1 Model Information & Technical Parameters

Model：NN 3012 TN/SPW33

 

Basic Dimensions

Parameter Value Unit

Bore diameter (d) 60 mm

Outside diameter (D) 95 mm

Width (B) 26 mm

Inner ring flange diameter (d₁) 73.3 mm

Outer ring raceway diameter (E) 86.1 mm

Width of lubrication groove (b) 3.8 mm

Lubrication hole diameter (K) 2.0 mm

Chamfer dimension (r₁,₂) 1.1 mm

Permissible axial displacement (s max.) 1.5 mm

Bore type Cylindrical —

Accuracy class SP (dimensional accuracy ISO 5, running accuracy approaching ISO 4) —

Radial internal clearance C1 —

Performance Data

Parameter Value Unit

Dynamic load rating (C) 73.7 kN

Static load rating (C₀) 106.0 kN

Fatigue load limit (Pᵤ) 12.7 kN

Limiting speed – grease 9,500 r/min

Limiting speed – oil-air 11,000 r/min

Reference grease quantity (Gref) 3.8 cm³

Axial static stiffness (guideline) 1,330 N/µm

Operating temperature range -30 ~ +110 °C

Bore diameter tolerance -0.009 ~ 0 mm

Outside diameter tolerance -0.010 ~ 0 mm

Width tolerance -0.15 ~ 0 mm

Technical Attributes

Attribute Detail

Bearing type Super-precision double row cylindrical roller bearing

Series NN 30

Number of rows 2

Inner ring design Three flanges (integral ribs)

Outer ring design Flangeless

Cage material PA66 nylon injection moulded cage, roller centred

Roller material Chrome steel

Ring material Chrome steel

Seal type Open (no seals)

Bore type Cylindrical

Accuracy class SP

Radial clearance C1

Separable design Yes (inner and outer rings separable)

Supplementary lubrication feature Annular groove and lubrication holes (W33)

Logistics & Industry Codes

Parameter Value Unit

Net weight 0.643 kg

Indicative carbon footprint 2.4 kg CO₂e

eClass code 23-05-09-01 —

UNSPSC code 31171505 —

Suffix Full Explanation

Suffix Meaning

NN Double row cylindrical roller bearing, high precision series

30 Dimension series (ISO series 30)

12 Bore size code – 60 mm (12 × 5 = 60 mm)

TN PA66 nylon injection moulded cage, roller centred

SP Super Precision class – dimensional accuracy ISO 5, running accuracy approaching ISO 4

W33 Annular lubrication groove and three lubrication holes in the outer ring

Important reminder: This model features a cylindrical bore and can be mounted directly on cylindrical shafts. The W33 lubrication feature provides an annular groove and three lubrication holes in the outer ring, significantly improving lubrication performance. The bearing is open-type without seals and requires external lubrication and sealing protection based on actual operating conditions. Operating temperature range: -30°C to +110°C. The separable design allows independent mounting of inner and outer rings, facilitating assembly and maintenance. The SP accuracy class (dimensional accuracy ISO 5, running accuracy approaching ISO 4) ensures extremely high running accuracy. The three-flange inner ring and flangeless outer ring allow the bearing to accommodate axial displacement in both directions (max. 1.5 mm), effectively compensating for thermal expansion.

 

2 Structure & Operating Characteristics

The NMT NN 3012 TN/SPW33 is a super-precision double row cylindrical roller bearing from the NN 30 series, specifically developed for high-precision, high-rigidity applications such as machine tool spindles. This series achieves a unique balance between load carrying capacity, rigidity and speed.

 

Double row roller design is the core structural feature. Two rows of rollers arranged in parallel distribute loads more evenly across a wider area, significantly increasing the contact area between rollers and raceways. Compared to single row bearings, the double row design offers higher load capacity and rigidity. The line contact between cylindrical rollers and raceways provides high radial load capacity, enabling the bearing to accommodate heavy loads and impact loads while also supporting high-speed rotation. Dynamic load rating reaches 73.7 kN; static load rating reaches 106 kN.

 

Three-flange inner ring and flangeless outer ring design is another key feature. The inner ring features three integral ribs (flanges) while the outer ring has no flanges, allowing the bearing to accommodate axial displacement in both directions. In applications with significant thermal expansion such as machine tool spindles, thermal elongation of the shaft and housing can be compensated through internal axial displacement, with maximum permissible axial displacement of 1.5 mm, without generating additional axial loads.

 

W33 lubrication feature is an important differentiator of this model from standard versions. The W33 suffix indicates an annular lubrication groove and three evenly distributed lubrication holes in the outer ring. This design enables lubricant to reach the raceway area more effectively, significantly improving lubrication performance and extending bearing service life. The lubrication groove width is 3.8 mm and lubrication hole diameter is 2.0 mm.

 

Separable design enables independent mounting of inner and outer rings, which is particularly convenient in interference fit applications – one ring can be mounted first, then the other assembled, greatly simplifying assembly and disassembly.

 

PA66 nylon injection moulded cage (TN suffix) ensures precise roller positioning and stability at high speeds. PA66 material offers excellent wear resistance and low friction characteristics, effectively reducing heat generation and energy consumption. The cage prevents cylindrical rollers from contacting each other, enabling controlled motion of rolling elements with lower friction, thus achieving higher speeds and reduced heat generation.

 

SP Super Precision class is the hallmark of NMT super-precision bearings. SP class bearings achieve dimensional accuracy approximately at ISO 5 level and running accuracy approaching ISO 4 level, ensuring extremely high running accuracy and low vibration levels.

