Grease

Selection Guidelines:

Choose Grease When:

• Bearing speeds < 70% of dn limit
• Open systems difficult to seal
• Intermittent operation equipment
• Extreme environmental conditions
• Remote or inaccessible locations

Choose Oil When:

• High-speed equipment (dn > 500,000)
• Heat dissipation required
• Precision control systems
• Circulating lubrication systems
• Continuous high-speed operation

Cost-Benefit Analysis:

While grease may cost more initially, its extended service life and reduced maintenance requirements often result in 30-50% lower total cost of ownership compared to oil lubrication systems.

The NLGI (National Lubricating Grease Institute) grade measures grease consistency from 000 to 6, indicating how thick or thin the grease is.

NLGI Grade Reference Table:

Selection Guidelines:

• NLGI 2: Universal choice for most bearing applications
• NLGI 1: High-speed bearings, low-temperature environments
• NLGI 3: Heavy-duty equipment, high-temperature applications
• NLGI 00/000: Centralized lubrication systems, remote pumping

Temperature Effects:

For every 15°C (27°F) temperature increase, grease consistency typically drops by approximately one NLGI grade.

Application Examples:

• Automotive wheel bearings: NLGI 2
• Electric motor bearings: NLGI 1-2
• Heavy construction equipment: NLGI 2-3
• Centralized lubrication: NLGI 000-00

Classification by Thickener:

1. Lithium Grease

• Temperature Range: -20°C to +120°C (-4°F to +248°F)
• Characteristics: Versatile, cost-effective, water-resistant
• Applications: Automotive bearings, general industrial equipment
• Market Share: Approximately 70%

2. Complex Lithium Grease

• Temperature Range: -30°C to +180°C (-22°F to +356°F)
• Characteristics: Superior high-temp performance, excellent water resistance
• Applications: Heavy equipment, high-temperature bearings
• Recommended for: Caterpillar, Komatsu, John Deere equipment

3. Polyurea Grease

• Temperature Range: -40°C to +200°C (-40°F to +392°F)
• Characteristics: Extended service life, excellent high-speed performance
• Applications: Electric motor bearings, high-speed spindles
• Advantage: 2-3x longer service life than lithium-based greases

4. Aluminum Complex Grease

• Temperature Range: -30°C to +150°C (-22°F to +302°F)
• Characteristics: Excellent EP properties, superior water resistance
• Applications: Marine equipment, wet environments

Specialty Application Greases:

Food Grade Grease (NSF H1)

• Certification: FDA 21 CFR 178.3570, NSF H1
• Base Oil: PAO synthetic oil, white mineral oil
• Applications: Food processing equipment, pharmaceutical machinery
• Safety: Incidental food contact safe

High Temperature Grease

• Temperature Range: Up to +300°C (+572°F)
• Thickener: Bentonite clay, PTFE
• Applications: Steel, glass, ceramic industries
• Special Features: Non-melting thickeners for extreme heat

Marine Grease

• Environment: Salt water, high humidity
• Thickener: Aluminum complex, calcium sulfonate
• Additives: Anti-corrosion, anti-foam
• Standards: Meets marine classification society requirements

Mining Industry

Challenges: Heavy dust, extreme loads, harsh conditions Recommended Solutions:

• Thickener: Complex lithium, polyurea
• NLGI Grade: 2-3
• Special Requirements: Superior wear protection, excellent sealing
• Typical Equipment: Excavators, loaders, conveyor bearings
• Service Intervals: 500-1000 operating hours

Construction Equipment

Challenges: Temperature fluctuations, water contamination, heavy loads Recommended Solutions:

• Product: General-purpose lithium grease NLGI 2
• Service Intervals: 500-1000 operating hours
• Critical Points: Pin joints, slew ring bearings
• Performance: EP additives for heavy-duty protection

Wind Power Industry

Challenges: High-altitude maintenance difficulty, temperature variations Recommended Solutions:

• Main Bearings: Polyurea grease, 5-year maintenance-free
• Yaw Bearings: Complex lithium, anti-fretting wear
• Pitch Bearings: Low-temperature synthetic grease
• Special Requirements: Long service life, extreme weather resistance

