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6308 Bearing 40×90×23mm Deep Groove Ball Bearing | RHD

The reliable workhorse - 40mm bore of steady performance.

Meet the 6308: With 4159kg (40.8kN) of engineering excellence and 40mm 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.

40mm
Bore Diameter
90mm
Outer Diameter
23mm
Width
40.8 kN
Load Rating
4159 Kg
Load Capacity
0.639 Kg
Weight
Technical Specifications Applications 📞 Call +91-9702081858
6308 Bearing 40×90×23mm - RHD Bearings

6308 BEARING SPECIFICATIONS

Precision-engineered for reliability and performance

🔍 Common Search Terms

6308 bearing dimensions 40mm bore bearing load capacity medium bearing for motors precision bearing 40mm shaft machinery bearing 6308 bearing specifications

📏Dimensions

d - ID (Bore Diameter)
40mm
D - OD (Outer Diameter)
90mm
B - Width
23mm
d₁ - Shoulder Diameter
≈56.11mm
D₂ - Recess Diameter
≈77.7mm
r₁,₂ - Chamfer Radius
min. 1.5mm
6308 Bearing: 40 × 90 × 23mm

Bearing Cross-Sectional View

6308 Deep Groove Ball Bearing Technical Drawing

⚡Load Ratings

Dynamic Load (Cr) 40.8kN
Static Load (Cor) 24.0kN
Load Capacity (kN) 40.8kN
Load Capacity (kg) 4159kg

💡What This Means

Dynamic Load (40.8kN): Maximum force while rotating. Exceeding this causes rapid wear and failure within hours.
Static Load (24.0kN): 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 7000 RPM
Oil Lubrication 8500 RPM
RHD Z2V2 Bearings 1400 RPM
RHD Z3V3 Bearings 2880 RPM
RHD Z4V4 Bearings 6000+ RPM

💡What This Means

Grease Limit (7000 RPM): Heat generation increases exponentially above this. Grease breaks down, causing seizure.
Oil Advantage (8500 RPM): Better heat dissipation allows higher speed. Required for high-speed spindles.
Safe Operating Speed: Use 90% of limit (6300 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 6308 application worldwide

📊Vibration Classes

V2 Grade
Low: 180 μm/s
Med: 150 μm/s
High: 130 μm/s
V3 Grade
Low: 110 μm/s
Med: 90 μm/s
High: 80 μm/s
V4 Grade
Low: 82 μm/s
Med: 50 μm/s
High: 50 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 < 49 dB
Z3 Grade < 45 dB
Z4 Grade (Quiet) < 41 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) 1-11 μm
C0 (Normal) 6-20 μm
C3 (Loose) 15-33 μm
C4 (High Temp) 28-46 μm
C5 (Extra High Temp) 40-64 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

6308-ZZ

Most Popular

Double metal shields

Speed Factor: 0.9 (6750 RPM)
Protection: Dust protection
Lubrication: Sealed for life

When to Use 6308-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

6308-2RS

Protected

Double rubber seals

Speed Factor: 0.7 (5250 RPM)
Protection: Moisture and dust
Lubrication: Sealed for life

When to Use 6308-2RS

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

6308

High Speed

Open bearing, no seals

Speed Factor: 1.0 (7500 RPM)
Protection: None
Lubrication: External required

6308-Z

Balanced

Single metal shield

Speed Factor: 0.95 (7125 RPM)
Protection: Light dust protection
Lubrication: Pre-greased

6308-RS

Protected

Single rubber seal

Speed Factor: 0.8 (6000 RPM)
Protection: Moisture and dust
Lubrication: Pre-greased, sealed

APPLICATIONS

Precision performance across industries

Processing Drums

  • Concrete mixer barrels
  • Cement batch rollers
  • Food dryer drums
  • Rotary kiln oven shafts
  • Seed coating machines
  • Powder blending rotors
  • Mineral sifter drums
  • Liquor aging casks

