Fafnir2MM9115WIDULSuper Precision Angular Contact Ball Bearing 75x115x20 mm, 15° Contact Angle, Duplex Light Preload, 2 Pcs

Product Description

What this part is

A matched pair of Fafnir super-precision angular contact ball bearings, part number 2MM9115WI-DUL. Bore is 75 mm, outside diameter 115 mm and each ring width 20 mm, giving an ISO 7015 envelope in the light dimension series. Fafnir is the super-precision line of the Timken Company.

Decoding the designation

The leading 2 of 2MM sets a 15° contact angle; a 3MM prefix would set 25°. The MM prefix carries super-precision class P4S, which is ABEC 7 on dimensional tolerance with ABEC 9 running accuracy. The leading 9 in 9115 places the bearing in the ISO 70 light series rather than the heavier 72 series, so the 115 mm outside diameter is smaller than a 7215 of the same bore. WI is the super-precision angular contact family. DU is a universally ground duplex pair and L is light preload, with M and H the medium and heavy steps.

What these specs mean in practice

A 15° contact angle carries less thrust and permits higher speed than a 25° angle, and light preload keeps running torque and heat generation low while still eliminating internal clearance. The combination suits high-speed spindle positions where thermal growth matters more than absolute stiffness. The 70 light series gives a thinner cross-section for the same bore, which lowers mass and raises limiting speed at the cost of load capacity.

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. The arrangement is set by which faces are brought together, so the same pair mounts back to back, face to face or in tandem. Handling is by the outer ring on a clean surface.

Interchange guidance

Same-spec equivalents are the 7015 C P4 DUL forms: SKF 7015 CD/P4A in a light-preload duplex arrangement, FAG B7015-C-T-P4S-UL and NSK 7015 CTR DUL P4. A 7015 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. 2MM9115WI-DUM and 2MM9115WI-DUH share the envelope and angle at higher preload.