Steel Industry

Challenges: High temperatures, steam, oxidizing environment Recommended Solutions:

• Rolling Mill Bearings: Synthetic high-temp grease (>200°C)
• Continuous Casting: Water-resistant aluminum complex grease
• Service Intervals: Adjusted based on temperature and load
• Special Features: High-temperature stability, oxidation resistance

Marine Applications

Challenges: Salt spray corrosion, high humidity Recommended Solutions:

• Thickener: Aluminum complex soap
• Additives: Anti-corrosion, salt spray resistance
• Certification: Classification society approved
• Applications: Deck machinery, propeller shaft bearings

Paper & Pulp Industry

Challenges: High moisture, chemical exposure Recommended Solutions:

• Base Oil: Synthetic for chemical resistance
• Thickener: Polyurea for long life
• Special Features: Water washout resistance
• Applications: Paper machine bearings, calendar rolls

Step 1: Determine Operating Conditions

Temperature Range:

• Low temp (<0°C/32°F) → Choose PAO synthetic base
• Normal temp (0-80°C/32-176°F) → Mineral oil base sufficient
• High temp (>120°C/248°F) → Synthetic oil + polyurea/clay thickener

Load Conditions:

• Light load → NLGI 1-2
• Medium load → NLGI 2
• Heavy load → NLGI 2-3 + EP additives

Speed Factor (dn value):

• dn < 300,000 → General-purpose grease
• dn 300,000-500,000 → Low-viscosity base oil
• dn > 500,000 → Consider oil lubrication

Step 2: Environmental Factors

Water Contamination Risk:

• Present → Aluminum complex, complex lithium
• Absent → Simple lithium acceptable

Dusty Environment:

• Severe → Prefer good sealing grease (NLGI 3)
• Normal → NLGI 2 general-purpose

Chemical Exposure:

• Acidic → Polyurea grease
• Alkaline → Aluminum complex
• Solvents → PTFE-based

Step 3: Maintenance Requirements

Service Intervals:

• Extended (>2 years) → Polyurea, PAO synthetic
• Standard (6 months-2 years) → Complex lithium
• Short (<6 months) → Economic lithium-based

Quick Selection Chart:

Compatibility Check:

Before Switching Greases:

1. Check thickener compatibility
2. Verify additive interactions
3. Consider purging requirements
4. Review OEM recommendations

Q1: How often should grease be replaced?

A: Replacement intervals depend on several factors:

• Temperature: Life halves for every 15°C (27°F) increase
• Speed: High speeds reduce service life
• Load: Heavy loads accelerate degradation
• Environment: Dust and moisture accelerate deterioration

General Guidelines:

• General applications: 6-12 months
• Harsh environments: 3-6 months
• Premium synthetic grease: 12-24 months
• Follow OEM recommendations when available

Q2: Can different grease brands be mixed?

A: Not recommended due to:

• Incompatible thickeners may cause separation
• Additives may react chemically
• Performance may significantly decrease

If changing greases:

• Remove old grease completely
• Flush with new grease
• Refill with fresh grease
• Monitor equipment performance closely

Q3: Is grease color change normal?

A: Common color changes:

• Darkening: Normal oxidation, slight darkening acceptable
• Black: Severe oxidation or contamination, replace immediately
• Thinning: Thickener structure breakdown, replace immediately
• Separation: Oil bleeding, check storage conditions

Q4: How to determine grease quality?

A: Quality indicators:

• Appearance: Smooth, uniform, no foreign matter
• Consistency: Meets NLGI grade specification
• Dropping Point: ≥180°C (356°F) for complex lithium
• Oil Separation: ≤5% (150°C, 24 hours)
• Corrosion: Copper strip corrosion ≤1 rating

Q5: What causes bearing overheating with grease?

A: Possible causes:

• Over-lubrication: Excess grease causes churning heat
• Grease degradation: Loss of lubricating properties
• Wrong viscosity: Incorrect NLGI grade selection
• Contamination: Water or particle contamination

Solutions:

• Follow proper fill quantities (1/3 to 1/2 bearing volume)
• Select appropriate NLGI grade
• Regular grease replacement
• Improve sealing conditions

Q6: What is grease bleeding and is it normal?

