Grease Explained: Understanding Its Ingredients and Functions


When you’re wondering what is grease and why it matters, here’s a quick answer: Grease is a thick lubricant made from oil and a thickening agent. It sticks where applied, ensuring smooth machinery operations without leaking away like oil might.

  • Definition: Grease is a semi-fluid or solid lubricant.
  • Importance: It ensures equipment runs efficiently and lasts longer.
  • Overview: Used widely in industries like automotive and manufacturing, grease is crucial for optimal machinery performance.

Think of grease as a blend that stays put, unlike oil, which can drip away. It’s crucial in making sure your machine parts move smoothly and don’t wear out quickly. For manufacturing companies, using the right grease means less downtime and fewer breakdowns.

My name is Todd Cleppe, and I have over 25 years of experience in designing and improving machinery systems at CFAB Global. I’ve used my expertise to ensure machinery runs efficiently by understanding what is grease and its role in lubrication. Next, let’s dive into what goes into making grease and how it works for different applications.

Infographic explaining what is grease and its importance - what is grease infographic brainstorm-6-items

What is Grease?

Composition of Grease

Grease is a semi-fluid to solid lubricant. It’s made by mixing a liquid lubricant (usually oil) with a thickening agent. This mix keeps grease in place, ensuring it provides consistent lubrication.

Base Oil (70-90%): The main ingredient in grease is base oil. Most greases use mineral oil because it works well in many situations. However, for extreme temperatures, synthetic oils are better due to their stability.

Thickeners (5-20%): Thickeners give grease its unique consistency. These are often metallic soaps like lithium, calcium, or sodium. Some greases use complex agents like polyurea. The thickener acts like a sponge, holding the oil and additives together.

Additives (1-10%): Additives improve grease performance. Common additives include:

  • Oxidation inhibitors: Prevent grease from breaking down.
  • Rust inhibitors: Protect metal surfaces.
  • Extreme pressure agents: Help grease perform under high loads.
  • Anti-wear compounds: Reduce wear and tear on machinery parts.

Types of Grease

Grease can be classified by the type of thickener used:

Metallic Soaps: These are the most common thickeners. They include lithium, calcium, sodium, and aluminum. Each type has its own benefits:

  • Lithium: Good for general use, stable in both high and low temperatures.
  • Calcium: Excellent water resistance, often used in marine applications.
  • Sodium: Good for high-temperature applications but not water-resistant.
  • Aluminum: High water resistance and good for high-temperature applications.

Non-soap Thickeners: These include materials like bentonite and silica aerogel. They are used for high-temperature environments because they don’t melt like soap-based thickeners.

Complex Agents: These are a combination of metallic soaps and other agents. They offer higher dropping points and better load-carrying abilities.

Common Applications of Grease

Grease is used in various industries due to its staying power and ability to provide consistent lubrication.

Industrial Applications: In factories, grease is used to keep machinery running smoothly. It’s applied to conveyor belts, gears, and other moving parts. Using the right grease can reduce downtime and maintenance costs.

Automotive Industry: Grease is crucial for vehicle maintenance. It’s used in wheel bearings, chassis, and suspension systems. Proper lubrication ensures that these parts don’t wear out quickly, improving the vehicle’s lifespan.

Aerospace: In the aerospace industry, grease is used in aircraft components that experience high loads and extreme temperatures. It ensures that these parts operate efficiently and safely.

Grease is a vital component in many industries. Understanding its composition and types can help you choose the right grease for your needs. Next, we’ll explore how grease works and the science behind its lubrication properties.

How Grease Works: The Science Behind the Substance

Lubrication Mechanism

Grease is a unique lubricant because it combines the properties of both liquids and solids. It’s made up of a base oil, thickeners, and various additives. The base oil provides the actual lubrication, while the thickener holds the oil in place and gives the grease its semi-solid structure.

The lubrication mechanism of grease involves forming a film between moving parts. This film reduces friction and wear, ensuring smooth operation. According to Cann et al., the grease structure starts to break down into smaller clumps as it approaches the contact area, creating a continuous lubricating film.

Shear Thinning and Consistency

Grease exhibits a property known as shear thinning. This means that its viscosity decreases with an increase in shear rate. When you apply pressure or shear to the grease, it becomes less viscous and flows more easily. This property is crucial for applications where the grease needs to move into tight spaces under pressure.

Consistency is another important characteristic of grease. It determines how well the grease stays in place and maintains its lubricating properties under different conditions. The consistency of grease is influenced by the type and amount of thickener used. For example, lithium-based greases are known for their high-temperature tolerance and good mechanical stability.

Film Formation

The process of film formation in grease involves the thickener fibers and base oil working together. As the grease is subjected to shear, the thickener fibers break down and release the base oil, which forms a lubricating film. This film provides a barrier between moving parts, reducing friction and wear.

