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R Series
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R2-5-ZZ Inch Series Miniature Ball Bearing | High-Performance Precision | 3.175×7.938×3.571mm

R2-5-ZZ Inch Series Miniature Ball Bearing | High-Performance Precision | 3.175×7.938×3.571mm

The R2-5-ZZ is a precision-engineered, inch-series miniature deep groove ball bearing designed for applications where rotational stability and radial clearance control are paramount. With a 1/8" bore diameter, this model is slightly more robust than the ultra-micro series, offering a balanced power-to-size ratio. It is equipped with dual metallic shields (ZZ) that provide a physical barrier against workplace debris while maintaining a non-contact interface with the inner ring to prevent friction-induced heat. This specialized construction ensures the R2-5-ZZ remains the preferred choice for high-speed micro-motors and sensitive transmission systems.

R2-5-ZZ Miniature Deep Groove Ball Bearing 3.175 × 7.938 × 3.571 mm | Low Vibration & High Durability

Optimized for mechanical assemblies where precision and longevity cannot be compromised, the R2-5-ZZ excels in medium-to-high RPM environments. Its internal raceway geometry is honed to a mirror finish, significantly reducing the starting torque and operational noise. Whether integrated into a high-end RC brushless motor or a medical ventilation system, this bearing delivers consistent performance under both radial and axial loads.

R2-5-ZZ Inch Series Miniature Ball Bearing | High-Performance Precision | 3.175×7.938×3.571mm

Comprehensive Applications

The R2-5-ZZ is a versatile component widely utilized by industrial designers and technicians in the following fields:

Automated Systems & Robotics
  • Collaborative Robot Joint Actuators
  • Micro-Stepper Motors
  • Precision Linear Guide Rollers
  • Industrial Pick-and-Place Sensors
Aviation & RC Hobbyist Technology
  • High-Performance Brushless Outrunner Motors
  • Remote Controlled Helicopter Tail Rotors
  • Miniature Gas Turbine Engines
  • Electronic Speed Controller (ESC) Cooling Fans
Medical & Laboratory Devices
  • Small-Scale Peristaltic Pumps
  • Automated Blood Analyzers
  • Dental Prophy Angles and Handpieces
  • Laboratory Centrifuge Rotors
Office & Digital Equipment
  • Laser Printer Fuser Rollers
  • High-Definition Plotter Carriage Guides
  • Micro-Spindle Drives for Data Storage
  • Precision Paper Feed Mechanisms

Key Performance Features

01. GCr15 High-Carbon Chrome Steel Construction

Forged from premium SAE 52100 (GCr15) chrome steel, the rings and balls exhibit superior fatigue resistance and dimensional stability. The components undergo a rigorous heat treatment process to reach an optimal HRC 60-64 hardness, ensuring that the P5 (ABEC-5) precision grade is maintained even under continuous industrial cycling.

02. Dual Metal Shielding System (ZZ)

The R2-5-ZZ utilizes a non-rubbing metallic shield configuration. This design allows the bearing to reach significantly higher speeds than sealed variants by eliminating contact friction. The shields are precisely pressed into the outer ring, creating a labyrinth path that retains the factory-fill grease while effectively blocking larger contaminants.

03. Optimized Inch-Series Geometry

With a 1/8-inch bore and 5/16-inch outer diameter, the R2-5-ZZ fits the "mid-range" of the miniature category. This sizing provides greater load-bearing capacity than smaller micro-bearings while remaining compact enough for handheld devices. Its lightweight profile minimizes the moment of inertia, facilitating rapid acceleration and deceleration.

Technical Specifications

Bearing Type Miniature Deep Groove Ball Bearing
ISO Dimension Series Inch Miniature Series
Basic Designation R2-5
Suffix Options ZZ (Double Pressed Metal Shields)
Bore Diameter (d) 1/8" (3.175 mm)
Outer Diameter (D) 5/16" (7.938 mm)
Width (B) 9/64" (3.571 mm)
Material (Races & Balls) Chrome Steel (GCr15 / SAE 52100) or Stainless Steel (AISI 440C)
Precision Class Standard / P5 Grade Available
Cage Material Pressed Steel (ribbon type) or Polyamide
Dynamic Load Rating (Cʳ) Approx. 560 N
Static Load Rating (C₀ʳ) Approx. 180 N
Limiting Speed (Grease) 50,000 RPM
Limiting Speed (Oil) 60,000 RPM
Weight (approx.) 0.60 grams

Interchange Part Numbers

Interchangeable part numbers for rapid procurement and BOM matching:

  • NMB: RI-518ZZ
  • SKF: R2-5-2Z
  • NSK: R2-5ZZ
  • NTN: R2-5ZZ
  • KOYO: R2-5 ZZ

Design & Configuration

With over 15 years of excellence in deep groove ball bearing manufacturing, Welink Bearing specializes in providing custom solutions for high-performance micro-rotational systems. The R2-5-ZZ is designed for seamless integration and extreme durability. For our industrial OEM partners, we offer specialized configuration options, including custom radial clearances (C2, CN, C3), varied grease-fill percentages, and professional-grade noise-damping lubricants to meet your specific application environment.

"Experience engineered precision with the Welink R2-5-ZZ—delivering high-speed reliability and micro-dimensional excellence for the world's most sensitive technologies.”

Download Product Catalog (PDF)

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