Fafnir3MM9112WIDUC2Super Precision Angular Contact Ball Bearing Duplex Pair – Straight Bore, 60 mm ID, 95 mm OD, 18 mm Width Each, Open, 25° Contact Angle, Light Preload, Phenolic Outer-Land-Riding Cage, ISO P4S

Product Description

What this part is

Fafnir 3MM9112WI DUL matched duplex pair of super precision angular contact ball bearings, 9100WI spindle series. Manufacturer Part Number: 3MM9112WI DUL. World Part Number: 7012E-T-P4S-DUL. Bore: 60 mm. Outside Diameter: 95 mm. Bearing Width: 18 mm per bearing. Total Width: 36 mm for the pair. Number Of Rows: 1 per bearing. Bore Type: Straight. Closure Type: Open. Rolling Elements: Steel balls. Design Units: Metric.

Decoding the designation

Contact Angle: 25°, carried by the 3MM prefix. Series: 9100WI, which maps to the ISO 70xx light section, so the 9112 is a 7012 envelope at 60 x 95 x 18 mm. WI: low shoulder on both rings. CR: phenolic outer land riding cage. DU: duplex, a factory-matched two-bearing set. L: light preload. Precision Class: ISO P4S, equivalent to ABEC 7/9. Preload: Light. Mounting Arrangement: Duplex pair.

Published ratings

Dynamic Radial Load Rating – 1M Revs (C1): 36,900 N (8,290 lbf) per bearing. C1 ISO Dynamic Radial Rating, per row: 33,500 N (7,540 lbf). Static Radial Load Rating (C0): 29,100 N (6,550 lbf) per bearing. Limiting Speed, grease: 13,500 rpm. Limiting Speed, oil: 24,400 rpm.

Mounting dimensions

Max Shaft Fillet Radius: 1 mm. Outer Ring To Clear Radius: 1 mm. Shaft Backing Shoulder Diameter: 67.3 mm. Housing Backing Shoulder Diameter: 88.1 mm.

What these specs mean in practice

A 25° contact angle puts more of the load line along the shaft axis, so this pair is stiffer axially than the 15° execution on the same envelope and holds a spindle nose in position under thrust — boring, drilling, plunge milling, heavy face milling. The trade is speed: a steeper angle raises the centrifugal and gyroscopic work on the ball set.

Light preload is the setting for speed and low heat generation. It gives less axial stiffness than a medium or heavy set and lets the spindle run cooler at the top of its range. Internal Clearance: N/A — a preloaded set is defined by its preload rather than by a clearance class.

Cage Type: CR, phenolic outer land riding. Cage Material: Phenolic. A machined phenolic laminate cage is light, so it loads the ball pockets very little at speed, it is self lubricating, and it damps rather than rings. Guidance on the outer ring land keeps it stable at high speed. Lubricant: grease or oil, and Timken publishes a limiting speed for each.

Quantity and configuration

Unit Quantity: 2 Pcs. A factory-matched duplex pair, ground as a set to the light preload. The two bearings ship together and are the sale unit, giving a 36 mm total stack width.

Interchange guidance

Base Number: 7012. MPN Variants: 3MM9112WIDUL, 3MM9112WI DUL, 3MM-9112-WI-DUL, 3MM9112WICRDUL, 3MM9112WIDUC2, 3MM-9112-WI-CR-DU-C2, 7012, 7012A. Same-envelope 25° light-preload duplex equivalents are written SKF 7012 ACDGA/P4A, FAG B7012-E-T-P4S-DUL and NSK 7012A5. Cage material and precision class vary between makers inside those designations. The line passed from Fafnir to Torrington to Timken, and Timken lists 3MM9112WI DUL today.