FafnirMM314KCRPrecision Spindle Deep Groove Ball Bearing 70x150x35 mm, Open Both Faces, Phenolic Cage, 1 Pc

Product Description

What this part is

A Fafnir precision spindle deep groove ball bearing, part number MM314KCR. Bore is 70 mm, outside diameter 150 mm and width 35 mm, giving an ISO 6314 envelope. Both faces are open. Fafnir is the super-precision line of the Timken Company, and the MM spindle series is produced to super-precision tolerances rather than standard bearing class.

Decoding the designation

The MM prefix carries super-precision class P4S, which is ABEC 7 dimensionally with ABEC 9 running accuracy. A bare MM without a leading 2 or 3 carries no contact-angle designation, and the K places the bearing in the Fafnir spindle deep groove families, the 9100K, 200K and 300K blocks, rather than in the WI angular contact range. 314 is the ISO 63 dimension series number, which is why the envelope matches a 6314 and the outside diameter is 150 mm on a 70 mm bore. CR marks a phenolic cage riding on the outer ring land.

What these specs mean in practice

A deep groove bearing takes radial load and thrust in both directions from a nominally radial contact, so it locates a shaft axially without a preloaded pair, and it tolerates a small amount of misalignment. Built to P4S it holds bore, outside diameter and running accuracy to spindle tolerances, which is what suits it to a spindle rear-bearing position where the front position carries a preloaded angular contact set. A phenolic land-riding cage has low mass and retains oil in the resin, at a lower working temperature ceiling than a bronze or steel cage.

Quantity and configuration

1 Pc. Single bearing, open both faces. No shield, seal, snap ring, spacer or lock nut is included.

Fitting notes

Mounting force is applied to the ring being fitted and never transmitted through the balls. Open faces mean lubrication and sealing are provided by the housing arrangement. In a spindle the deep groove position is normally the floating one, so the outer ring is given a clearance fit in the housing bore to allow axial travel with thermal growth.

Interchange guidance

Same-envelope precision equivalents are the 6314 P4 forms, including the NSK 6314 P4 and FAG 6314-P5 or -P4 grades. A standard-class 6314 shares the envelope but not the running accuracy or bore and outside diameter tolerances, so it is a related size rather than a substitution in a spindle position. A 6314-2RS or -ZZ variant adds a seal or shield and changes the speed and temperature envelope.