Double Row Super-Precision Cylindrical Roller Bearings
NN and NNU double row super-precision cylindrical roller bearings are used in spindle and precision machinery arrangements where high radial rigidity, accurate running performance, and stable load support are required. Compared with single row N 10 series bearings, double row designs provide greater radial stiffness and higher load carrying capacity for demanding spindle positions.
This category includes NN 30 series and NNU 49 series double row cylindrical roller bearings, with SKF interchangeable models such as NN 3012 KTN/SP, NN 3016 KTN/SPW33, NN 3020 KTN/UP, NNU 4920 BK/SPW33, and NNU 4960 B/SPW33. Available configurations include cylindrical bore, tapered 1:12 bore, super-precision grades, and lubrication groove options.
This page is intended for buyers selecting double row super-precision spindle bearings where rigidity and radial load support are more important than a compact single row bearing layout. For high-speed single row spindle positions or rotary table axial-radial support, TFL can help direct you to the correct parallel super-precision bearing category.
Double Row Design for Higher Spindle Rigidity
Double row super-precision cylindrical roller bearings are selected when the spindle or precision shaft requires higher radial stiffness than a single row bearing can provide. The two rows of cylindrical rollers help improve radial load distribution and support a more rigid bearing arrangement in machine tool spindle systems.
The NN 30 series is widely used in precision spindle applications where high running accuracy, stable radial support, and controlled internal clearance are important. Models such as NN 3012 KTN/SP, NN 3016 KTN/SPW33, NN 3020 KTN/SP, and NN 3026 KTN/UP are common search and replacement references.
This page should not be positioned as a general high-speed single row bearing page. The main selection reason for this category is radial rigidity and spindle stiffness, especially in grinding machines, machining centers, precision lathes, milling machines, and other equipment where the spindle must resist radial deflection under load.
NN 30 Series vs NNU 49 Series Selection
The double row super-precision range includes both NN 30 series and NNU 49 series bearings. The NN 30 series is commonly used in machine tool spindle arrangements, while the NNU 49 series is often selected for larger bearing positions, heavier radial loads, or equipment requiring a wider diameter range.
In the product data, the range includes compact models such as NN 3005 K/SP and NN 3006 KTN/SP, as well as larger models such as NNU 4964 BK/SPW33, NNU 49/500 BK/SPW33X, and NNU 49/670 B/SPW33X. This makes the category suitable for both standard precision spindle replacement and larger precision machinery applications.
When selecting between NN and NNU designs, buyers should compare the bore diameter, outside diameter, width, bore type, load rating, permissible axial displacement, and lubrication configuration. TFL can help confirm whether your old SKF bearing number belongs to the NN 30 series or the NNU 49 series before quotation.
SP, UP and W33 Options for Precision Bearing Replacement
Suffixes are especially important for double row super-precision cylindrical roller bearings. Common suffixes in this category include SP, UP, W33, SPW33, UPW33, VQ497, VR521, and VR522. These suffixes may relate to precision class, lubrication features, vibration or running accuracy requirements, and special internal configurations.
Models with W33 typically include an annular lubrication groove and lubrication holes in the outer ring. This is important for spindle and precision machinery applications where oil or grease distribution must be managed through the bearing arrangement. The product data includes fields such as lubrication groove width and lubrication hole diameter for this reason.
When replacing an SKF bearing, buyers should avoid selecting only by the basic model number. For example, NN 3016 KTN/SP, NN 3016 KTN/SPW33, and NN 3016 KTN/UP may not be interchangeable in every application. TFL can help verify the complete suffix, bore type, lubrication design, and precision requirement before supply.
FREQUENTLY ASKED QUESTIONS
What is the difference between single row and double row super-precision cylindrical roller bearings?
Single row bearings are usually selected for compact high-speed spindle positions. Double row super-precision cylindrical roller bearings are selected when the application requires higher radial rigidity, stronger load support, and improved spindle stiffness.
What are NN and NNU series bearings used for?
NN series bearings are commonly used in machine tool spindle arrangements requiring high radial accuracy and rigidity. NNU series bearings are often used for larger precision machinery positions or heavier radial load applications.
What does W33 mean on double row cylindrical roller bearings?
The suffix W33 usually indicates an annular lubrication groove and lubrication holes in the outer ring. This feature helps distribute lubricant in spindle or precision machinery arrangements where controlled lubrication is required.
Can TFL supply SKF interchangeable NN and NNU bearings?
Yes. TFL can supply SKF interchangeable NN and NNU double row super-precision cylindrical roller bearings. Customers can provide the SKF model, old bearing marking, drawing, or bearing photo for confirmation.
Why is the complete suffix important for NN and NNU bearings?
The complete suffix may indicate precision class, bore type, lubrication groove design, special running accuracy, or internal configuration. Models with similar base numbers may not be interchangeable if the suffix is different.