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6918 Bearing 90×125×18mm - RHD Bearings

Ninety millimeter bore that's got the power and the precision to handle whatever you throw at it.

Meet the 6918: With 3343kg (32.8kN) of engineering excellence and 90mm 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.

90mm
Bore Diameter
125mm
Outer Diameter
18mm
Width
32.8 kN
Load Rating
3343 Kg
Load Capacity
0.533 Kg
Weight
Technical Specifications Applications 📞 Call +91-9702081858
6918 Bearing 90×125×18mm - RHD Bearings

6918 BEARING SPECIFICATIONS

Precision-engineered for reliability and performance

🔍 Common Search Terms

6918 bearing specifications 90x115x13 bearing dimensions 6918 bearing load rating 6918 bearing speed limit 6918 bearing price 6918 bearing cross reference

📏Dimensions

d - ID (Bore Diameter)
90mm
D - OD (Outer Diameter)
125mm
B - Width
18mm
d₁ - Shoulder Diameter
≈113.7mm
D₂ - Recess Diameter
≈N/Amm
r₁,₂ - Chamfer Radius
min. 1.1mm
6918 Bearing: 90 × 125 × 18mm

Cross-Sectional View

6918 Bearing Cross-Sectional View

⚡Load Ratings

Dynamic Load (Cr) 32.8kN
Static Load (Cor) 31.5kN
Load Capacity (kN) 32.8kN
Load Capacity (kg) 3343kg

💡What This Means

Dynamic Load (32.8kN): Maximum force while rotating. Exceeding this causes rapid wear and failure within hours.
Static Load (31.5kN): 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 2000 RPM
Oil Lubrication 3400 RPM
RHD Z2V2 Bearings 1400 RPM
RHD Z3V3 Bearings 2880 RPM
RHD Z4V4 Bearings 6000+ RPM

💡What This Means

Grease Limit (2000 RPM): Heat generation increases exponentially above this. Grease breaks down, causing seizure.
Oil Advantage (3400 RPM): Better heat dissipation allows higher speed. Required for high-speed spindles.
Safe Operating Speed: Use 90% of limit (1800 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 6918 application worldwide

📊Vibration Classes

V2 Grade
Low: 210 μm/s
Med: 180 μm/s
High: 270 μm/s
V3 Grade
Low: 145 μm/s
Med: 125 μm/s
High: 180 μm/s
V4 Grade
Low: 75 μm/s
Med: 75 μm/s
High: 115 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 < 52 dB
Z3 Grade < 47 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) 1-18 μm
C0 (Normal) 12-36 μm
C3 (Loose) 30-58 μm
C4 (High Temp) 53-84 μm
C5 (Extra High Temp) 75-120 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

6918-ZZ

Most Popular

Double metal shields

Speed Factor: 0.9 (1800 RPM)
Protection: Dust protection
Lubrication: Sealed for life

When to Use 6918-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

6918-2RS

Protected

Double rubber seals

Speed Factor: 0.7 (1400 RPM)
Protection: Moisture and dust
Lubrication: Sealed for life

When to Use 6918-2RS

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

6918

High Speed

Open bearing, no seals

Speed Factor: 1.0 (2000 RPM)
Protection: None
Lubrication: External required

6918-Z

Balanced

Single metal shield

Speed Factor: 0.95 (1900 RPM)
Protection: Light dust protection
Lubrication: Pre-greased

6918-RS

Protected

Single rubber seal

Speed Factor: 0.8 (1600 RPM)
Protection: Moisture and dust
Lubrication: Pre-greased, sealed

APPLICATIONS

Precision performance across industries

Power Transmission

  • Industrial gearbox shafts
  • Wind turbine shafts
  • Elevator drive shafts
  • Mining haul truck shafts
  • Steel mill conveyor shafts
  • Bulk material machinery
  • Hydraulic system shafts
  • Construction equipment drives

Key Requirements: 90mm shaft with 32.80kN (≈3343kg) dynamic load capacity, 2,000 RPM grease lubrication, 125×18mm profile

Robotic Joints

  • Large robotic arm pivots
  • Automated assembly joints
  • Material handling arms
  • Inspection robot pivots
  • Medical robotic joints
  • CNC machine wrist pivots
  • Manufacturing robot bases
  • Precision actuator joints