Grease film formation mechanism according to Cann et al. - what is grease

In the study by Williamson, it was found that the type of thickener can significantly influence the film thickness. For instance, lithium-thickened greases tend to form thicker films at medium speeds compared to calcium-thickened greases.

Load Carrying

Grease is designed to handle varying loads and stresses. Its ability to carry loads is determined by its yield stress, the minimum stress required to make the grease flow. Greases with higher yield stress can withstand greater loads without breaking down. This property is essential for applications like bearings and gears, where high loads are common.

Viscosity Changes

The viscosity of grease changes with temperature and shear rate. At low shear rates, grease maintains a high viscosity, which helps it stay in place. As the shear rate increases, the viscosity decreases, allowing the grease to flow and provide lubrication where needed.

Schematic of the rheological behavior of base oil (Newtonian) and grease (shear-thinning with yield stress) - what is grease

Understanding these viscosity changes is crucial for selecting the right grease for specific applications. For example, in high-speed machinery, a grease with appropriate shear-thinning properties ensures efficient lubrication without excessive energy consumption.

Application Impact

The unique properties of grease, such as shear thinning and high consistency, make it ideal for applications where liquid lubricants would fail. Grease stays in place, resists leakage, and provides long-lasting lubrication. This makes it perfect for machinery with infrequent maintenance intervals or components exposed to harsh environments.

In summary, the science behind grease involves its ability to form a lubricating film, handle varying loads, and adapt its viscosity according to the application. These properties make grease an indispensable lubricant in many industrial applications.

Next, we’ll compare grease with oil and explore their differences, advantages, and suitability for various applications.

Comparing Grease and Oil

Key Differences

Physical State: Grease is a semi-solid, while oil is a liquid. This difference in consistency means that grease stays in place better than oil. It doesn’t flow away from the parts it lubricates, making it ideal for components that need lubrication over long periods without frequent maintenance.

Application Methods: Applying grease usually involves a grease gun or a similar tool, which makes it easier to apply in hard-to-reach areas. Oil, on the other hand, often requires a more complex system like drip-feed or recirculation to ensure it reaches the necessary parts.

Sealing Properties: Grease acts as a sealant, preventing contaminants like dust, dirt, and water from entering the machinery. This sealing capability is a significant advantage over oil, which generally lacks this property and may require additional sealing mechanisms.

Advantages of Grease Over Oil

Longevity: Grease provides longer-lasting lubrication compared to oil. It stays in place and continues to lubricate even under high pressure or in vertical applications. This makes it perfect for machinery with infrequent maintenance schedules.

Sealing: Grease’s semi-solid state forms a barrier that seals out contaminants. This is crucial in environments where machinery is exposed to dirt, dust, or water. For example, in food processing and packaging, using grease helps prevent contamination, ensuring safer and cleaner operations. Companies like Beth-El Machinery Ltd. offer specialized equipment that benefits from these sealing properties.

Contaminant Prevention: The thick consistency of grease helps to trap and hold particles, preventing them from causing wear and damage to machinery. This is particularly beneficial in harsh environments like mining or construction where equipment is exposed to a lot of debris.


Intermittent Operation: Grease is ideal for machinery that doesn’t run continuously. It stays in place even when the machine is off, providing immediate lubrication when the machine starts again.

Inaccessible Lubrication Points: For parts that are hard to reach, grease is more practical. It can be applied once and remain effective for a long time, unlike oil, which might need frequent reapplication.

Extreme Conditions: Grease is better suited for extreme conditions, whether it’s high temperatures, heavy loads, or shock loads. Its ability to maintain consistency and provide effective lubrication makes it invaluable in such settings.

In conclusion, while both grease and oil serve essential roles in lubrication, their differences in physical state, application methods, and sealing properties make them suitable for different applications. Grease offers significant advantages in terms of longevity, sealing, and contaminant prevention, making it a preferred choice for many industrial applications.

Grease Standards and Classification

Understanding the standards and classifications of grease is key to choosing the right lubricant for your machinery. This section will cover the NLGI grading system, ASTM standards, and ISO classifications.

NLGI Grading System

The National Lubricating Grease Institute (NLGI) grading system is a widely accepted method for classifying grease based on its consistency. This system uses a scale from 000 to 6:

NLGI Grade Consistency Typical Applications
000 Extremely Fluid Centralized lubrication systems, gearboxes
00 Very Fluid Semi-fluid applications, enclosed gears
0 Fluid Centralized systems, underbody automotive
1 Semi-Fluid Colder temperatures, electric motors
2 Moderate General-purpose automotive, industrial
3 Firm High temperature, where grease migration is a concern
4 Very Firm Sealed-for-life applications, certain bearings
5 Hard High-load, minimal leakage situations
6 Very Hard Specialized applications with limited mobility

Grades 2 and 3 are the most commonly used, especially in automotive and industrial applications. The NLGI grade is determined by measuring the penetration of a standard cone into the grease, which indicates its consistency.