A: Grease bleeding (oil separation) is:

• Normal: Slight separation during storage
• Acceptable: <5% oil separation
• Concerning: Excessive separation indicates poor quality
• Action: Remix before use if separation is minimal

Q7: How to calculate relubrication quantities?

A: Formula: Grease amount (grams) = 0.005 × D × B

• D = Bearing outside diameter (mm)
• B = Bearing width (mm)
• Example: 100mm OD × 20mm width = 0.005 × 100 × 20 = 10 grams

Key Performance Indicators:

Test Standard Reference:

ASTM Standards:

• ASTM D217 – Cone Penetration (NLGI Grade)
• ASTM D566 – Dropping Point Test
• ASTM D1742 – Oil Separation Test
• ASTM D2596 – Four-Ball EP Test
• ASTM D1264 – Water Washout Resistance

ISO Standards:

• ISO 2137 – Consistency Determination
• ISO 2176 – Dropping Point Determination
• ISO 6743-9 – Grease Classification

Performance Grade Classifications:

EP (Extreme Pressure) Ratings:

• EP 0: Light-duty applications
• EP 1: Medium-duty applications
• EP 2: Heavy-duty applications
• EP 3: Extreme heavy-duty applications

Temperature Classifications:

• LT (Low Temp): Below -40°C (-40°F)
• MT (Medium Temp): -20°C to 120°C (-4°F to 248°F)
• HT (High Temp): Above 120°C (248°F)
• EHT (Extreme High Temp): Above 200°C (392°F)

Quality Control Parameters:

• Appearance: Smooth, homogeneous texture
• Mechanical Stability: ≤10% consistency change after working
• Corrosion Protection: Pass copper strip test
• Oxidation Resistance: <20% viscosity increase after 100 hours
• Low Temperature: Torque <300% increase at -40°C

Storage Requirements:

Environmental Conditions:

• Temperature: 5-35°C (41-95°F), avoid extreme temperatures
• Humidity: <70%, prevent moisture contamination
• Ventilation: Good ventilation, avoid harmful gas accumulation
• Lighting: Avoid direct sunlight exposure

Package Integrity:

• Sealing: Ensure packages remain sealed
• Labeling: Keep labels clear and readable
• Shelf Life: Generally 2-3 years from production date
• FIFO: Follow First In, First Out principle

Safety Operations:

Personal Protection:

• Gloves: Nitrile rubber gloves recommended
• Eye Protection: Safety glasses to prevent splashing
• Clothing: Protective clothing to prevent skin contact
• Hygiene: Wash hands thoroughly after handling

Emergency Response:

• Skin Contact: Wash with soap and water
• Eye Contact: Rinse with clean water for 15 minutes
• Ingestion: Do not induce vomiting, seek medical attention
• Fire: Use foam or dry chemical extinguishers

Environmental Requirements:

Waste Disposal:

• Prohibition: Cannot be disposed of casually
• Recycling: Send to qualified waste treatment facilities
• Container Cleaning: Clean thoroughly before recycling
• Record Keeping: Maintain disposal records

Spill Response:

1. Stop the source of leakage
2. Contain spread using sand or absorbent materials
3. Mechanical recovery preferred
4. Clean area with detergent solution
5. Report and record as required

Quality Assurance:

• Incoming Inspection: Appearance, consistency, certificates
• Regular Checks: Quarterly storage condition assessment
• Temperature Monitoring: Record storage environment temperature
• Shelf Life Management: Establish inventory tracking system

Material Safety Data Sheet (MSDS) Requirements:

• Product Identification: Complete product information
• Hazard Classification: GHS compliant labeling
• First Aid Measures: Emergency response procedures
• Fire-Fighting: Appropriate extinguishing methods
• Handling Precautions: Safe work practices
• Storage Conditions: Proper storage requirements
• Regulatory Information: Compliance with local regulations

Transportation Guidelines:

• Packaging: Use approved containers
• Labeling: Proper hazard communication
• Documentation: Required shipping papers
• Temperature Control: Maintain appropriate temperatures
• Segregation: Separate from incompatible materials

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