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684 Bearing 4×9×4mm Deep Groove Ball Bearing | RHD

The 4mm precision performer - delivering exceptional accuracy and reliability in the most demanding micro-applications.

Meet the 684: With 35kg (0.35kN) of engineering excellence and 4mm precision, this bearing delivers the perfect blend of personality and performance for your critical applications. The most widely used bearing in electronics, small motors, and precision instruments.

4mm
Bore Diameter
9mm
Outer Diameter
4mm
Width
0.35 kN
Load Rating
35 Kg
Load Capacity
0.0008 Kg
Weight
Technical Specifications Applications 📞 Call +91-9702081858
684 Bearing 4×9×4mm - RHD Bearings

684 BEARING SPECIFICATIONS

Precision-engineered for reliability and performance

🔍 Common Search Terms

684 bearing dimensions 4mm bore bearing load capacity miniature bearing for precision measurement advanced optics bearing micro manufacturing bearing 4mm shaft 684 bearing specifications

📏Dimensions

d - ID (Bore Diameter)
4mm
D - OD (Outer Diameter)
9mm
B - Width
4mm
684 Bearing: 4 × 9 × 4mm

Bearing Cross-Sectional View

684 Deep Groove Ball Bearing Technical Drawing

⚡Load Ratings

Dynamic Load (Cr) 0.35kN
Static Load (Cor) 0.4kN
Load Capacity (kN) 0.35kN
Load Capacity (kg) 35kg

💡What This Means

Dynamic Load (0.35kN): Maximum force while rotating. Exceeding this causes rapid wear and failure within hours.
Static Load (0.4kN): Maximum force when stationary. Use 80% for safety.
Calculate Your Load: Measure shaft forces, belt tensions, or gear loads. Include shock/vibration factors.
Failure Warning: Overloading causes bearing raceways to crack and balls to flatten permanently.

🔄Speed Limits

Grease Lubrication 49000 RPM
Oil Lubrication 57000 RPM
RHD Z2V2 Bearings 1400 RPM
RHD Z3V3 Bearings 2880 RPM
RHD Z4V4 Bearings 6000+ RPM

💡What This Means

Grease Limit (49000 RPM): Heat generation increases exponentially above this. Grease breaks down, causing seizure.
Oil Advantage (57000 RPM): Better heat dissipation allows higher speed. Required for high-speed spindles.
Safe Operating Speed: Use 90% of limit (44100 RPM) for maximum L10 life of 10,000+ hours.
Failure Mode: Exceeding speed causes cage failure, ball skidding, and catastrophic overheating within minutes.

🔧Material & Quality

Steel Grade SAE52100
Ball Grade G10
Carbon Content 0.95-1.05%
Chromium Content 1.40-1.65%
ISO Standard 15:2011 Compliant

💡What This Means

SAE52100 Chrome Steel: Premium bearing steel - harder than tool steel
G10 Balls: Ultra-precision balls with ±0.25µm tolerance
High Carbon: Superior hardness and wear resistance
Chromium: Adds corrosion resistance and toughness
ISO Standard: Fits any 684 application worldwide

📊Vibration Classes

V2 Grade
Low: 48 μm/s
Med: 26 μm/s
High: 22 μm/s
V3 Grade
Low: 31 μm/s
Med: 16 μm/s
High: 15 μm/s
V4 Grade
Low: 28 μm/s
Med: 10 μm/s
High: 10 μm/s

💡What This Means

V2 Grade: Standard grade - good for general applications
V3 Grade: Low vibration - like a smooth car engine
V4 Grade: Ultra-smooth - for precision instruments
Frequency Bands: Measured across different rotation speeds

🔇Noise Levels

Z2 Grade < 32 dB
Z3 Grade < 28 dB
Z4 Grade (Quiet) < 24 dB
Application Precision Equipment

💡What This Means

Z2 Grade: Quiet as a library - good for most applications
Z3 Grade: Very quiet - like a whisper (40 dB = normal whisper)
Z4 Grade: Ultra-quiet - perfect for bedroom fans, medical equipment
Application: Ideal for sensitive environments

⚙️Internal Clearance

C2 (Tight) 0-7 μm
C0 (Normal) 2-13 μm
C3 (Loose) 8-23 μm
C4 (High Temp) 14-29 μm
C5 (Extra High Temp) 20-37 μm

💡What This Means

C2 (Tight): Precision applications - less play, more accurate
C0 (Normal): Standard choice - works for most applications
C3 (Loose): Better for hot environments - allows thermal expansion
C4 (Exta Loose): Hot or tight-fit setups — extra room for thermal expansion.
C5 (Max Loose): Extreme heat/tight fits or near-limit speeds — maximum expansion allowance

SEAL OPTIONS

Choose the right protection for your application

684-ZZ

Most Popular

Double metal shields

Speed Factor: 0.9 (32400 RPM)
Protection: Dust protection
Lubrication: Sealed for life