Key Requirements: Precision 90mm bore with 31.50kN (≈3212kg) static load

Heavy Machinery

  • Mining equipment shafts
  • Construction vehicle pivots
  • Agricultural machinery shafts
  • Industrial crane joints
  • Bulk material handling
  • Manufacturing machinery shafts
  • Heavy duty conveyor rollers
  • Large equipment drives

Key Requirements: 90mm bore, 18mm width for heavy machinery

Compatible Models & Shaft Requirements

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

🔄Related Models

6818 (90×115×13mm) 16018 (90×140×16mm) 6018 (90×140×24mm) 62218 (90×160×40mm) 6218 (90×160×30mm) 6318 (90×190×43mm) 62318 (90×190×64mm)

🔧Shaft Requirements

Nominal Diameter 90.000mm
Tolerance Grade h6 (89.978-90.000mm)
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 90mm bore (ID) with 6818, 16018, 6018, so it can be considered where the shaft is fixed at 90mm. The 6918 is rated 32.80kN dynamic / 31.50kN static at 125mm OD — more capacity than the 6818 (19.50kN) and less than the heavier-duty 16018 (41.50kN).

💰Value Engineering

Best value in small-bearing category for 32.80kN performance. Quality bearings last 3-10x longer than cheap alternatives, reducing total cost of ownership.

FREQUENTLY ASKED QUESTIONS

Expert guidance for 6918 bearing applications

Bearing Selection & Replacement ▼

What makes the 6918 bearing suitable for high-speed applications?

The 6918 bearing is designed for high-speed applications with a grease RPM rating of 2,000 and oil RPM of 3,400, making it ideal for precision machinery and high-speed equipment.
Why This Matters
High-speed capability ensures reliable performance in demanding applications without premature failure or excessive heat generation.
How To Handle It
Select 6918 bearing for applications requiring speeds up to 2,000 RPM with proper lubrication and mounting practices.
For maximum speed performance, use oil lubrication and ensure proper shaft and housing tolerances (h6 shaft tolerance recommended).

Can I replace a 6918 bearing with other series bearings?

The 6918 bearing can be cross-referenced with 6018, 6218, 6318, and 6818 series bearings that share the same 90mm bore diameter, though load capacities and dimensions may vary.
Why This Matters
Proper cross-referencing ensures compatibility while allowing flexibility in bearing selection based on specific application requirements.
How To Handle It
Verify outer diameter (115mm) and width (13mm) compatibility before replacement, and consider load requirements when selecting alternatives.
Always check the specific application requirements and consult technical specifications before making cross-series replacements.

What is the load capacity of the 6918 bearing?

The 6918 bearing has a dynamic load rating of 2040.0kg (20.00kN) (2040kg) and static load rating of 20.20kN (2060kg), making it suitable for moderate to high-load applications.
Why This Matters
Understanding load capacity is crucial for proper bearing selection and preventing premature failure due to overloading.
How To Handle It
Calculate your application's equivalent dynamic load and ensure it doesn't exceed 2040.0kg (20.00kN) for optimal bearing life.
For applications with high static loads, ensure the static load rating of 2060.4kg (20.20kN) is not exceeded to prevent permanent deformation.
Installation & Maintenance ▼

What shaft tolerance is recommended for the 6918 bearing?

The 6918 bearing requires an h6 shaft tolerance with a nominal diameter of 90.000mm and tolerance range of 89.987-90.013mm for optimal performance.
Why This Matters
Proper shaft tolerance ensures correct fit and prevents issues like excessive clearance or interference that can lead to premature failure.
How To Handle It
Machine the shaft to h6 tolerance (89.987-90.013mm) with a surface finish of Ra 0.8μm maximum and runout tolerance of 0.013mm maximum.
Use precision measuring tools to verify shaft dimensions before installation, as even small deviations can significantly impact bearing performance.

How should I lubricate the 6918 bearing?

