Lubricant

The different types of lubricants

There are 3 main types of mechanical lubricant: oils, greases and pastes.

The main variables don't change for these 3 types of lubricant, but when choosing, viscosity and flash point must be taken into account.

Viscosity

Viscosity is considered the most important property of a lubricant, as it determines the lubricant's resistance and effectiveness in preventing friction between moving parts.
A higher-viscosity oil can withstand higher pressure without being expelled from lubricating surfaces. However, the oil's high internal friction may offer greater resistance to movement of lubricating parts.
Lower viscosity oil offers less resistance to moving parts, but the oil can be easily removed from lubricating surfaces.

Using an oil with an incorrect viscosity, whether too high or too low, can lead to a series of problems with the equipment.

 

Viscosity effects

• Low viscosity : Offers less resistance to moving parts, facilitating movement and reducing energy consumption. However, it can easily be pushed off surfaces, leading to insufficient lubrication, increased heat and accelerated wear.
• High viscosity : Creates a thick film between parts, offering superior wear protection. However, it can also lead to increased resistance to movement, higher energy consumption and start-up difficulties in cold conditions.

 

What is the viscosity index ?

The viscosity index of the oil is expressed by the values attached to the letter W. The numbers preceding the W refer to the cold dynamic viscosity.

The numbers following the letter W indicate the hot grade, otherwise known as the kinematic hot viscosity.

 

Oils

Oil lubricants, often simply referred to as "lubricating oil", are substances used to reduce friction, heat and wear between two surfaces. The use of lubricants is crucial in many fields, from automotive to industrial, domestic and specialized applications.

Here are some key points about oil lubricants:

Types

• Mineral : Derived from crude oil, these are the most common oils used in a variety of applications.
• Synthetics : Chemically manufactured to offer superior performance in extreme conditions such as very high or very low temperatures.
• Semi-synthetic : Combination of mineral and synthetic oils, offering a balance between performance and cost.
• Vegetal : Derived from plant sources, they are biodegradable and used in applications requiring environmentally-friendly products.

Applications

• Automotive : Engine oils, transmission oils, hydraulic fluids.
• Industrial : Lubrication of machines, hydraulic systems, gears, compressors.
• Specialized : Applications requiring specific properties, such as food equipment or extremely low-temperature applications.

The use of oil lubricants is essential to reduce wear and extend the life of mechanical components. They play a crucial role in reducing maintenance and operating costs, while improving the efficiency and reliability of equipment and vehicles.

Grease

Composed of a base oil, a thickener and, often, additives that improve certain properties such as resistance to pressure, water or corrosion.
Here are some key points about grease lubricants:

Thickeners and additives

Thickeners give grease its semi-solid consistency. They can be soap-based, such as lithium, calcium or aluminum, or soap-free, such as bentonite or polyurea.
Additives can include anti-wear agents, antioxidants, corrosion inhibitors and dropping point improvers. They are added to protect against extreme or specific conditions of use.

Applications

Grease is used in a wide variety of applications, from vehicle bearings to industrial equipment, from household appliances to tools.
It's particularly useful where lubricant needs to stay in place, or where it's difficult to apply oil regularly.
The grease adheres well to surfaces and works well under extreme load and temperature conditions.

Limitations

Greases are not suitable for all applications, especially at very high speeds or in environments where grease could contaminate products (as in the food industry).
In addition, the wrong choice of grease can cause compatibility problems with materials or other lubricants.

Maintenance

Good maintenance practice involves regularly checking the condition of the grease, and replacing or topping up as necessary to ensure continuous protection and prevent debris build-up or oxidation.

 

Paste

Paste lubricant is a specific form of lubricant designed to provide effective lubrication under difficult conditions.

Composition and properties

Paste lubricants generally consist of greases thickened with solid agents such as molybdenum disulphide (MoS2), graphite or PTFE. These solid agents provide a lubricating layer that can withstand high loads and extreme temperatures.

Applications

Paste lubricants are often used in industrial, mechanical and automotive applications. They are particularly useful for lubricating components subject to very heavy loads, oscillating or low-amplitude movements, or where operating conditions can lead to rapid degradation of liquid or conventional lubricants.

Benefits

The main advantage of paste lubricants is their ability to maintain effective lubrication in extreme conditions where other types of lubricant might fail. They help reduce wear, extend component life and improve machine reliability.

Maintenance

Although paste lubricants offer long-lasting protection, periodic maintenance and replacement are essential to ensure optimum performance.

 

Which lubricant to choose?

To choose the ideal lubricant, consider the specific application, compatibility with materials in contact (metals, plastics, rubber), environmental conditions (presence of water, temperature, food or pharmaceutical industry), and performance requirements (corrosion resistance, pressure load).

 

How do I apply lubricant?

Correct application of the lubricant is essential to maximize its effect.
Use a burette for oils, allowing precise distribution on bearings or chains.

For greases, a grease gun may be required to reach specific lubrication points under high pressure. Sprays are ideal for covering large surfaces or complex components.
Always follow the manufacturer's instructions for quantity and frequency of application, ensuring an adequate protective layer without overloading the mechanisms.

To discover our full range of lubricants and receive personalized advice on product selection and application, visit our dedicated page on 123Roulement.