Fafnir2MM218WIDULSuper Precision Angular Contact Ball Bearing 90x160x30 mm, 15° Contact Angle, Duplex Light Preload, Phenolic Cage, 2 Pcs

Product Description

What this part is

A matched pair of Fafnir super-precision angular contact ball bearings, part number 2MM218WI-DUL. Bore is 90 mm, outside diameter 160 mm and each ring width 30 mm, giving an ISO 7218 envelope. Fafnir is the super-precision line of the Timken Company, and the WI family is its spindle-grade angular contact series.

Decoding the designation

The leading 2 of 2MM sets a 15° contact angle, where a 3MM prefix sets 25°. The MM prefix carries super-precision class P4S, ABEC 7 dimensionally with ABEC 9 running accuracy. The absence of a leading 9 in 218 places the bearing in the ISO 72 dimension series rather than the lighter 70 series, which is why the outside diameter is 160 mm rather than the 140 mm of a 7018. WI identifies the super-precision angular contact family and CR on the carton marks a phenolic cage riding on the outer ring land. DU is a universally ground duplex pair and L is light preload.

What these specs mean in practice

A 15° contact angle carries less thrust and permits higher speed than a 25° angle. Light preload eliminates internal clearance while keeping running torque and heat generation low, which suits high-speed spindle positions where thermal growth governs. A phenolic cage riding on the outer land has low mass and a favourable friction pair against steel, and it retains oil in the cage material, which is why the CR cage is standard on high-speed super-precision spindle bearings; its working temperature ceiling is lower than a bronze or steel cage.

Quantity and configuration

2 Pcs, supplied as one duplex pair ground for light preload. No spacer rings, lock nut or housing are included.

Fitting notes

Universally ground rings reach the designed preload when the pair is clamped solid against the flush ground faces, without shimming, and the arrangement is set by which faces are brought together. Handling is by the outer ring on a clean surface, and a phenolic cage is kept clear of solvents that attack the resin.

Interchange guidance

Same-spec equivalents are the 7218 C P4 DUL forms: FAG B7218-C-TPA-P4S-UL, SKF 7218 CD/P4A in a light-preload duplex arrangement, NSK 7218 CTR DUL P4 and RHP 7218CTDULP4. The Barden 218HDL is the equivalent in the Barden inch-scheme numbering. A 7218 AC or A5 variant is a related size at 25° or 30° and changes the thrust and speed balance, so it is not a substitution.