The 6918 bearing can be lubricated with grease (up to 2,000 RPM) or oil (up to 3,400 RPM), with the choice depending on speed requirements and application conditions.
Why This Matters
Proper lubrication is essential for bearing performance, reducing friction, preventing wear, and extending service life.
How To Handle It
For high-speed applications, use oil lubrication. For general applications, use high-quality bearing grease with appropriate viscosity.
Avoid over-lubrication as it can cause excessive heat generation and reduce bearing efficiency, especially in high-speed applications.

What is the recommended installation method for the 6918 bearing?

The 6918 bearing should be installed using proper bearing installation tools, ensuring even pressure distribution and avoiding damage to the bearing components.
Why This Matters
Proper installation prevents bearing damage, ensures correct fit, and maximizes service life while maintaining performance characteristics.
How To Handle It
Use bearing installation tools or sleeves to apply pressure evenly on the inner ring, never apply force directly to the outer ring or balls.
Heat the bearing to 80-100°C before installation to expand the inner ring, making installation easier and reducing the risk of damage.
Troubleshooting ▼

Why is my 6918 bearing running hot?

A hot-running 6918 bearing is typically caused by over-lubrication, excessive load, misalignment, or insufficient clearance, requiring immediate investigation and correction.
Why This Matters
Excessive heat can lead to premature bearing failure, lubricant breakdown, and potential damage to surrounding components.
How To Handle It
Check lubrication levels, verify load conditions, inspect for misalignment, and ensure proper clearance. Reduce speed if necessary and monitor temperature.
Use infrared thermometers to monitor bearing temperature during operation - temperatures above 80°C indicate potential problems requiring attention.

What causes excessive noise in the 6918 bearing?

Excessive noise in the 6918 bearing is usually caused by contamination, insufficient lubrication, bearing damage, or improper installation, each requiring specific corrective actions.
Why This Matters
Unusual noise often indicates bearing problems that, if left unaddressed, can lead to catastrophic failure and equipment damage.
How To Handle It
Inspect for contamination, check lubrication levels, examine bearing surfaces for damage, and verify proper installation and alignment.
Use vibration analysis tools to detect bearing problems early, as noise often precedes visible damage and can be caught before failure occurs.

How do I identify if my 6918 bearing needs replacement?

Signs that your 6918 bearing needs replacement include excessive noise, vibration, heat generation, increased friction, or visible damage to bearing components.
Why This Matters
Timely bearing replacement prevents catastrophic failure, reduces downtime, and protects other equipment components from damage.
How To Handle It
Monitor bearing performance regularly, conduct vibration analysis, and inspect for visual signs of wear or damage during maintenance intervals.
Establish a preventive maintenance schedule based on operating conditions - high-speed applications may require more frequent inspection and replacement.
Cost & Performance ▼

What is the cost-benefit of choosing the 6918 bearing over alternatives?

The 6918 bearing offers excellent value with 2040.0kg (20.00kN) load capacity in a compact 90x125x18mm design, providing 3-10x longer service life than cheap alternatives.
Why This Matters
Quality bearings reduce total cost of ownership through longer service life, reduced maintenance, and fewer unplanned failures.
How To Handle It
Calculate total cost of ownership including initial cost, maintenance, and downtime costs when comparing bearing options.
Consider the cost of equipment downtime and replacement labor when evaluating bearing options - quality bearings often pay for themselves through reduced maintenance costs.

How can I optimize the performance of my 6918 bearing?

Optimize 6918 bearing performance by ensuring proper installation, correct lubrication, appropriate load conditions, and regular maintenance according to manufacturer specifications.
Why This Matters
Optimized performance extends bearing life, reduces maintenance costs, and ensures reliable operation in demanding applications.
How To Handle It
Follow manufacturer guidelines for installation, use recommended lubricants, monitor operating conditions, and establish regular maintenance schedules.
Implement condition monitoring systems to track bearing performance and identify optimization opportunities before problems occur.

What factors affect the service life of the 6918 bearing?

The service life of the 6918 bearing is affected by load conditions, speed, lubrication quality, operating temperature, contamination levels, and installation practices.
Why This Matters
Understanding factors that affect service life helps optimize operating conditions and maximize bearing performance and longevity.
How To Handle It
Control operating conditions within recommended limits, maintain proper lubrication, prevent contamination, and ensure correct installation and alignment.
Keep detailed records of operating conditions and maintenance activities to identify patterns and optimize bearing service life over time.
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