DKFL NA 6911 Needle Roller Bearing
The DKFL NA 6911 belongs to the category of machined needle roller bearings fitted with integral guide flanges and a separate, precision-finished inner ring. Designed for shafts with a 55 mm bore diameter, an outside diameter of 80 mm, and an extra-wide 45 mm profile, this bearing provides superior radial rigidity and high load ratings. Compared with narrower series (such as the 49 series measuring 25 mm wide in this size), the 69 series delivers substantially greater effective roller contact length, making it ideal for sustaining severe radial forces and mechanical impact loads.
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Product Detail
Needle Roller Bearing DKFL NA 6911 Machined Needle Roller Bearing with Inner Ring | 55 mm Shaft Diameter | Extra-Wide Industrial Design
Engineered for maximum radial load capacity within limited radial envelopes, the DKFL NA 6911 features a precision-ground inner ring, extended linear roller contact, and outer ring lubrication channels under DKFL engineering standards at Kamyar Gostar Iranian (KGICO).
Technical Overview of the DKFL NA 6911 Needle Roller Bearing
The DKFL NA 6911 belongs to the category of machined needle roller bearings fitted with integral guide flanges and a separate, precision-finished inner ring. Designed for shafts with a 55 mm bore diameter, an outside diameter of 80 mm, and an extra-wide 45 mm profile, this bearing provides superior radial rigidity and high load ratings. Compared with narrower series (such as the 49 series measuring 25 mm wide in this size), the 69 series delivers substantially greater effective roller contact length, making it ideal for sustaining severe radial forces and mechanical impact loads.
The integrated case-hardened and ground inner ring eliminates the requirement for direct shaft hardening and ground raceway preparation on the machine shaft. Furthermore, an integrated circumferential lubrication groove with oil feed holes on the outer ring ensures reliable, continuous delivery of lubricant to the rolling elements, greatly reducing friction and maximizing operating life under harsh industrial conditions.
Nomenclature and Designation Analysis (DKFL NA 6911)
Prefix "NA": Identifies a machined needle roller bearing with retaining flanges, supplied complete with an independent inner ring.
Dimension Series "69": Denotes the heavy-duty, extra-wide dimensional series designed to incorporate longer needle rollers for significantly elevated dynamic load carrying capabilities.
Bore Code "11": Multiplied by 5 (11 × 5 = 55 mm), designating a nominal inner ring diameter of 55 mm.
Lubrication Feature: Configured with an annular lubrication groove and radial discharge holes on the outer ring to simplify routine servicing and relubrication.
DKFL: High-precision industrial bearing brand manufactured to rigorous metallurgic standards, supplied and backed by Kamyar Gostar Iranian (KGICO).
Engineering Specifications and Dimensions
| Bore (d) | Outer Diameter (D) | Total Width (B) | Roller & Cage Assembly | Inner Ring Status | Lubrication System | Approx. Weight | Material |
|---|---|---|---|---|---|---|---|
| 55 mm | 80 mm | 45 mm | Precision needle rollers with steel cage | Included (Hardened & Ground) | Annular groove & holes in outer ring | Approx. 0.74 kg | 100Cr6 High-Carbon Chrome Steel |
Technical Comparison: NA 6911 vs. Equivalent 55 mm Shaft Options
Comparative technical analysis of needle roller bearing configurations for 55 mm shaft systems:
| Bearing Designation | Dimensions (d × D × B) | Inner Ring | Radial Load Capacity | Primary Engineering Advantage |
|---|---|---|---|---|
| NA 6911 (DKFL) | 55 × 80 × 45 mm | Included (Ground) | Maximum (45 mm Wide) | Superior load distribution and bending stiffness without requiring hardened shafts |
| NA 4911 | 55 × 80 × 25 mm | Included | Standard / Moderate | Standard width suited for narrow housing geometries |
| RNA 6911 | 63 × 80 × 45 mm | None (Without Inner Ring) | Very High | Rollers run directly on a hardened and ground 63 mm shaft to minimize radial footprint |
Key Features and Competitive Advantages of DKFL NA 6911
45 mm Extra-Wide Profile
Substantially extended contact length dissipates high localized forces across a wide raceway area, preventing premature brinelling and fatigue.
Separate Precision Inner Ring
Enables immediate mounting onto commercial unhardened shafting without costly post-machining, induction heat treatment, or shaft grinding.
Integrated Relubrication Channels
Circumferential oil groove and multiple radial lube holes ensure efficient distribution of grease or circulating oil to all rolling contact paths.
Robust Retaining Cage
Precisely guides and spaces needle rollers, mitigating roller skew and frictional spikes during rapid acceleration, stopping, and reversal cycles.
Premium 100Cr6 Chrome Steel
Engineered through vacuum degassing and precise heat treatment to 58–62 HRC, delivering exceptional wear resistance and dimensional stability.
Guaranteed DKFL Quality
Subject to strict ISO quality control for dimensional accuracy, hardness, and runout, backed by full warranty from Kamyar Gostar Iranian.
Primary Industrial Applications for the NA 6911
- Heavy Industrial Speed Reducers & Gearboxes: Shaft locations where heavy radial gear loads must be accommodated in confined radial spaces.
- Hydraulic Piston Pumps and Fluid Motors: Stiff support for 55 mm drive shafts undergoing severe cyclical pressure fluctuations.
- Textile Equipment & High-Speed Rotary Printing: Calender rolls and guide drums demanding minimum radial deflection and true-running rotation.
- Packaging Machinery & Material Conveying: High-load transfer drums and processing feed rolls requiring durable, vibration-resistant bearings.
- Mechanical Presses and Metal-Forming Tools: Shaft assemblies subject to continuous high shock loads and reversing rotary/oscillating duty.
Installation Guidelines and Engineering Instructions
When pressing the outer ring into the housing bore, verify that the outer ring lubrication holes align squarely with the housing grease fitting or oil duct to prevent blocking lubricant flow paths.
The NA 6911 needle roller bearing is engineered strictly for pure radial loads. The machined integral retaining flanges guide the rollers only and cannot withstand axial thrust. In applications with axial loads, pairing with dedicated thrust bearings is required.
Independent Ring Assembly Practice
The separable inner ring can be mounted independently onto the 55 mm shaft using an induction heater or mechanical fitting tool. The outer ring with cage and rollers is pressed square into the housing. When mating the shaft assembly into the housing, use a gentle rotary motion to prevent roller scoring on the finished inner raceway.
Frequently Asked Questions (FAQ)
1. What is the fundamental difference between NA 6911 and RNA 6911?
The NA 6911 comes complete with an independent, precision-ground inner ring designed for a standard 55 mm shaft. The RNA 6911 is supplied without an inner ring; its rollers run directly on a 63 mm hardened (58–64 HRC) and ground shaft, minimizing the overall radial assembly height.
2. Why select the NA 6911 instead of the NA 4911?
The 69 series provides a 45 mm total width compared to 25 mm for the 49 series. This extra width nearly doubles the contact length of the needle rollers, providing significantly higher static and dynamic radial load ratings for heavy-duty drives.
3. Which lubricant is recommended for the DKFL NA 6911?
For standard industrial operating speeds and heavy loads, a high-quality lithium-complex grease with extreme pressure additives (EP2) is ideal. In high-speed, high-temperature, or continuous-duty gear units, circulating oil or an oil bath system should be used.
Inquire and Purchase DKFL NA 6911 Needle Roller Bearings
Contact the engineering and sales team at Kamyar Gostar Iranian (KGICO) for real-time inventory checks, bulk pricing, 2D/3D CAD drawings, and application engineering support.
Check Stock & Place Order at kgico.co