How lubricants work: the science behind smooth operation

Lubricants play a crucial role in efficiently operating machinery, engines, and various mechanical systems. They are essential for reducing friction, preventing wear and tear, and ensuring that industrial equipment runs smoothly and lasts longer. This article will explore what lubricants are, the different types available, how they work, and their vital functions in maintaining peak performance and longevity in industrial applications.

What are lubricants?

The word "lubricant" comes from the Latin word "lubricare," which means "to make slippery" or "to smooth." This Latin verb itself derives from the adjective "lubricus," meaning "slippery." In essence, the origin of the word reflects its primary function: making surfaces smooth and reducing friction. This etymology underscores the importance of lubricants in various applications, from industrial machinery to everyday items, by highlighting their role in facilitating smooth and efficient movement.

Lubricants are substances (typically liquids, greases, and gases) that reduce friction between surfaces in mutual contact (Metal-to-Metal, Metal-to-Non-Metal, Wood-to-Wood, Ceramic-to-Metal, and many others). They are primarily used to reduce the heat generated when the surfaces move.

Here are a couple of fun historical facts about the uses of lubricant in ancient times:

- Ancient Egyptian Lubrication Techniques: The Egyptians are known to have used animal fats and oils to lubricate the axles of chariots and other wheeled vehicles. They also used lubricants in the construction of the pyramids, applying oil to reduce friction when moving large stone blocks.

- Roman Chariot Wheels: The Romans used olive oil to lubricate the axles of their chariots and carts. This practice helped reduce vehicle wear and tear and ensure smoother transportation. While fat grease and olive oil were rudimentary compared to today's advanced formulations, they laid the foundation for the development of more effective lubricants.

Modern lubricants have evolved significantly, incorporating synthetic materials, complex chemical additives, and specialized formulations to meet the demands of various industries and applications.

Types of lubricants

The main types of lubricants include oils, greases, and solid lubricants.

Liquid (Oil) lubricants

These are the most common types of lubricants used in various applications, from engines to industrial machinery. Oils can be mineral-based (derived from the refining of crude oil), synthetic (formulated by combining conventional mineral oil with synthetic base oils), or semi-synthetic (formulated using chemically engineered base oils synthesized from chemical compounds rather than being directly derived from crude oil). Each type comes with its own set of properties and advantages.

Oil lubricants' primary function is to reduce friction and wear between moving parts, enhance efficiency, and extend the lifespan of equipment.

Oil lubricants are used in many sectors. Here are just a few examples of their many usesAutomotive Engine Oil: Motor oil is used in car engines to keep moving parts lubricated, reduce friction and wear, and cool the engine.

- Industrial Gear Oil is used in a factory's gearbox to ensure smooth operation of the gears, reduce friction, and prevent wear.
- Aviation Turbine Oil: Used in commercial aircraft engines to ensure reliable operation at high temperatures and altitudes.
- Marine Engine Oil: Lubricates the engines of cargo ships, protecting them from the corrosive marine environment.
- Hydraulic Fluid in Construction Equipment: Used in the hydraulic systems of excavators to provide efficient power transmission and lubrication.

For a high-performance, fully synthetic oil lubricant suitable for a wide range of applications, consider Lubron SX EP21 Universal Lubricant from Eco-Point Laboratories. This clear lubricant incorporates PTFE for enhanced lubrication and protection, making it ideal for environments where cleanliness and performance are crucial.

Grease lubricants

Grease is a semi-solid lubricant composed of oils and a thickener. It is particularly useful in applications where liquid lubricants would not stay in place due to factors like gravity, centrifugal forces, or the need for long-lasting lubrication. Here are some examples of such applications:

1. Bearings

Roller Bearings: Grease is used in roller bearings to provide consistent lubrication and prevent the lubricant from leaking out due to rotational forces.
Ball Bearings: Grease is applied to ball bearings in machinery to ensure they remain lubricated over extended periods, even when subjected to high-speed rotations.

2. Automotive applications

Wheel Bearings: Grease is essential for lubricating wheel bearings as it stays in place despite the wheels' rotational movement and high temperatures.
Chassis Components: Suspension joints, ball joints, and other chassis components are greased to ensure they remain lubricated despite exposure to dirt, water, and vibrations.

