1 Model Information & Technical Parameters

Model：NN 3005 K/SP

Dimensions

Bore d：25 mm

Outer diameter D：47 mm

Width B：16 mm

Bore type: 1:12 tapered bore

Code Explanation

NN: Double row cylindrical roller bearing, inner ring double ribs, outer ring ribless

3005: Size series 30, size code 05 (nominal bore 25 mm)

K: 1:12 tapered bore, enables preload adjustment via lock nut

SP: Super precision tolerance class for high-end spindle applications

Load Characteristics

Permitted load: Radial load only; axial load capacity negligible

Structure: Separable design, inner ring with two ribs, outer ring free; solid brass cage guiding rollers

Limiting speed: Depends on lubrication; oil-air lubrication achieves far higher speed than grease lubrication

Pre-grease: No pre-filled grease from factory; lubricant to be added upon installation

Logistics & Industry Codes

Net weight：0.13 kg

Indicative carbon footprint：0.21 kg CO₂e

eClass code：23-05-09-01

UNSPSC code：31171505

Suffix Explanation

NN: Double row cylindrical roller bearing without outer ring ribs. Inner and outer rings are separable for easy assembly and maintenance.

K: 1:12 tapered bore. Axial pushing expands inner ring radially to apply bearing preload, classic solution for machine tool spindles.

SP: Super precision spindle grade. Superior dimensional and rotational accuracy compared to standard P4 for precision machining and grinding spindles.

Important reminder: The outer ring has no ribs and cannot sustain axial force independently. Spindle layout must adopt paired angular contact ball bearings to carry axial load. Excessive preload during tapered bore assembly causes overheating, seizure and premature fatigue failure. SP precision bearings must not be installed by hammer impact; thermal mounting or hydraulic nut assembly is recommended. Grease lubrication suits medium-low speed; oil-air lubrication preferred for high-speed spindles. Straight bore equivalent: NN3005/SP. Higher precision option: UP grade; general precision alternative: NN3005K/P4.

2 Structure & Operating Characteristics

NN 3005 K/SP super precision double row cylindrical roller bearing features two parallel roller rows delivering outstanding radial rigidity. The 1:12 tapered bore allows accurate on-site preload adjustment to match varying rotating speed and cutting load. SP ultra-precision machining minimizes form errors of raceways and rollers to guarantee low rotational runout for high-precision machining. Separable inner and outer rings simplify disassembly and maintenance of spindle assemblies.

Selection reference:

NN3005 K/SP (taper bore + SP super precision, adjustable preload for precision machine spindles)

NN3005 /SP (straight cylindrical bore, no taper preload capability)

NN3005 K/P4 (taper bore P4 precision, cost effective for general precision machinery)

NN3005 K/UP (taper bore UP ultra-precision for ultra-precise grinders and coordinate equipment)

N/NF/NJ series: Single row cylindrical roller bearings with lower radial stiffness than NN type

7005 series angular contact ball bearings: Matched set to undertake spindle axial loads.

3 Core Performance Advantages

1. Double roller row design offers high radial load capacity and exceptional radial rigidity to suppress spindle radial deflection.

2. 1:12 tapered bore (K) enables precise preload tuning during assembly for wide speed range applications.

3. SP super precision grade delivers minimal rotational runout, meeting requirements for finishing and grinding processes.

4. Separable inner and outer rings simplify component disassembly, replacement and spindle maintenance.

5. Capable of relatively high operating speeds under appropriate lubrication for medium & high-speed precision spindle systems.

4 Typical Application Fields

4.1 Precision Machine Tool Spindle Units

CNC lathe spindles, vertical machining center spindles, internal & external cylindrical grinder high-speed spindles, jig grinder spindles

4.2 High-Accuracy Precision Rotary Equipment

Rotary supports for precision test fixtures, precision gear grinding machines, high-speed precision dividing heads

4.3 High-speed rotary mechanisms requiring adjustable preload, high radial rigidity and minor axial load

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Precision bearing assembly requires clean, dust-free workshop. All mating parts shall be thoroughly cleaned free of metal chips and contaminants. Hydraulic nut is recommended for uniform axial preloading of tapered bore inner ring; hammer striking on bearing faces is prohibited. Monitor preload travel strictly; over-preload leads to sharp temperature rise. Conduct no-load temperature run-in after assembly. Shaft and housing bore geometry tolerances must comply with SP precision bearing requirements.

5.2 Selection Guidance

Precision machine spindles, adjustable preload, high rotational accuracy demand → NN3005 K/SP

Medium precision requirement, cost control priority → NN3005 K/P4

Ultra-high precision optical grinders, coordinate measuring equipment → NN3005 K/UP

Fixed fit installation without on-site preload adjustment → NN3005 /SP

Applications with significant axial load: Combine this bearing with matched pair of 7005 series precision angular contact ball bearings.

5.3 Lubrication Maintenance Instruction

No lubricant pre-filled on delivery. High-speed bearing grease for medium-low speed operation; oil-air lubrication preferred for high-speed spindles; oil bath lubrication rarely adopted. Continuously monitor bearing temperature; stable steady-state temperature rise ≤25K. Sustained temperature increase indicates improper preload or insufficient lubrication.

5.4 Environmental Application Notes

The bearing itself has no integrated seals. Spindle unit must be equipped with oil seals or labyrinth seals to block coolant and dust ingress. Do not subject the bearing to sustained or alternating axial loads. Shock loads cause permanent indentations on rollers and raceways, destroying precision.

6 Fault Identification

Common failure modes: Continuous abnormal temperature rise, increased spindle radial runout, periodic operating noise, surface indentations on raceways, roller fatigue spalling. Stop operation immediately once precision degradation or persistent abnormal noise occurs. Precision bearings with plastic deformation or raceway damage shall be fully replaced; repair and reuse are not allowed.