Number: 7022E-T-P4S. Country of origin: United States.

Published ratings, per bearing

Dynamic Radial Load Rating, 1M revolutions (C1): 103 200 N (23 200 lbf) per bearing. Dynamic Radial Load Rating, ISO C1 per row: 94 100 N (21 200 lbf). Static Radial Load Rating (C0): 97 400 N (21 900 lbf). Limiting Speed, grease: 6 800 rpm. Limiting Speed, oil: 13 600 rpm. These are the single-bearing figures for the 3MM9122WI.

Decoding the designation

3MM: 25° contact angle, super-precision execution. MM: Precision Class P4S. 9122: the 9100WI light dimension series with ISO bore code 22, the 7022 section at 110 x 170 x 28 mm. WI: low shoulder on both rings. Trailing 2: two bearings in the set. The carton also carries the interchange designations 7022-A, 7022 ACD P4A and 7022 A5T P4, all 25° super-precision numbers for this envelope.

What these specs mean in practice

A 25° contact angle is the middle grade of the super-precision range: it carries substantially more thrust than a 15° bearing while still running fast, which suits milling spindles, boring spindles and any position where cutting thrust is significant. The low shoulder on both rings is what allows the ball complement to sit at that angle and lets the bearing be ground and assembled to super-precision tolerance. P4S holds radial and axial runout to a few microns, giving low running vibration and close, repeatable shaft location. Universal grinding means any two bearings of this designation match each other and can be arranged as the spindle requires.

Mounting dimensions

Max Shaft Fillet Radius: 2 mm (0.079 in). Shaft Backing Shoulder Diameter: 122.3 mm (4.820 in). Housing Backing Shoulder Diameter: 158.4 mm (6.240 in). Outer Ring To-Clear Radius: 2.0 mm (0.079 in).

Quantity and configuration

Unit Quantity: 2 Pcs, a matched set. Each bearing measures 110 x 170 x 28 mm; stacked width across the two is 56 mm. Ground for universal mounting, so the pair sets back to back, face to face or in tandem. Sealed in factory wrapping.

Interchange guidance

Direct equivalents on the same 25° super-precision envelope: SKF 7022 ACD/P4A, NSK 7022 A5T P4, FAG B7022-E-T-P4S and the Timken world part number 7022E-T-P4S. Timken lists 3MM9122WI in its machine tool high speed spindle bearing interchange. A 15° bearing on this envelope, such as a 2MM9122WI, is a related size at a different contact angle. Searchable forms: 3MM9122WI-2, 3MM9122WI2, 3MM-9122-WI-2, 3MM 9122 WI 2, 3MM9122WI, 9122WI, 7022.