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R Series
Home Deep Groove Ball Bearings R Series

R1-4 Open Deep Groove Ball Bearing | Zero-Drag Micro Rotation | 3.175×6.35×2.381 mm

R1-4 Open Deep Groove Ball Bearing | Zero-Drag Micro Rotation | 3.175×6.35×2.381 mm

The R1-4 Open is a sub-miniature imperial ball bearing designed for applications where even the slightest mechanical resistance must be eliminated. By omitting shields and seals, this "Open" configuration offers the lowest possible starting and running torque. It is specifically engineered for high-speed, light-load mechanisms housed in clean-room environments or enclosed systems where external lubrication is provided. With a 1/8-inch bore, the R1-4 Open allows for effortless free-spinning, making it a critical component for high-frequency oscillators and sensitive measuring instruments.

R1-4 Miniature Deep Groove Ball Bearing 3.175×6.35×2.381 mm | R Series – Maximum Velocity & Minimal Torque

Engineered for rotational freedom, the R1-4 Open excels in precision assemblies that require rapid acceleration and high-velocity stability. Without the drag of protective closures, this bearing dissipates heat more effectively and allows for direct visual inspection of the raceways. Whether utilized in a high-speed micro-motor or a specialized laboratory device, the R1-4 Open provides a frictionless interface that maximizes power efficiency and ensures whisper-quiet operation during continuous, high-RPM cycles.

R1-4 Open Deep Groove Ball Bearing | Zero-Drag Micro Rotation | 3.175×6.35×2.381 mm

Comprehensive Applications

Perfectly suited for technical designers and engineers focusing on zero-friction performance in 1/8-inch shaft micro-assemblies:

Scientific & Medical Instrumentation
  • High-Speed Micro-Centrifuges
  • Laser Scanning and Mirror Positioning
  • Cryogenic Cooling Pump Components
  • Optical Dial Indicators
Micro-Electronics & Computing
  • Ultra-High Speed CPU Cooling Fans
  • Small-Scale Robotics Actuators
  • Precision Rotary Encoders
  • Magnetic Storage Spindles
Aerospace & Defense
  • Miniature Gyroscopic Stabilizers
  • High-Sensitivity Anemometers
  • Compact Drone Gimbal Motors
  • Telemetry Equipment Pivot Points

Key Performance Features

01. Frictionless Open Architecture

The defining feature of the R1-4 Open is its lack of physical barriers. With no metal shields or rubber seals touching the inner ring, the bearing experiences zero "windage" or contact friction. This allows the assembly to reach significantly higher speeds compared to shielded counterparts, making it the premier choice for low-torque, high-speed micro-engineering.

02. Precision GCr15 Chrome Steel

Forged from premium-grade GCr15 Chrome Steel (SAE 52100), the races and rolling elements are finished to P5-level precision. The high-carbon steel is heat-treated to ensure maximum hardness and wear resistance, allowing the bearing to maintain its structural integrity and rotational accuracy even during extreme rotational frequencies.

03. Ultra-Slim Imperial Profile

Featuring a 3.175 mm (1/8") bore and a 6.35 mm (1/4") outer diameter, the R1-4 Open follows standard imperial sizing for seamless integration into 1/8-inch shaft systems. Its slim 2.381 mm width makes it one of the most compact bearings in the R-series, perfect for ultra-thin housings where every millimeter of space is critical.

Technical Specifications

Bearing Type Single Row Deep Groove Ball Bearing
ISO Dimension Series R Series (Miniature Imperial / Inch)
Basic Designation R1-4 (R1.4)
Suffix Options Open (No Shields / No Seals)
Bore Diameter (d) 3.175 mm (1/8")
Outer Diameter (D) 6.35 mm (1/4")
Width (B) 2.381 mm (3/32")
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) 0.283 kN (283 N)
Static Load Rating (C₀ʳ) 0.095 kN (95 N)
Limiting Speed (Grease) 56,000 r/min
Limiting Speed (Oil) 67,000 r/min
Weight (approx.) 0.00032 kg (0.32 grams)

Interchange Part Numbers

Global equivalents for streamlined procurement:

  • NMB: RI-418
  • SKF: R1-4
  • NSK: R1-4
  • NTN: R1-4
  • Barden: R1-4
  • KOYO: R1-4

Design & Configuration

For over 15 years, Welink Bearing has specialized in matching high-precision rotational hardware to complex industrial needs. The R1-4 Open provides the baseline for ultra-low torque requirements. We offer specialized customization for bulk orders, including delivery in "dry" condition (with rust-preventative oil only) or pre-lubricated with high-speed instrument oils tailored to your specific RPM and temperature parameters.

"Achieve maximum velocity with the R1-4 Open bearing—delivering zero-friction rotation, imperial precision, and unhindered performance for your high-speed micro-designs.”

Download Product Catalog (PDF)

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