 

Cylindrical bore design allows direct mounting on cylindrical shafts, with simple installation suitable for most standard spindle configurations.

 

3 Core Performance Advantages

1. Extremely high radial load capacity. Double row roller design and cylindrical roller line contact structure enable the bearing to withstand very high radial and impact loads. Dynamic load rating reaches 73.7 kN; static load rating reaches 106 kN. Fatigue load limit reaches 12.7 kN, ensuring long-term reliable operation.

 

2. Superior system rigidity. The unique double row compact configuration of the NN 30 series provides exceptionally high radial stiffness (axial static stiffness up to 1,330 N/µm), making it ideal for precision spindle systems.

 

3. Super-precision running accuracy. SP accuracy class (dimensional accuracy ISO 5, running accuracy approaching ISO 4) ensures ultra-low vibration, ultra-low noise and ultra-low heat generation, meeting high-precision machining requirements.

 

4. W33 lubrication feature – improved lubrication and extended service life. The annular lubrication groove and three lubrication holes in the outer ring enable lubricant to reach the raceway area more effectively, significantly improving lubrication performance and extending bearing service life.

 

5. Bidirectional axial displacement compensation (max. 1.5 mm). The three-flange inner ring and flangeless outer ring design allow the bearing to accommodate axial displacement in both directions during operation, with maximum permissible axial displacement of 1.5 mm, effectively compensating for thermal expansion.

 

6. Separable design for easy assembly and maintenance. Inner and outer rings can be mounted independently, particularly suitable for complex assembly conditions requiring interference fit.

 

7. PA66 nylon cage for excellent high-speed performance. Grease limiting speed: 9,500 r/min; oil-air limiting speed: 11,000 r/min, meeting high-speed spindle requirements. The cage effectively reduces friction and heat generation.

 

4 Typical Application Fields

4.1 Machine Tool Spindles

Machining center spindles (horizontal and vertical), turning center spindles, milling spindles – the combination of high rigidity, high accuracy and high speed is a perfect match.

 

4.2 Precision Grinding Machines

External cylindrical grinder spindles, internal grinder spindles – extremely high radial load capacity and running accuracy ensure machining quality.

 

4.3 Aerospace Engines and Gas Turbines

Aircraft engine main shafts, gas turbine rotor supports – high strength and reliability meet aerospace requirements.

 

4.4 High-Performance Automotive and Racing

High-performance automotive transmissions, racing gearboxes, high-speed drive units.

 

4.5 Industrial Gearboxes and Reducers

High-speed gearboxes, reducers – stable performance under heavy loads and high speeds.

 

4.6 Robotics and Automation Systems

High-precision positioning units, automation system rotary supports – high rigidity support ensures motion accuracy.

 

5 Assembly Specifications & Usage Guidelines

5.1 Pre-installation Inspection

Verify model and specifications match design requirements. Inspect bearing appearance to ensure no damage, corrosion or foreign matter. Check shaft dimensional accuracy against design specifications (cylindrical bore design suitable for cylindrical shafts). Prepare appropriate mounting tools. Recommended shaft abutment minimum diameter is 66.5 mm; housing abutment minimum diameter is 87 mm, maximum is 88.5 mm.

 

5.2 Installation Procedure

This bearing features a cylindrical bore and can be mounted directly on cylindrical shafts. Use press-fit method or shrink-fit method for installation, with force applied evenly to the end face of the fitted ring. Never apply force through rolling elements or cage. The separable design allows independent mounting of inner and outer rings – the outer ring can be mounted in the housing first, then the inner ring on the shaft, or vice versa.

 

5.3 Using the W33 Lubrication Feature

This bearing features an annular lubrication groove and three lubrication holes (W33) in the outer ring. During installation, ensure that the lubrication channels in the housing align with the lubrication holes in the bearing outer ring for effective lubricant delivery. Lubrication hole diameter is 2 mm; lubrication groove width is 3.8 mm.

 

5.4 Clearance Information

This bearing has a cylindrical bore with C1 radial clearance. C1 clearance is suitable for high-speed operation and applications with significant temperature variations.

 

5.5 Lubrication Maintenance

This model comes without pre-filled grease – lubricant must be added during installation based on operating conditions. Grease limiting speed is 9,500 r/min; oil-air limiting speed is 11,000 r/min. Reference grease quantity is 3.8 cm³. The W33 lubrication feature enables lubricant to reach the raceway area more effectively through the outer ring lubrication holes. High-quality spindle grease or circulating oil is recommended. Open construction requires reliable sealing protection at the equipment level. Establish regular lubrication replenishment schedule; dry running is strictly forbidden.

 

5.6 Environmental Considerations

Operating temperature range: -30°C to +110°C. As this bearing is open construction, in dusty environments or coolant splash conditions, labyrinth seals or contact seals must be provided at the equipment level. The bearing itself does not carry axial loads; axial displacement (max. 1.5 mm) is accommodated by the external structure. Ensure that axial displacement does not cause interference between the bearing and other components. Maximum chamfer radius is 1.0 mm.

 

6 Fault Identification

Common failure modes: Roller or raceway fatigue pitting, abnormal operating noise increase, significant rotation resistance increase, excessive temperature rise, seizure caused by poor lubrication. Blocked W33 lubrication holes may lead to lubrication failure – regularly inspect lubrication channels for. If cage deformation or rolling element damage occurs, replace the entire bearing assembly – repair and reuse are not allowed. Regularly monitor bearing temperature and vibration for early detection of abnormalities.