SKFNN-3013-AKMC/C481Double-Row Super-Precision Cylindrical Roller Bearing 65 x 100 x 26 mm, 1:12 Tapered Bore, Brass Cage, P5

Product Description

What this part is

An SKF NN 3013 double-row super-precision cylindrical roller bearing, 65 mm bore x 100 mm outside diameter x 26 mm width (2.5591 x 3.9370 x 1.0236 in). Two rows of cylindrical rollers run between a solid outer ring and a triple-ribbed solid inner ring with a 1:12 tapered bore. This is a machine-tool spindle bearing: very high radial rigidity, very high radial running accuracy, no axial location.

Decoding the designation

NN — cylindrical roller bearing, double row.
30 — dimension series.
13 — bore code, 65 mm bore.
A — SKF internal design variant for the series.
K — tapered bore, taper 1:12.
M — machined brass cage, roller-riding.
P5 — ISO tolerance class 5 dimensional and running accuracy, as carried in the listing designation.

What these specs mean in practice

Two rows of cylindrical rollers in a narrow section give this family the highest radial load capacity and radial stiffness available in a bearing of this envelope, which is what a boring, grinding or turning spindle needs to hold a cut. Cylindrical rollers have line contact rather than the point contact of a ball, so deflection under radial load is small. The bearing is a purely radial, non-locating support: axial position of the spindle comes from a separate thrust or angular contact bearing elsewhere in the assembly.

The 1:12 tapered bore mounts directly onto a tapered spindle journal. Driving the inner ring further up the taper expands it, and radial internal clearance falls as it does; this is the standard method of setting preload and running clearance on a machine-tool spindle, adjusted by measurement rather than by ordering a fixed clearance class. The taper mounting also gives a very concentric, repeatable inner-ring seat.

The machined brass cage is stiffer and better damped than a polyamide cage, tolerates higher continuous temperature and mineral-oil-additive chemistry that attacks polyamide, and survives high acceleration and reversal duty. It is heavier than a polyamide cage, so the very highest speed grades of this family use polyamide or PEEK instead.

P5 accuracy sets bore, outside diameter and width tolerances and, more importantly, radial and axial runout of the assembled bearing, to class 5 — roughly an order tighter than a normal-class bearing and the entry point for spindle work.

Published specifications

Bore d: 65 mm (2.5591 in), tapered 1:12
Outside diameter D: 100 mm (3.9370 in)
Width B: 26 mm (1.0236 in)
Basic dynamic load rating C: 76.5 kN (76,500 N / 17,200 lbf)
Basic static load rating C0: 116 kN (116,000 N / 26,080 lbf)
Rows: 2
Approximate mass: 0.72 kg (1.59 lb)

Quantity and configuration

Bearing only. One piece per sale unit. Open, non-locating, no seals or shields.

Fitting notes

The tapered bore seats on a 1:12 tapered spindle journal and is drawn up with a locknut. Axial position on the taper sets the radial internal clearance or preload, so the drive-up distance is measured during assembly. The outer ring is normally a close sliding fit in the housing bore so it can be positioned axially by the housing shoulders and the mating locating bearing.

Interchange guidance

The ISO base number is NN 3013 K. Same-envelope tapered-bore double-row super-precision cylindrical rollers in other schemes include the NSK NN3013TBKRCC0P4 family, the FAG NN3013-AS-K-M-SP, the NTN NN3013K and the Koyo NN3013K. Related sizes rather than interchanges: the NN 3013 TN/SP is the same envelope with a polyamide cage, the NN 3013 has a cylindrical bore in place of the taper, and the NNU 4913 is the same bore in the flanged-outer-ring family.