SKF standard ultra-precision double row cylindrical roller bearings with NN30 design and NNU49 series
Both series are available with cylindrical bore or 1:12 tapered bore (type suffix K). In machine tool applications,
cylindrical roller bearings with tapered bores are preferred over those with cylindrical bores because the taper
allows for more precise adjustment of clearance or preload during mounting.
The NN30 series shafts provide a unique balance between load carrying capacity, stiffness and speed. As a result,
they are often used as non-tool end bearings used in machine tool spindles.
The NN30 series bearings have an inner ring with three integral retaining edges and an outer ring without retaining
edges.
NNU49 series bearings have a very low cross-sectional height, which can provide higher stiffness than NN30 series
bearings, but their load capacity is lower.
NNU49 series bearings have an outer ring with three integral retaining edges and an inner ring without retaining
edges.
For effective lubrication, all bearings of the NNU49 and NN30 series with a bore diameter d ≥ 140 mm have an annular
groove in the outer ring and three lubricating holes (model number suffix W330)
Bearings without annular grooves and lubrication holes are usually lubricated with the minimum necessary amount of
grease or precisely measured small amounts of oil or oil-air lubrication. In this case, the Lubrication is usually provided
by a nozzle located on the bearing side.
If an NN30 series bearing with a bore diameter d ≤ 130 mm requires an annular groove and lubrication holes, please
contact SKF as early as possible in the design phase for availability.