When to Use 684-ZZ

Best For: Electronics, small motors, skateboards, general machinery
Conditions: Dry environments, moderate dust, precision applications
Achieves: Excellent balance of speed and protection for most applications
Avoid When: Heavy water exposure, chemical environments, food processing

684-2RS

Protected

Double rubber seals

Speed Factor: 0.7 (25200 RPM)
Protection: Moisture and dust
Lubrication: Sealed for life

When to Use 684-2RS

Best For: Outdoor applications, appliances, automotive systems, dirty environments
Conditions: Moisture, dust, contamination, washdown areas, food processing
Achieves: Maximum protection and zero maintenance requirements
Trade-off: Lower speed limit but superior environmental protection

684

High Speed

Open bearing, no seals

Speed Factor: 1.0 (36000 RPM)
Protection: None
Lubrication: External required

684-Z

Balanced

Single metal shield

Speed Factor: 0.95 (34200 RPM)
Protection: Light dust protection
Lubrication: Pre-greased

684-RS

Protected

Single rubber seal

Speed Factor: 0.8 (28800 RPM)
Protection: Moisture and dust
Lubrication: Pre-greased, sealed

APPLICATIONS

Precision performance across industries

Ultra-Precision Measurement

  • coordinate measuring machines
  • surface profilometers
  • roundness testers
  • dimensional analyzers
  • metrology systems
  • calibration equipment
  • quality control systems
  • inspection equipment

Key Requirements: 4mm shaft with 0.35kN dynamic load capacity, 49,000 RPM grease lubrication, precision 9×4mm profile for ultra-precision measurement applications

Advanced Optics

  • adaptive optics
  • wavefront sensors
  • optical interferometers
  • laser beam steering
  • precision mirrors
  • optical alignment systems
  • optical testing systems
  • spectroscopic instruments

Key Requirements: Precision 4mm bore with 0.3mm chamfer radius, 0.40kN static load rating for stable operation, 41kg load capacity for optical accuracy

Micro-Manufacturing

  • micro-machining tools
  • precision cutting systems
  • micro-drilling equipment
  • ultra-fine grinding
  • micro-engraving tools
  • nano-fabrication systems
  • micro-assembly systems
  • precision fixtures

Key Requirements: 4mm bore fits micro-manufacturing shafts, 4mm width for compact mounting, 35kg weight for efficiency, 57,000 RPM oil lubrication capability

Compatible Models & Shaft Requirements

Find bearings with the same bore size and ensure proper shaft preparation

🔄Related Models

694 (4×11×4mm) 604 (4×12×4mm) 624 (4×13×5mm) 634 (4×16×5mm)

🔧Shaft Requirements

Nominal Diameter 4.000mm
Tolerance Grade h6 (3.992-4.000mm)
Surface Finish Ra 0.8μm max
Runout Tolerance 0.013mm max

🎯Application-Specific Options

High Temperature: C3 clearance recommended
High Speed: RHD V3 & V4 bearings recommended
Corrosive Environment: SS (Stainless Steel) bearings recommended

Professional Expertise & Standards

Technical insights from 20+ years of bearing engineering and manufacturing excellence

📋ISO Compliance

ISO 15:2011 compliant dimensions ensure interchangeability with global bearing standards and seamless replacement in existing equipment.

🔬Material Science

Gcr15 chrome steel composition optimized for small bearing applications, providing superior hardness, wear resistance, and fatigue life.

⚙️Precision Engineering

C0 clearance standard for most applications, C3 available for high-temperature use. h6 shaft tolerance recommended for optimal performance.

🔧Professional Installation

Professional installation required for maximum 50,000-hour service life. Proper tools and techniques prevent 80% of premature failures.

📊Performance Comparison

Shares the 4mm bore (ID) with 694, 604, 624, so it can be considered where the shaft is fixed at 4mm. The 684 is rated 0.35kN dynamic / 0.40kN static at 9mm OD — the most compact 4mm-bore option, below the 694 (0.95kN).

💰Value Engineering

Best value in miniature bearing category for 0.35kN performance. Quality bearings last 3-10x longer than cheap alternatives, reducing total cost of ownership.

FREQUENTLY ASKED QUESTIONS

Expert guidance for 684 bearing applications

Bearing Selection & Replacement ▼

What shaft tolerance is recommended for 684 bearing installation?

h6 tolerance grade (3.991-4.009mm) provides optimal fit and performance for 684 bearings.
Why This Matters
Proper shaft tolerance ensures correct interference fit, preventing slippage while allowing thermal expansion.
How To Handle It
Measure shaft diameter with precision micrometers, ensuring it falls within h6 tolerance range before installation.
Use h6 tolerance for standard applications, h5 for high-precision requirements, and h7 for loose fits.

Can I replace a 684 bearing with a different size bearing?

