Roller Bearings
Needle Roller Bearings
BOM manufactures needle roller bearings across the full range of standard configurations — drawn cup (HK/BK), cage assembly (K), solid ring (NA/NK), without inner ring (RNA), and thrust (AXK). Needle rollers carry high radial loads in a cross-section significantly smaller than conventional roller bearings at the same bore size, making them the standard choice for space-constrained, load-dense applications in CNC machinery, robotics, and industrial automation. Full-specification custom manufacturing is available, including non-standard dimensions, special materials, and integrated bearing-plus-housing assemblies.
Key Features
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Drawn Cup (HK / BK): Most compact radial envelope; HK open-end for lubrication access, BK closed-end for sealed environments
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Cage Assembly (K): Rollers guided by precision cage, mounted directly on hardened shaft without inner ring for maximum load density
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Solid Ring (NA / NK): Machined outer ring for maximum load capacity and rigidity under heavy shock; NA with inner ring, NK direct-on-shaft
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Without Inner Ring (RNA): Minimum radial envelope, rollers run directly on hardened shaft surface
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Thrust (AXK): Pure axial load capacity with minimal stack height for compact thrust support
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Full-Specification Custom Manufacturing Available
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Description
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Needle Roller Bearings
High Load, Compact Envelope Customizable
Needle roller bearings carry high radial loads in a cross-section significantly smaller than conventional roller bearings at the same bore size. The long, thin rollers maximize the contact area within a minimal radial envelope, making them the standard solution for space-constrained, load-dense applications. BOM manufactures the full range of needle roller bearing configurations to match different mounting, sealing, and load direction requirements.
- Drawn Cup (HK / BK): Most compact radial cross-section. HK (open end) for lubrication access through the bore; BK (closed end) for sealed, contamination-resistant environments
- Cage Assembly (K): Needle rollers guided by a precision cage, mounted directly on hardened shaft without inner ring. Minimum possible bore envelope and highest load density per unit diameter
- Solid Ring (NA / NK): Machined outer ring construction for maximum load capacity and rigidity under heavy shock and sustained loading. NA includes inner ring; NK mounts directly on shaft
- Without Inner Ring (RNA): Rollers run directly on hardened shaft surface, achieving the absolute minimum radial envelope for high-load applications
- Thrust (AXK): Pure axial load capacity with minimal stack height, for compact designs requiring high thrust support with low friction
- Customization: Full-specification custom manufacturing available, dimensions, materials, coatings, and bearing structure
Custom & Integrated Needle Roller Bearing Solutions
Integrated Assemblies Engineering Support
BOM manufactures full-specification custom needle roller bearing solutions for applications where catalog products do not meet the design requirement, from modified internal geometry through to complete bearing-plus-housing integrated assemblies.
- Integrated Assemblies: Complete bearing-plus-housing units, sealed sub-assemblies, and multi-element stacks engineered for direct retrofit into existing machinery
- One-Piece Machining Advantage: Inner ring, outer ring, and mating geometry machined in a single setup, eliminating stack-up tolerances and delivering tighter combined runout than separately sourced components
- Alternative Materials: Rolling elements, rings, and cage materials selected to match the operating environment, whether the requirement is corrosion resistance, high-temperature stability, or extended fatigue life under aggressive conditions
- Surface Treatment: Application-specific coatings and surface treatments engineered to extend bearing life in environments where standard finishes are insufficient
- Customization: Full-specification custom manufacturing available, dimensions, materials, coatings, and bearing structure
Needle Roller Bearings: Dimensions & Load Ratings
HK · BK · NA · NK · RNA · AXK series | Boundary dimensions per ISO 3245 / ISO 1206 | Contact us for sizes not listed
| Designation |
d mm |
D mm |
C mm |
Cr kN |
C0r kN |
|---|
Applications
CNC & Machine Tools
Spindle drive systems, precision turrets, and multi-axis positioning requiring high radial stiffness and repeatable accuracy in compact cross-sections.
Printing & Packaging Machinery
Paper feed systems, registration rollers, cutting heads, and fold-knife mechanisms requiring compact, load-dense bearings with reliable positioning.
Gearboxes & Power Transmission
Planetary gear sets, rocker arm pivots, and transmission internals where needle roller bearings provide high load capacity within tight radial envelopes.
Robotics & Servo Drives
Joint assemblies, gear reducer input/output stages, and articulated arm joints requiring minimal backlash, high stiffness, and compact space utilization.
About BOM Bearing
BOM Bearing is a professional manufacturer of needle roller bearings, delivering precision-engineered solutions for demanding industrial applications where radial load capacity, compact envelope, and repeatable performance are critical.
- Quality Assurance: ISO 9001, IATF 16949, and ISO 14001 certified; quality and environmental standards validated at every production stage
- Wide Product Range: HK, BK, K, NA, NK, RNA, and AXK series covering drawn cup, solid ring, cage assembly, and thrust configurations for all needle roller bearing applications
- Custom Manufacturing: Full-specification customization from non-standard dimensions and alternative materials to specialized coatings and complete bearing architecture redesign, engineered to your exact requirement
- Technical Support: Engineering team available for bearing selection, shaft design optimization, lubrication strategy, and application troubleshooting
- Fast Delivery: Efficient production lines and global logistics network ensuring timely delivery for both standard and custom orders
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Frequently Asked Questions (FAQ)
How do I choose between drawn cup, solid ring, and cage assembly needle roller bearings?
The choice depends on the application priority. Drawn cup (HK/BK) offers the most compact radial cross-section and is the standard choice when installation space is the primary constraint. Solid ring (NA/NK) has a machined outer ring that provides higher load capacity and greater rigidity under shock and heavy sustained loads. Cage assembly (K) eliminates the inner ring entirely for the smallest possible bore envelope. BOM engineering can recommend the optimal type based on your load, space, and mounting requirements.
What is the difference between HK and BK series?
HK series features an open end design for applications where lubrication is supplied through the bearing bore. BK series provides a closed end, offering superior sealing against external contamination and lubricant retention. Both deliver identical load capacity in the same bore and OD envelope. Choose HK for standard applications with controlled lubrication; choose BK for sealed or contaminated environments.
What are the shaft requirements for needle roller bearings without an inner ring?
K series (cage assemblies) and RNA/NK series bearings run directly on the shaft surface, which functions as the inner raceway. The shaft must be hardened and ground to the correct surface finish to support the needle rollers and achieve full rated load capacity and service life.
What lubrication is recommended for needle roller bearings?
Lubrication selection depends on the operating conditions. Oil lubrication is generally preferred for high-speed and lightly loaded applications because it generates less heat. Grease lubrication is preferred for lower-speed, higher-load applications and sealed environments where re-lubrication intervals need to be extended. BOM engineering can recommend the optimal lubricant type and quantity for your specific application conditions.
Can BOM manufacture custom needle roller bearings?
Yes. BOM manufactures full-specification custom needle roller bearings covering the complete range of customization: non-standard dimensions, alternative materials, application-specific surface treatments, custom cage geometries, and integrated assembly designs where the bearing and mating components are manufactured as a single precision unit. The engineering team supports application review, bearing selection, and design optimization.
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