Fafnir2MM9111WI-DULSuper-Precision Angular Contact Ball Bearing Duplex Pair – Straight Bore, 55 mm ID, 90 mm OD, 18 mm Width, Open, 15° Contact Angle, ABEC 7/9, Light Preload, 2 Pcs

Product Description

What this part is

Fafnir 2MM9111WI-DUL super-precision angular contact ball bearing set, ISO 7011 envelope, 55 mm bore x 90 mm outside diameter x 18 mm width per bearing. Bore: 55 mm. Outside Diameter: 90 mm. Overall Width: 18 mm. Total Width: 36 mm across the pair. Bore Type: Straight. Number Of Rows: 1 per bearing. Rolling Elements: Steel balls. Closure Type: Open. Contact Angle: 15°. Precision Class: ABEC 7/9 (ISO P4S). Preload: Light. Cage Material: Machined laminated phenolic. Cage Type: Outer-ring land-riding, machined. Design Units: Metric. Material: High-carbon chrome steel. Country of Origin: United States.

Decoding the designation

2MM: 15° contact angle in Timken’s Fafnir super-precision scheme, and the MM prefix carries ISO tolerance class P4S, equal to ABEC 7/9. 9111: the 9100WI light series, which maps to ISO 7011. WI: super-precision spindle execution. DU: universally faced duplex pair. L: light preload. Timken’s own world part number for this set is 7011C-T-P4S-DUL. Searchable variants: 2MM-9111-WI-DUL, 2MM9111WI DUL, 2MM9111WICRDUL, 7011C, 7011-C.

What these specs mean in practice

Dynamic Radial Load Rating, set: 37,800 N (8,500 lbf). Dynamic Radial Load Rating per row, ISO C1: 34,400 N (7,730 lbf). Static Radial Load Rating: 28,600 N (6,420 lbf). Limiting Speed, grease lubrication: 14,700 rpm. Limiting Speed, oil lubrication: 29,400 rpm. A 15° contact angle favours speed and radial stiffness over thrust capacity, which is why it dominates high-speed spindle work. The machined phenolic cage rides on the outer-ring land, so cage guidance comes from the stationary ring and stays stable as speed rises. Lubricant: grease or oil. Factory grease fill option: Kluberspeed BF72-22.

Quantity and configuration

Unit Quantity: 2 Pcs. Rows Per Set: Duplex. A matched pair with universally ground faces, so the two bearings mount back-to-back, face-to-face or in tandem and reach light preload when clamped. Internal Clearance: N/A — face grinding sets the axial position on a universally faced preloaded set, in place of a radial clearance class.

Fitting notes

Shaft Backing Shoulder Diameter: 62.2 mm (2.450 in). Housing Backing Shoulder Diameter: 83.3 mm (3.280 in). Maximum Shaft Fillet Radius: 1 mm (0.039 in). Outer Ring To-Clear Radius: 1 mm (0.039 in).

Interchange guidance

Same-specification equivalents: Timken world part number 7011C-T-P4S-DUL, NSK 7011CTRDULP4, SKF 7011 CD/P4ADGA, FAG B7011-C-T-P4S-UL, RHP 7011CTDULP4. A 3MM9111WI set shares the 55 x 90 x 18 mm envelope at a 25° contact angle, which is a related size rather than a substitution.