Fafnir2MM220WI-DUMSuper-Precision Angular Contact Ball Bearing Duplex Pair – Straight Bore, 100 mm ID, 180 mm OD, 34 mm Width, 68 mm Stacked, Open, 15° Contact Angle, Medium Preload, Phenolic Cage.

Product Description

What this part is

Fafnir 2MM220WI-DUM super-precision angular contact ball bearings, 200 series, supplied as a matched duplex pair. Brand: Fafnir (Timken). Part Number: 2MM220WI-DUM. Bore: 100 mm. Outside Diameter: 180 mm. Overall Width: 34 mm per bearing. Total Width: 68 mm for the mounted pair. Design Units: Metric. Number Of Rows: 1 per bearing. Rolling Elements: Steel ball. Bore Type: Straight. Closure Type: Open. Bearing Material: Chrome bearing steel. Item Weight: 7.30 lbs.

Decoding the designation

Contact Angle: 15°. Precision Class: P4S. Precision Rating: ABEC 7/9. Cage Material: Phenolic. Cage Type: CR – phenolic outer land riding. Preload: Medium. Arrangement / Configuration: Duplex, universally ground. Series: 200, carrying the ISO 7220 envelope. Timken World Part Number: 7220C-T-P4S-DUM.

Load ratings and speeds

Dynamic Radial Load Rating (C1), per bearing: 165,200 N (37,100 lbf). Dynamic Radial Load Rating (C1 ISO, per row): 150,000 N (33,700 lbf). Static Radial Load Rating (C0), per bearing: 126,800 N (28,500 lbf). Limiting Speed, grease: 8,000 rpm. Limiting Speed, oil: 16,000 rpm.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity, which is the usual choice for a machine tool spindle. The medium preload class sits between the light class used for maximum speed and the heavy class used for maximum stiffness. The phenolic cage rides on the outer ring land, staying centred at speed and holding lubricant against the ball pockets. Oil feed doubles the speed ceiling over grease at this size. Internal Clearance: N/A — the set is established by preload rather than by clearance.

Mounting data

Shaft Backing Shoulder Diameter: 114.4 mm (4.510 in). Housing Backing Shoulder Diameter: 166 mm (6.540 in). Maximum Shaft Fillet Radius: 2.1 mm (0.079 in). Outer Ring “To Clear” Radius: 2.1 mm (0.079 in).

Quantity and configuration

Unit Quantity: 2 Pcs. Mounting Arrangement: Duplex, universally ground. Two bearings, ground as a matched set, stacking to a 68 mm total width and delivering the medium preload class directly.

Interchange guidance

Cross-References: SKF 7220 CD/P4A, NSK 7220C, Timken 7220C. Each shares the 100 x 180 x 34 mm envelope and the 15° contact angle. Harmonization Code: 8482.10.50.

Designation variants

MPN Variants: 2MM220WI-DUM, 2MM220WIDUM, 2MM 220 WI DUM, 2MM-220-WI-CR-DUM, 2MM220WICRDUM, 7220C-T-P4S-DUM, 7220C, 2MM220WI.