3. Heavy machinery and construction equipment

Excavator Pins and Bushings: Grease is used to lubricate excavator pins and bushings subjected to heavy loads and movements, ensuring the lubricant stays in place.
Cranes and Loaders: Moving parts in cranes and loaders are greased to provide long-lasting lubrication in challenging environments.

For instance, if you're looking for a high-performance grease suitable for high-load and extreme water contact applications, consider Duron Aquashield EP38 Lubricating Grease. This premium, long-life lubricant is designed to withstand extreme conditions while providing excellent mechanical and oxidation stability.

Solid lubricants

These include materials like graphite, molybdenum disulfide, and PTFE (Teflon). Solid lubricants are used in extreme conditions where traditional lubricants might fail, such as high-temperature environments or vacuum conditions. Check out our latest article on solid lubricants and how they work.

Now that we know what lubricants are and the types they are divided into, let’s talk about the science behind them.

The science behind lubricants

Lubricants are pivotal in machinery by minimizing friction and wear between contacting surfaces, thereby ensuring efficient operation. To grasp their function, it's essential to delve into the underlying science of friction.

Understanding friction

Friction occurs when two surfaces move against each other, influenced mainly by the force pressing them together (known as the "load"). Surprisingly, the contact area between surfaces doesn't significantly alter friction—a counterintuitive aspect that sheds light on lubricant mechanics.

At a microscopic level, friction arises from surface irregularities and microscopic bumps that create a subtle adhesive effect. This phenomenon is attributed to van der Waals forces, a weak form of electromagnetism where molecules from one surface attract those of another. Despite each molecule exerting a minuscule force, their cumulative effect leads to noticeable friction.

How lubricants reduce friction

Lubricants, typically in liquid form like oils, act as a protective barrier between surfaces, effectively reducing friction and wear. Here's how they achieve this:

Flow and adaptability

Unlike solids, liquids can flow and adapt to their surroundings. Lubricants like oil conform to microscopic imperfections and bumps when applied between surfaces, such as gears. This adaptive quality cushions the surfaces, preventing direct metal-to-metal contact and reducing friction.

Layer formation

Ideally, lubricants form thin layers that glide over each other smoothly—a phenomenon known as laminar flow. Picture two layers: the upper layer moving with one surface (e.g., a gear) in one direction, and the lower layer moving with the opposing surface in the opposite direction. This seamless interaction minimizes resistance and maximizes efficiency.

Microscopic interaction

Despite forming layers, lubricants at a microscopic scale are incredibly thin—sometimes just a few molecules thick. These thin layers can still experience contact in instances where surface imperfections persist, leading to occasional snags or breaks. Lubricants may also chemically react with surfaces to enhance lubrication, a process termed boundary or boundary-film lubrication.

Choosing the right lubricant

Selecting the appropriate lubricant for a specific application involves considering several factors, including the operating temperature, load, speed, and environmental conditions. The right choice ensures optimal performance and longevity of the machinery.

For instance, imagine using regular water as a lubricant in an engine. While water might reduce friction temporarily, it would quickly evaporate or even boil away as the engine heats up. Water evaporates at 100°C (212°F), but engine parts can reach much higher temperatures. This would leave the engine parts unprotected, leading to increased friction, overheating, and potential damage. In contrast, properly formulated engine oil can withstand these high temperatures, maintaining a protective layer that reduces friction and wear, ensuring the engine runs smoothly and efficiently.

The right choice ensures optimal performance and longevity of the machinery.

Conclusion

Understanding how lubricants work is essential for anyone involved in maintaining and operating industrial machinery. Lubricants are indispensable in keeping equipment running smoothly and efficiently by reducing friction, dissipating heat, preventing wear, protecting against corrosion, and removing contaminants. Investing in high-quality lubricating products can lead to significant cost savings and operational efficiencies in the long run.

Eco-Point has the expertise to guide you when choosing the ideal lubricant. Our team is always on hand to help, whether it’s for advice on the appropriate formula for your project, or to find out more about the specifications and uses for our products. Contact us today by phone on +44(0)14 9479 2803, by email at [email protected], or via our handy online form.