ASTM and ISO Standards

ASTM D4950 is a standard developed by ASTM International, in collaboration with the NLGI and SAE International. It classifies greases for automotive service based on performance requirements. The standard uses codes like LA, LB for chassis lubricants and GA, GB, GC for wheel-bearing lubricants, indicating their suitability for different levels of duty.

ISO 6743-9, published by the International Organization for Standardization, provides a detailed classification for industrial greases. This standard assigns a multi-part code to each grease based on its operational properties, such as temperature range and water resistance, along with its NLGI consistency number.

Both ASTM and ISO standards help ensure that the grease you choose meets specific performance criteria, making it easier to select the right product for your machinery.

Performance Categories

Performance categories in grease standards help users understand the suitability of a grease for various applications. For instance, ASTM D4950 uses categories like:

  • LA and LB: Chassis lubricants for mild to severe duty.
  • GA, GB, GC: Wheel-bearing lubricants for mild to severe duty.

ISO 6743-9 also provides performance categories based on operational properties, ensuring that the selected grease can handle the specific demands of your machinery.

These standards and classifications are essential for ensuring that the grease you use will perform effectively under the conditions it will face, whether in automotive, industrial, or specialized applications.

This section leads directly into the next part of the article, which will explore the industrial applications and benefits of grease, particularly focusing on how it protects machinery and enhances operational efficiency.

Industrial Applications and Benefits of Grease

Grease is a vital lubricant in many industries, offering protection and efficiency that oils can’t always provide. Let’s dive into how it’s used in the automotive, manufacturing, and aerospace sectors.

Automotive Industry Uses

Chassis and Wheel Bearings

Grease is crucial for lubricating chassis components and wheel bearings in vehicles. Its ability to withstand heavy loads and resist water contamination makes it ideal. As noted by Baart, grease plays a key role in ensuring these parts operate smoothly over long periods.

Suspension Systems

High-performance greases are essential in suspension systems. They endure varying temperatures and pressures, providing consistent performance. This ensures a smoother ride and longer-lasting components.

Manufacturing and Aerospace Applications

Conveyor Belts and Motor Bearings

In the manufacturing sector, grease is indispensable for conveyor belts and motor bearings. It reduces wear and tear, prolonging the equipment’s life. This leads to fewer breakdowns and more efficient operations, as highlighted by Cann.

High-Load Machinery

For heavy machinery, grease provides lubrication under high pressure and load. This is critical for maintaining smooth operation and preventing breakdowns. It ensures that high-load machinery can handle demanding tasks without frequent maintenance.

Aircraft Components

In the aerospace industry, specialized synthetic greases are used for aircraft components like bearings, gears, and control systems. These greases must perform reliably under extreme temperature variations and pressures. Research by Briscoe shows that these greases are essential for the safety and efficiency of aircraft operations.

CFAB Global’s Machine Reliability Program

CFAB Global offers a Machine Reliability Program that leverages the benefits of grease lubrication to enhance machinery performance. This program focuses on:

  • Machinery Protection: Grease forms a protective barrier against wear and corrosion, extending the lifespan of your equipment.
  • Operational Efficiency: Proper grease lubrication reduces friction, leading to smoother operations and less energy consumption.

By understanding the specific needs of different industries, CFAB Global provides tailored solutions that ensure optimal performance and reliability of machinery. Whether it’s for automotive chassis, manufacturing conveyor belts, or aerospace components, CFAB Global’s expertise in grease lubrication helps keep your machinery running smoothly.


CFAB Global

In summary, grease plays a crucial role in ensuring the longevity and efficiency of machinery across various industries. From its composition to its diverse applications, grease provides essential lubrication, protection from contaminants, and operational stability.

At CFAB Global, we understand the importance of reliable machinery solutions. Our expertise in grease lubrication is part of our larger commitment to enhancing machinery performance.

Our Machine Reliability Program is designed to address the unique challenges faced by different industries. This program focuses on:

  • Machinery Protection: Grease acts as a barrier against wear and corrosion, significantly extending the lifespan of machinery components.
  • Operational Efficiency: Properly applied grease reduces friction, resulting in smoother operations and lower energy consumption.

We offer customized machinery solutions tailored to meet your specific needs. Whether you operate in the automotive, manufacturing, or aerospace sectors, our team is equipped to provide the optimal lubrication solutions that ensure your machinery runs smoothly and efficiently.

For more information on how CFAB Global can support your machinery needs, visit our Automated Lubrication System page.

Trust CFAB Global to keep your operations running smoothly and efficiently.

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