Key Requirements: 40mm shaft with 40.80kN (≈4159kg) dynamic load, 7,000 RPM grease lubrication, 90×23mm for industrial rotating drums

Automated Lifts

  • Goods elevator drums
  • Dock leveler rollers
  • Freight hoist sheaves
  • Parking system pulleys
  • Warehouse lift chains
  • Garage lift carriages
  • Hospital bed movers
  • Theatre rigging winches

Key Requirements: Precision 40mm bore, 24.00kN (≈2447kg) static load, steady under high, static weight

Field Tools

  • Soil auger pivot shafts
  • Livestock feed mixers
  • Heavy fertilizer spreaders
  • Harrow disc axles
  • Plough head guides
  • Harvest cart axles
  • Riding mower drives
  • Field survey trolleys

Key Requirements: 40mm bore, 23mm width, for rugged, outdoor agrimechanical work

Compatible Models & Shaft Requirements

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

🔄Related Models

6808 (40×52×7mm) 6908 (40×62×12mm) 6008 (40×68×15mm) 16008 (40×68×9mm) 62208 (40×80×23mm) 6208 (40×80×18mm) 62308 (40×90×33mm)

🔧Shaft Requirements

Nominal Diameter 40.000mm
Tolerance Grade h6 (39.984-40.000mm)
Surface Finish Ra 0.8μm max
Runout Tolerance 0.015mm 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 medium 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 40mm bore (ID) with 6808, 6908, 6008, so it can be considered where the shaft is fixed at 40mm. The 6308 is rated 40.80kN dynamic / 24.00kN static at 90mm OD — the highest-capacity 40mm-bore option, above the 62208 (22.50kN).

💰Value Engineering

Best value in medium-bearing category for 40.80kN performance. Quality bearings last 3-10x longer than cheap alternatives, reducing total cost of ownership.

FREQUENTLY ASKED QUESTIONS

Expert guidance for 6308 bearing applications

Bearing Selection & Replacement ▼

What shaft tolerance is recommended for 6308 bearing installation?

h6 tolerance grade (39.987-40.000mm) provides optimal fit and performance for 6308 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 calipers, 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 6308 bearing with a different size bearing?

No, 6308 bearings have unique 40×90×23mm 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 6308 replacement or consult engineering specifications for alternative solutions.
Keep spare 6308 bearings in stock to avoid production delays and ensure consistent quality.

What load capacity does the 6308 bearing provide?

6308 bearing offers 4161.6kg (40.80kN) dynamic load capacity and 24.00kN static load capacity, suitable for motor and machinery 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 4161.6kg (40.80kN) dynamic limit with appropriate safety factors.
Use 6308 bearings for applications requiring up to 4163kg load capacity with standard safety margins.
Installation & Maintenance ▼

What lubrication is required for 6308 bearings?

6308 bearings require grease lubrication for standard applications, with 7,500 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 6308 bearing?

Install 6308 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 6308 bearings?

6308 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 6308 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 6308 bearings?

Signs of wear include increased noise, vibration, temperature rise, and reduced performance in 6308 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 6308 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 6308 bearing cost compare to alternatives?

6308 bearings offer excellent value with 4161.6kg (40.80kN) 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 6308 typically cost 20-30% more but last 3-10x longer than budget alternatives.

What performance benefits does 6308 bearing provide?

6308 bearings deliver high load capacity, excellent speed capability, precision dimensions, and reliable performance in machinery applications.
Why This Matters
Performance directly impacts system efficiency, reliability, and overall productivity.
How To Handle It
Select 6308 bearings for applications requiring 40mm bore, 4161.6kg (40.80kN) load capacity, and 7,500 RPM capability.
6308 bearings excel in applications requiring compact size with high performance capabilities.

How can I optimize 6308 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 6308 bearing service life from 20,000 to 50,000+ hours in typical applications.
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