SKF
Double Row Cylindrical Roller Bearings
Double row cylindrical roller bearings feature two roller paths in a single bearing, providing higher radial load capacity and rigidity than single row types without increasing bore diameter. SKF offers designs in NN, NNU, and NNF series, primarily used in machine tool spindles, rolling mill roll necks, and industrial gearboxes. They excel where radial space is limited but extreme radial stiffness is demanded. NN and NNU designs have a separable inner ring, allowing easier mounting and high precision, while NNF designs include integral flanges for location. Most double row cylindrical roller bearings are produced with higher precision (SP, P4) and are ideal for super-precision and high-speed applications. SKF Explorer quality ensures superior running accuracy and longer service intervals.
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High Radial Stiffness
Double roller row supports heavy loads with minimal deflection.
Separable Ring Design (NN, NNU)
Enables radial preload adjustment and easy mounting.
High Precision
Typically supplied in P5, SP, and P4 accuracy grades for spindle applications.
Compact Radial Envelope
Fits standard single row width but boosts capacity.
Grease and Oil Lubrication Ready
Optimized lubricant flow paths for high-speed oil systems.
Maintenance-Friendly
Removable inner ring simplifies regrinding of spindle shaft.
NN and NNU Series in Machine Tool Spindles
Double row cylindrical roller bearings with tapered bore (NNU 49 series) are a staple in lathe, milling, and grinding spindles. Their ability to be radially preloaded, combined with high precision, delivers the necessary cutting stiffness while maintaining thermal stability at high speeds.
Double Row Cylindrical vs. Spherical Roller Bearings
While spherical roller bearings offer misalignment compensation, double row cylindrical bearings provide higher radial stiffness and speed capability. In applications with well-aligned housings like a gearbox, double row cylindrical bearings yield better precision and longer life.