1 Model Information & Technical Parameters

Model：NN 3015 KTN/UP

Dimensions

Bore d：75 mm

Outer diameter D：115 mm

Width B：30 mm

Bore type: 1:12 tapered bore

Radial clearance: C1 minimal internal clearance

Accuracy class: UP ultra-precision grade

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

Outer ring flange: None

Lubrication groove: No circumferential groove or oil holes on outer ring, no on-line re-lubrication during operation

Seal: Open design, no seals

Surface coating: Uncoated

Pre-lubrication: No lubricant supplied from factory

Code Explanation

NN: Double row cylindrical roller bearing, three ribs on inner ring, ribless outer ring with axial floating capacity to compensate spindle thermal elongation, mainly for radial loads with excellent rigidity.

3015: Size series 30 wide cross-section spindle bearing with high load capacity.

K: 1:12 tapered bore, preload adjustable by axial pushing via lock nut.

TN: Standard non-metallic roller-guided cage, stable performance.

UP: Ultra-precision accuracy grade, rotational runout tighter than SP grade, for mirror grinding and ultra-precision finishing spindles.

Load & Speed Data

Basic dynamic load rating Cr：96.8 kN

Basic static load rating C0r：150 kN

Permissible speed, grease lubrication：7 500 r/min

Permissible speed, oil-air lubrication：8 500 r/min

Material & Additional Properties

Rolling element material: Bearing steel

Indicative carbon footprint：4.0 kg CO₂e

Net weight：1.07 kg

eClass code：23-05-09-01

UNSPSC code：31171505

Suffix Explanation

NN: Double row cylindrical roller bearing. Three ribs on inner ring guide two roller rows; ribless outer ring floats axially to absorb thermal expansion, designed primarily for radial loads.

3015: Series 30 wide-section spindle bearing with extended contact length, excellent performance under heavy loads.

K: 1:12 tapered bore. Operators can adjust spindle preload on site by pushing the bearing axially with lock nut.

TN: Standard non-metallic roller-guided cage with mature and stable structure.

UP: Ultra-precision accuracy grade. Stricter tolerances on dimension, radial and axial runout than SP bearings for mirror surface and ultra-precision machining.

C1 clearance: Minimal radial internal clearance, suitable for lightly preloaded medium-high speed heavy-duty spindles to suppress vibration and achieve superior surface finish.

No W33: No circumferential lubrication groove and oil holes on outer ring. Re-lubrication can only be carried out during machine shutdown; continuous online lubrication during operation is unavailable.

Important reminder: This 1:12 tapered bore NN-type double row cylindrical roller bearing supports on-site preload adjustment. Without W33 lubrication structure on outer ring, it is not suitable for 24/7 mass production and centralized online lubrication. NN floating outer ring only bears radial loads and cannot sustain axial force; paired angular contact ball bearings are required for spindle axial positioning. Open bearing without built-in seals; high-performance labyrinth seals or oil seals must be installed on housings to block coolant and dust. No pre-filled grease upon delivery. Ideal for ultra-precision spindle equipment with intermittent production, scheduled offline maintenance and pursuit of ultimate rotary accuracy.

Alternative variants:

NN3015 KTN/SPW33 (1:12 tapered bore, SP grade, outer ring W33 groove, supports continuous production online re-lubrication)

NN3015 KTN/SP (1:12 tapered bore, SP grade, no lubrication groove, standard precision intermittent spindles)

NN3015 KTN/UPW33 (1:12 tapered bore, UP ultra-precision grade, outer ring W33 groove, ultra-precision continuous machining spindles)

NN3015 TN/UP (straight bore, UP grade, no lubrication groove, fixed preload without field adjustment)

2 Structure & Operating Characteristics

NN 3015 KTN/UP is an UP ultra-precision grade double row cylindrical roller bearing with C1 minimal radial clearance, standard TN non-metallic cage, bearing steel rolling elements and 1:12 tapered bore. No lubrication grooves or oil holes are machined on outer ring. Two rows of steel rollers share loads simultaneously to boost radial rigidity. The NN ribless outer ring slides freely in axial direction to compensate spindle thermal expansion and eliminate extra axial stress caused by temperature rise.

Core advantages are adjustable preload via 1:12 tapered bore matched with UP ultra-precision manufacturing standard. Operators can adjust preload axially using lock nut according to ultra-precision machining requirements. UP grade delivers better rotational runout control than SP specification, suppressing micro-vibration to realize mirror finishing. Mature standard TN cage delivers stable operation. Without W33 oil supply channels, lubricant can only be refilled during shutdown maintenance. It fits intermittent high-precision machining scenarios rather than all-day continuous mass production.

