Fafnir2MM209WICRDUMAngular Contact Ball Bearing – Straight Bore, 45 mm ID, 85 mm OD, 19 mm Width, Open, 15° Contact Angle, Medium Preload, Duplex Universal Pair.

Product Description

What this part is

Fafnir 2MM209WI-CR-DUM super-precision angular contact ball bearing, 200WI spindle range, 45 x 85 x 19 mm. Bore Diameter: 45 mm. Outside Diameter: 85 mm. Overall Width: 19 mm. Total Width: 38 mm. Contact Angle: 15°. Precision Class: ABEC 7/9 / P4S. Dynamic Load Rating: 45,200 N. Static Load Rating: 28,800 N. Limiting Speed: 17,500 rpm grease; 35,000 rpm oil. Preload: Medium. Cage Type: Phenolic outer-land-riding. Cage Material: Phenolic. Rolling Elements: Ball. Bearing Material: Chrome steel. Bore Type: Straight. Closure Type: Open. Number Of Rows: 2. Mounting Arrangement: Universal. Lubricant: grease or oil. Design Units: Metric. Series: 200WI. Base Number: 2MM209WI.

Decoding the designation

2MM — 15° contact angle.

MM — Fafnir super-precision execution, ISO Class P4S, equivalent to ABEC 7/9.

209 — 200 spindle series, 45 mm bore, ISO 7209 envelope.

WI — low shoulder on both rings.

CR — phenolic outer-land-riding cage.

DUM — duplex set of two universally ground bearings at medium preload.

What these specs mean in practice

Contact Angle: 15°. The shallower angle favours speed and radial stiffness over thrust capacity, which is the usual choice for a high-speed spindle position.

Dynamic Load Rating: 45,200 N per bearing, rated over one million revolutions. Static Load Rating: 28,800 N.

Limiting Speed: 17,500 rpm grease; 35,000 rpm oil. Oil feed doubles the ceiling because it carries heat out of the contact as well as lubricating it.

Preload: Medium. Medium preload raises system stiffness above the light setting and holds shaft position more firmly under changing load, at the cost of some speed headroom.

Cage Type: Phenolic outer-land-riding. Guiding the cage on the outer ring land steadies it at speed and gives the lubricant a defined path through the cage pockets.

Rolling Elements: Ball, steel. Precision Class: ABEC 7/9 / P4S, which buys tighter bore, outside diameter and raceway tolerances, closer shaft location and lower running vibration.

Mounting data

Bore Type: Straight. Shaft backing shoulder diameter: 52.3 mm. Housing backing shoulder diameter: 78.2 mm. Maximum housing fillet radius the bearing corners will clear: 1 mm. Outer ring to-clear radius: 1 mm.

Mounting Arrangement: Universal — universally ground faces allow the pair to be set back-to-back, face-to-face or in tandem. The set is preload-established rather than clearance-set.

Quantity and configuration

Unit Quantity: 2 Pcs. One duplex set of two universally ground bearings at medium preload, supplied together as the sale unit. Overall Width: 19 mm per bearing. Total Width: 38 mm, which is the mounted stack height of the pair.

Interchange guidance

Cross-Reference 1: Timken 7209C-T-P4S-DUM. Cross-Reference 2: FAG B7209-C-T-P4S-DUM. Cross-Reference 3: SKF 7209 CD/P4A DGB. Cross-Reference 4: NSK 7209CTRDUMP4. Cross-Reference 5: IBC 7209-C-T-P4S-DUM.

Cross-Reference 6: 3MM209WI-CR-DUM shares the 45 x 85 x 19 mm envelope at a 25° contact angle and is a related size rather than a direct interchange.

Searchable forms of the designation: 2MM209WICRDUM, 2MM209WI-CR-DUM, 2MM 209 WI CR DUM, 2MM209WIDUM, 7209-C, 7209C.