FAGNN3007ASKMSPW33Double Row Super Precision Cylindrical Roller Bearing, 35 x 62 x 20 mm, 1:12 Tapered Bore, Brass Cage, P5

Product Description

What this part is

A double row super-precision cylindrical roller bearing at the NN3007 envelope: 35 mm bore, 62 mm outside diameter, 20 mm wide. Two rows of small cylindrical rollers, a triple-ribbed inner ring, a machined brass cage and a 1:12 tapered bore. This is not a general-purpose roller bearing — it is a machine-tool spindle bearing, and almost every design choice in it serves one goal: maximum radial stiffness with minimum runout at high speed.

Decoding the designation

NN — double row cylindrical roller bearing with a ribbed inner ring (the NN prefix denotes the two-row design with inner-ring ribs guiding the rollers).3007 — 30 dimension series, bore code 07 (35 mm).K — 1:12 tapered bore. Not cosmetic: it is the preload-adjustment mechanism.M — machined brass cage.SP — super-precision, P5 accuracy class in the ISO tolerance system.

The tapered bore is how you set preload — and that is the whole point:
A cylindrical-bore bearing gives you whatever clearance the interference fit happens to leave. A tapered-bore NN gives you control. Mounted on a tapered spindle seat or a sleeve, driving the inner ring up the 1:12 taper expands it, which progressively reduces radial internal clearance and then, past zero, applies radial preload. Drive-up distance is measurable, so the resulting clearance or preload is a number you set rather than a number you inherit.

That is why these appear in spindles. Radial preload eliminates the clearance in which a spindle would otherwise deflect and chatter, so the spindle holds its position under cutting load and the machine holds tolerance. It also means the bearing is unforgiving of a careless mounting: over-drive it and you have a preloaded bearing generating heat it cannot shed, which grows the inner ring, which increases preload further. Under-drive it and you have paid for P5 accuracy and thrown away the stiffness it was bought for. Reduction in radial internal clearance must be measured during mounting — a torque figure on a nut is not a substitute.

What P5 accuracy and the brass cage buy you:
P5 controls bore and outside diameter tolerance, and critically radial and axial runout, far more tightly than the normal P0 class. In a spindle, bearing runout transfers directly to the tool or workpiece, so accuracy class is not a quality upgrade — it is the specification the machine’s achievable tolerance was calculated from. Fitting a P0 bearing into a P5 spindle position gives you a machine that runs and cuts badly, in ways that are hard to diagnose because nothing is broken.

The machined brass cage matters at these speeds. Brass is dimensionally stable, tolerates the temperatures a preloaded high-speed bearing reaches, and works with oil-mist and oil-jet lubrication systems that polymer cages tolerate poorly. It also allows the roller complement and pocket geometry to be machined to the accuracy the rest of the bearing is held to.

Published ratings for this envelope

Bore (d): 35 mm, tapered 1:12Outside diameter (D): 62 mmWidth (B): 20 mmDynamic radial load rating Cr: 38,000 NStatic radial load rating C0r: 47,500 NMaximum speed, grease: 14,300 rpmMaximum speed, oil: 17,300 rpmAccuracy class: P5 (SP)Cage: machined brass (M)Inner ring: triple ribbedNumber of rows: 2Approx. weight: 0.235 kg
Figures are published for the NN3007K/SP super-precision build at this envelope. Note the speed capability: 14,300 rpm in grease from a 62 mm outside diameter roller bearing is only achievable because of the precision grade and the brass cage — a standard-class equivalent would not approach it.

A note on the brand marking

We are flagging this rather than papering over it. This record carries a title reading SKF and a brand field reading FAG, and the /SP and K-M-SP suffix conventions are used by both manufacturers for super-precision builds at this envelope. We cannot resolve which brand this unit actually is from the record alone, and changing the brand field on a guess would be worse than saying so. The bearing’s specification is not in doubt — NN3007K M SP describes the same design and the same published ratings whichever of the two made it. If the brand matters for your approved-vendor list, ask us and we will read the ring marking before you order.

Quantity, configuration and fitting notes

One bearing in stock; a complete bearing, both rings, both roller rows and the brass cage. No sleeve or spindle nut is included. Tapered-bore super-precision bearings are normally mounted with a hydraulic or measured mechanical drive-up and the residual clearance or preload verified by measurement. Handle it as a precision component: clean assembly area, no impact, press only on ring faces, and match the lubricant to the speed regime you intend to run.

Interchange guidance

Search forms include NN3007KMSP, NN3007K-M-SP, NN3007 K M SP, NN3007K/SP, NN3007KSP, NN3007K, NN3007, NN 3007 K/SP. Related builds: NN3007/SP (cylindrical bore, same envelope), NN3007K/UP (ultra-precision, P4), NN3007K W33, and the P4/P5 equivalents from NSK, NTN (NN3007K), Koyo and IKO. Verify bore type (tapered K vs cylindrical) and accuracy class (SP/P5 vs UP/P4) before substituting — both are the reason the bearing was specified.