No, 684 bearings have unique 4x9x4mm dimensions and cannot be replaced with other sizes without mechanical modifications.
Why This Matters
Bearing dimensions are critical for proper fit, load distribution, and system performance.
How To Handle It
Always use exact 684 replacement or consult engineering specifications for alternative solutions.
Keep spare 684 bearings in stock to avoid production delays and ensure consistent quality.

What load capacity does the 684 bearing provide?

684 bearing offers 117.3kg (1.15kN) dynamic load capacity and 0.42kN static load capacity, suitable for ultra-precision measurement applications.
Why This Matters
Load capacity determines bearing suitability for specific applications and operating conditions.
How To Handle It
Calculate actual application loads and ensure they remain within 117.3kg (1.15kN) dynamic limit with appropriate safety factors.
Use 684 bearings for applications requiring up to 117kg load capacity with standard safety margins.
Installation & Maintenance ▼

What lubrication is required for 684 bearings?

684 bearings require grease lubrication for standard applications, with 36,000 RPM capability under proper lubrication conditions.
Why This Matters
Proper lubrication reduces friction, prevents wear, and extends bearing service life significantly.
How To Handle It
Apply high-quality bearing grease during installation and maintain regular lubrication intervals based on operating conditions.
Use lithium-based grease for general applications and synthetic grease for high-temperature or high-speed operations.

How do I properly install a 684 bearing?

Install 684 bearings using proper bearing installation tools, ensuring even pressure distribution and avoiding damage to bearing surfaces.
Why This Matters
Proper installation prevents premature failure, ensures optimal performance, and maintains dimensional accuracy.
How To Handle It
Use bearing heaters for interference fits, apply force evenly, and verify proper seating after installation.
Professional installation tools prevent 80% of premature bearing failures and ensure maximum service life.

What maintenance schedule is recommended for 684 bearings?

684 bearings require regular inspection every 3-6 months, with lubrication replenishment based on operating hours and conditions.
Why This Matters
Regular maintenance prevents unexpected failures, maintains performance, and extends bearing lifespan.
How To Handle It
Establish maintenance schedules based on operating conditions, document all maintenance activities, and monitor bearing condition regularly.
Implement predictive maintenance using vibration analysis to detect issues before they cause failures.
Troubleshooting & Problem Solving ▼

What causes premature failure in 684 bearings?

Common causes include improper installation, inadequate lubrication, contamination, excessive loads, and misalignment.
Why This Matters
Understanding failure causes helps prevent future issues and improves system reliability.
How To Handle It
Implement proper installation procedures, maintain clean environments, ensure adequate lubrication, and monitor operating conditions.
80% of premature failures are preventable through proper installation and maintenance practices.

How do I identify bearing wear in 684 bearings?

Signs of wear include increased noise, vibration, temperature rise, and reduced performance in 684 bearings.
Why This Matters
Early detection of wear prevents catastrophic failures and allows for planned replacement.
How To Handle It
Monitor bearing condition regularly, use vibration analysis equipment, and establish baseline performance measurements.
Implement condition monitoring systems to detect wear patterns before they affect system performance.

What should I do if a 684 bearing fails unexpectedly?

Immediately stop operation, inspect for damage, identify root cause, and replace with properly installed new bearing.
Why This Matters
Quick response prevents secondary damage and minimizes production downtime.
How To Handle It
Document failure details, analyze root causes, implement corrective actions, and maintain spare bearings for critical applications.
Keep detailed failure records to identify patterns and prevent similar issues in the future.
Cost & Performance Optimization ▼

How does 684 bearing cost compare to alternatives?

684 bearings offer excellent value with 117.3kg (1.15kN) load capacity at competitive pricing, providing 3-10x longer lifespan than budget alternatives.
Why This Matters
Total cost of ownership includes initial cost, maintenance, replacement frequency, and downtime costs.
How To Handle It
Calculate total cost of ownership, consider quality vs. price trade-offs, and invest in proper installation and maintenance.
High-quality bearings like 684 typically cost 20-30% more but last 3-10x longer than budget alternatives.

What performance benefits does 684 bearing provide?

684 bearings deliver high load capacity, excellent speed capability, precision dimensions, and reliable performance in measurement applications.
Why This Matters
Performance directly impacts system efficiency, reliability, and overall productivity.
How To Handle It
Select 684 bearings for applications requiring 4mm bore, 117.3kg (1.15kN) load capacity, and 36,000 RPM capability.
684 bearings excel in applications requiring ultra-precision measurement performance with substantial load handling.

How can I optimize 684 bearing performance?

Optimize performance through proper installation, adequate lubrication, contamination control, and regular maintenance practices.
Why This Matters
Optimized performance extends bearing life, reduces maintenance costs, and improves system reliability.
How To Handle It
Follow manufacturer recommendations, implement preventive maintenance, monitor operating conditions, and use quality lubricants.
Proper optimization can extend 684 bearing service life from 20,000 to 50,000+ hours in typical applications.
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