1 Model Information & Technical Parameters

Model：NN 3012 TN/SPW33

Dimensions

Bore d：60 mm

Outer diameter D：95 mm

Width B：26 mm

Bore type: Straight cylindrical bore

Radial clearance: C1 minimal internal clearance

Accuracy class: SP precision grade

Structure: NN double row design, inner ring with three ribs, ribless outer ring

Outer ring flange: None

Seal: Open design, no seals

Surface coating: Uncoated

Pre-lubrication: No lubricant supplied from factory

Re-lubrication feature: Outer ring with W33 circumferential lubrication groove and through oil holes

Code Explanation

NN: Double row cylindrical roller bearing, three ribs on inner ring. Rollers are restrained axially and able to withstand slight bidirectional axial loads.

3012: Size series 30 medium cross-section double row bearing, balancing high rigidity and medium-high speed performance.

TN: Solid polyamide non-metallic roller-guided cage featuring low friction and low noise.

SP: Precision accuracy grade with strictly controlled rotational runout for precision machine tool spindles.

W33: One circumferential lubrication groove plus evenly distributed through holes on outer ring, enabling continuous lubricant replenishment during machine operation.

Load & Speed Data

Basic dynamic load rating Cr：73.7 kN

Basic static load rating C0r：106 kN

Permissible speed, grease lubrication：9 500 r/min

Permissible speed, oil-air lubrication：11 000 r/min

Material & Additional Properties

Material: Bearing steel

Indicative carbon footprint：2.4 kg CO₂e

Net weight：0.643 kg

eClass code：23-05-09-01

UNSPSC code：31171505

Suffix Explanation

NN: Double row cylindrical roller bearing with triple-rib inner ring. Double roller rows deliver much higher radial rigidity than single row bearings of identical outer dimensions. It can bear small bidirectional axial loads, and rollers have limited axial displacement.

3012: Medium cross-section Series 30 double row bearing with high load capacity, suitable for spindle assemblies requiring superior radial stiffness.

TN: Polyamide cage, lightweight non-metallic construction with low friction coefficient for continuous medium-high speed operation under stable temperature.

SP: Precision accuracy grade. Dimensional tolerance, radial and axial runout are tighter than standard bearings to guarantee machining precision.

C1 clearance: Minimal radial internal clearance, commonly adopted in preloaded precision spindle systems to suppress high-speed vibration.

W33: Circumferential groove and penetrating oil holes on outer diameter. Grease or oil can be fed through housing oil channels directly into rolling contact zones for on-line re-lubrication during long production runs.

Important reminder: This straight bore NN-type double row cylindrical roller bearing has roller axial restriction; no large axial floating capacity. It withstands slight bidirectional axial loads, while heavy axial loads require matched angular contact ball bearings. Align W33 oil holes precisely with housing oil passages during assembly to avoid blockage. C1 minimal clearance is sensitive to interference fit and operating temperature; excessive preload causes raceway overheating and damage. Open bearing without built-in seals; labyrinth seals or oil seals must be installed on housings to block coolant and dust ingress. No pre-filled grease upon delivery; continuous lubrication relies on external supply system working together with W33 groove. Never strike inner or outer ring directly during assembly to prevent indentations on raceways and rollers.

Alternative variants:

NN3012 TN/SP (straight bore, without W33 lubrication groove, no on-line re-lubrication)

NN3012 KTN/SPW33 (1:12 tapered bore, TN cage, SP grade, W33 feature, adjustable preload during assembly)

NN3012 TNHA/SPW33 (high-temperature polyamide cage for continuous high-temperature production)

NN3012 TN/UPW33 (UP ultra-precision grade for ultra-precision mirror machining spindles)

2 Structure & Operating Characteristics

NN 3012 TN/SPW33 is a medium-size double row precision cylindrical roller bearing, SP accuracy class with C1 minimal radial clearance, TN polyamide cage and integrated W33 outer ring lubrication structure. The double-row roller layout greatly improves radial load capacity and spindle radial rigidity compared with single row bearings of equal envelope dimensions, making it a mainstream radial support solution for precision machine tool spindles. The triple-rib inner ring limits roller axial movement and bears minor bidirectional axial forces, simplifying bearing pairing design for some spindles.

Equipped with straight cylindrical bore, positioning and preload are realized by interference fit between shaft journal and inner ring. The W33 groove and oil holes serve as a key advantage for non-stop production equipment, allowing continuous lubricant supply without shutdown. Open construction supports oil-air lubrication, circulating oil lubrication and pressure grease lubrication. Combined C1 minimal clearance and precision manufacturing tolerances reduce rotary vibration at high speed and stabilize workpiece surface finish.

