FafnirM307KCRPrecision Spindle Deep Groove Ball Bearing – 35 mm Bore, 80 mm OD, 21 mm Width, ABEC 3 / P6, Phenolic Cage

Product Description

What this part is

Fafnir M307KCR, a precision spindle deep groove ball bearing. Bore Diameter: 35 mm. Outside Diameter: 80 mm. Overall Width: 21 mm. Rolling Elements: Ball. Number Of Rows: 1. Bore Type: Straight. Closure Type: Open. Cage Material: Phenolic. Precision Class: ABEC 3 / P6. Internal Clearance: CN. Bearing Material: Chrome steel. Series: 300K. Base Number: M307K.

Decoding the designation

M — Fafnir precision spindle range at P6 tolerance, one class above standard. The doubled MM prefix marks the P4S range; a single M is the P6 grade.

307 — 300 heavy dimension series, bore code 07: a 35 mm bore in an 80 mm outside diameter.

K — spindle deep groove construction. Conrad-type raceways carry radial load and axial load from either direction, so the bearing has no contact angle.

CR — phenolic cage.

What these specs mean in practice

Precision Class: ABEC 3 / P6 gives tighter bore, outside diameter and running-accuracy tolerances than a standard 6307, which shows up as lower runout and quieter running at speed. A phenolic cage is light and absorbs vibration, so it suits higher shaft speeds than a pressed-steel cage on the same envelope. Internal Clearance: CN, the normal grade, with no clearance code on the carton.

Quantity and configuration

Unit Quantity: 1 Pc. One single-row bearing.

Interchange guidance

The envelope is the ISO 6307 envelope, 35 x 80 x 21 mm. FAG 6307-TB-P6, NSK 6307P6, NTN 6307P6 and Koyo 6307P6 are the direct tolerance-class equivalents. Timken MM307K is the same geometry in the tighter P4S class. A standard-tolerance 6307 from any maker shares the envelope in a looser accuracy class. Searchable variants include M307KCR, M-307-K-CR, M 307 K CR and M307K.