Selection guide:

NN3015 KTN/UP (1:12 tapered bore, TN cage, UP ultra-precision, no lubrication groove, intermittent high-precision machining, offline re-greasing, adjustable preload)

NN3015 KTN/UPW33 (1:12 tapered bore, TN cage, UP ultra-precision, W33 groove, ultra-precision continuous mass production spindles)

NN3015 KTN/SP (1:12 tapered bore, SP precision grade, no lubrication groove, standard precision machining conditions)

Recommended matching bearing: Paired 7015 UP angular contact ball bearings to bear all axial loads and realize bidirectional spindle axial positioning.

3 Core Performance Advantages

1. Double-row bearing steel roller arrangement delivers powerful radial load capacity and superior spindle rigidity, suitable for medium-speed high-precision cutting and mirror grinding.

2. NN-type wide-section double-row structure achieves uniform load distribution and better anti-tilting performance than single row cylindrical roller bearings.

3. 1:12 tapered bore enables preload adjustment via lock nut, spindle rigidity can be flexibly modified when production process changes.

4. Mature TN non-metallic cage ensures stable and reliable operation.

5. UP ultra-precision standard combined with C1 minimal radial clearance realizes stricter rotary runout control, restrains micro-vibration and guarantees mirror surface finishing quality.

6. Axially floating outer ring automatically compensates spindle thermal elongation, prevents extra internal bearing stress and extends service life.

7. Intact outer ring surface without lubrication grooves simplifies housing machining, suitable for compact small-sized ultra-precision spindle units.

4 Typical Application Fields

4.1 Spindles of ultra-precision CNC cylindrical & internal mirror grinding machines

Intermittent high-precision processing, scheduled offline maintenance, demanding ultimate workpiece surface roughness

4.2 Special spindle units for optical components and precision mold machining

Extremely strict requirements for rotary accuracy, non-24-hour continuous production mode

4.3 Precision testing spindles for laboratories & ultra-precision CNC lathe spindles

Small batch single-piece high-precision finishing with periodic shutdown maintenance and re-greasing

4.4 High-precision rotary spindles for small precision grinding equipment and tool grinders

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

UP ultra-precision bearings must be assembled in constant-temperature dust-free clean workshops with controlled temperature fluctuation. Thoroughly clean contaminants on shaft journals, housing bores and spacer contact surfaces. For the 1:12 tapered bore, adjust preload by slow and uniform axial pushing with lock nut; violent hammering is forbidden. No extra oil passages need to be reserved inside bearing housings. High-performance sealing must be installed on machine housings to block coolant and dust ingress. This NN-type bearing cannot withstand axial loads; paired UP grade angular contact bearings are mandatory for spindle axial positioning. Avoid long-term continuous shock loads.

5.2 Selection Guidance

Intermittent production, adjustable preload, ultra-high rotary accuracy, offline re-greasing → NN3015 KTN/UP

Ultra-high precision, 24-hour continuous production required, centralized online lubrication → NN3015 KTN/UPW33

Intermittent production, standard precision grade, cost-sensitive → NN3015 KTN/SP

Ultra-high precision, stable process without preload adjustment → NN3015 TN/UP

Important notice: No W33 lubrication groove on outer ring. Forced external oil supply during machine running is prohibited, which may lead to lubricant accumulation and temperature rise. NN double row structure is designed for radial loads only. Sustained axial force leads to edge stress concentration, roller scuffing and premature fatigue spalling.

5.3 Lubrication Maintenance Instruction

No lubricant pre-filled at factory. Grease lubrication or oil-air lubrication is acceptable, yet all lubricant refilling operations must be performed when equipment stops. Adopt high-quality long-life high-speed grease and strictly follow maintenance intervals to prevent accuracy degradation caused by insufficient lubrication. Continuously track bearing temperature and workpiece surface quality; inspect preload setting and lubrication condition once chatter marks occur.

5.4 Environmental Application Notes

Open structure without built-in seals; high-performance labyrinth seals or oil seals on bearing housings are compulsory. Rolling contact surfaces are extremely sensitive to hard particles; foreign contaminants easily cause raceway pitting and directly damage UP ultra-precision accuracy. TN cage fits regular continuous medium-speed working conditions; extreme high temperature accelerating cage aging should be avoided.

6 Fault Identification

Common failure modes: subtle periodic texture patterns on workpieces, continuous decline of mirror surface finishing quality, abnormal steady temperature rise of spindle, periodic rotational noise, roller scuffing, raceway fatigue spalling. Typical failures for tapered bore bearings: excessive preload leading to persistent overheating; insufficient preload resulting in reduced spindle rigidity and machining chatter marks; grease drying caused by overlong maintenance intervals; uneven abrasion of two roller rows induced by unexpected axial loads. Shut down equipment immediately upon continuous accuracy degradation or abnormal noise. Bearings with permanent damage to raceways, rolling elements or cage cannot be repaired and need complete replacement.