Selection guide:

NN3012 TN/SPW33 (straight bore, W33 lubrication channel, SP C1 clearance, precision spindles with continuous operation and on-line re-lubrication)

NN3012 TN/SP (straight bore without lubrication groove, intermittent operation without continuous re-lubrication)

NN3012 KTN/SPW33 (1:12 tapered bore, preload adjustable during assembly)

NN3012 TNHA/SPW33 (heat-resistant cage for high ambient temperature production lines)

NN3012 TN/UPW33 (ultra-precision grade for optical and mirror finishing equipment)

Recommended matching bearing: 23412 precision double-direction thrust bearing or 7012 SP angular contact ball bearing to sustain heavy axial loads.

3 Core Performance Advantages

1. NN double roller row design delivers outstanding radial load capacity and excellent spindle rigidity, minimizing spindle deflection under cutting forces.

2. TN polyamide non-metallic cage ensures stable rotation and low friction, reducing operational noise under medium-high speed conditions.

3. W33 circumferential outer ring groove and through oil holes support continuous on-line re-lubrication, ideal for long-term non-stop production machinery.

4. SP precision standard together with C1 minimal radial clearance achieves tight control over rotational runout, mitigates high-speed vibration and stabilizes dimensional accuracy in finishing processes.

5. Triple-rib inner ring construction accepts slight bidirectional axial loads and simplifies spindle bearing configuration.

6. Bearing steel raceways and rollers maintain stable contact performance, offering sufficient load ratings to balance rigidity, load capacity and medium-high speed operation.

4 Typical Application Fields

4.1 Vertical & horizontal machining center spindle units

Finishing spindles of medium-sized machining centers running continuously, equipped with automatic grease supply systems

4.2 Cylindrical grinders, jig grinders and CNC tool grinder spindles

Precision grinding machines with strict requirements for spindle rigidity, vibration, temperature rise and surface finish quality

4.3 Precision CNC lathes and turn-mill composite machine spindles

Heavy-duty finishing cutting requiring high radial rigidity and circulating lubrication systems

4.4 Other high-end precision continuously operating rotary components

Precision rotating machinery demanding high radial rigidity, capacity for minor bidirectional axial loads and on-line lubricant replenishment

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

SP precision bearings should be assembled in constant-temperature dust-free clean workshops. Thoroughly remove contaminants on shaft journals, housing bores and spacer contact surfaces. Preload of straight bore bearings depends on interference fit; control journal tolerance accurately. Excessive interference eliminates internal clearance and leads to excessive temperature rise. Align W33 lubrication holes with housing oil passages during assembly to avoid oil channel blockage. After assembly, implement low-speed gradual speed-up no-load running-in and monitor spindle temperature and vibration continuously. Reliable sealing must be installed on machine housings to prevent coolant and dust from reaching rolling surfaces.

5.2 Selection Guidance

Long continuous production, automatic lubrication system, on-line re-lubrication required, high-rigidity precision spindle → NN3012 TN/SPW33

Intermittent machining without continuous re-lubrication demand → NN3012 TN/SP

On-site preload adjustment needed during assembly, choose tapered bore variant → NN3012 KTN/SPW33

Production line with high ambient temperature and all-day continuous operation → TNHA high-temperature cage version

Ultra-precision mirror machining requiring top-tier rotary accuracy → NN3012 TN/UPW33

Important notice: This bearing only withstands small bidirectional axial loads. Dedicated axial support bearings are mandatory under sustained heavy axial force.

5.3 Lubrication Maintenance Instruction

No lubricant pre-filled at factory. Oil-air lubrication is preferred to reach maximum permissible speed; pressure circulating grease lubrication is recommended for long-running medium-low speed production. W33 groove continuously refreshes grease inside rolling zones. Monitor bearing temperature regularly and avoid prolonged overheating. Inspect oil passage accessibility periodically; clogged holes cause localized starvation wear. Lubrication interruption quickly triggers premature damage to rollers and cage.

5.4 Environmental Application Notes

Open structure without built-in seals; labyrinth seals or oil seals on housings are compulsory. Raceways and rollers are extremely sensitive to tiny hard particles. Contamination amplifies vibration and rapidly deteriorates machining accuracy. Frequent shock loads should be avoided to prevent indentations on rolling contact surfaces. Protect W33 oil holes during assembly against metal debris blockage.

6 Fault Identification

Common failure modes: rising vibration during cutting, regular texture patterns on machined workpieces, sustained abnormal spindle temperature increase, periodic rotational noise, cage abrasion, roller end scuffing and raceway fatigue spalling. Typical problems for straight bore double row bearings include improper interference fit causing persistent overheating; W33 variants often suffer local insufficient lubrication due to blocked oil holes. Shut down equipment immediately upon persistent abnormal noise or irreversible accuracy degradation. Bearings with permanent damage to raceways, rollers or cage cannot be repaired and need complete replacement.