Greases Guide

What are greases?

Typically, grease is a solid or semi-solid lubricant consisting of a base oil with additional additives and a thickening agent. They are often used in industrial environments, engineering, and automotive applications to keep components moving freely and smoothly. Some greases also offer protection to components against corrosion, as well as wear and tear and seizing.

Greases are commonly composed of three primary components, which helps to maintain its semi-solid form:

  • Thickener: Making between 5-20% of greases, thickeners, often in the form of soaps, function to lubricate and diminish friction between moving surfaces. They retain oil until it's required for lubrication, where it is then released once triggered by movement, vibration, or temperature fluctuations.
  • Base Oils: 80-95% of greases are usually made up of a base oil. Base oils in grease provides vital functions such as lubrication, reducing friction and wear between surfaces, enhancing load-bearing capacity of components within machinery as well as dissipating heat, and protecting components against contaminants and corrosion.
  • Additives: Working in tandem with the base oil, additives usually make up the final 0-10% of greases. Additives can serve many purposes such as enhancing the lubricating properties of greases or bolstering protection against wear and rust. Additives can help the grease's thickness to diminish under stress or shear, which makes the grease oilier and closer in consistency to its base oil. This phenomenon, known as thixotropy, sets greases apart from other similar products such as petroleum jellies.

What are greases used for?

Whilst greases are primarily used for lubricating components and moving parts to reduce friction, they also help to bolster overall longevity and efficiency of machinery and various other equipment.

Some of these uses include:

  • Protection Against Contaminants: Greases help to form a barrier which protects components or parts from contaminants such as dirt, water, dust and similar particulates.
  • Load Distribution: Greases can help to evenly distribute the load placed upon components, ensuring a longer life span of parts by reducing stress.
  • Temperature Control: Friction of components can generate heat. Greases work to dissipate the heat caused by moving parts; this can also reduce the risk of machinery overheating.
  • Noise Reduction: In addition to their primary lubrication function, some greases can also work to reduce vibrations within machinery and dampen noise created by moving parts.

Types of Greases

Bearing Greases

Bearing greases are semi-solid lubricants for use primarily on bearings. They typically consist of a blend of a base oil, additives and thickener. They are formulated to reduce friction, wear and heat build up in bearings, ensuring longevity of components and machinery.

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Multi Purpose Greases

Used most commonly in the automotive industry, multi purpose greases have wide serving properties and make lubrication simple and easy, removing the necessity for multiple grease types to be used on one application.

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Lithium Greases

Lithium grease uses lithium based soap as the primary thickening agent. It is commonly used in household and gardening applications such as on door hinges and bearings. It exhibits high viscosity, durability and stability. Ideal for metal-to-metal applications, lithium greases feature good water resistance as well as being able to withstand high pressures and shock loading.

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Considerations when choosing Greases

When choosing a type of grease, there are several important factors to consider before purchasing. By carefully taking into account these factors, you can be assured that the type of grease you choose will be suited for your requirements.

  • Additives: Additives are usually added for protection, heat resistance and a myriad of other beneficial qualities. For example, rust protection. Consider what additives may be desirable or necessary for your intended application.
  • Base Oil: As a general rule, greases usually contain one of three base oils; mineral, synthetic or vegetable. Synthetic oils are considered to offer the best overall results, however it's worth considering whether mineral or vegetable based greases may be more appropriate for your specific application.
  • Viscosity: Highly viscous greases provide better stability when exposed to heavy, slow loads. Low viscosity greases work better for lighter and faster loads. Consider the level of viscosity needed for your grease before purchasing.
  • NGLI Rating: The NGLI rating of a grease determines the greases consistency. Ranging from 000 (fluid) to 6 (hard). The consistency you need will vary on the application.

By carefully evaluating these factors, you can select an grease that best suits your needs.

Top Grease Brands

Fuchs
New Tech Lubes
Rocol
Solent Lubricants

Top Greases

Greases FAQs

What are the three types of lubricating greases?

There are three different types of lubricating greases, boundary, mixed and full film.

  • Boundary Lubrication: Boundary lubrication is used in operations where there starts and stops, and where shock-loading is a common phenomenon. It occurs when the two surfaces are in contact that only the lubricating layer is protecting them.
  • Mixed Lubrication: Mixed lubrication is a combination of boundary and hydrodynamic lubrication. Whilst the lubrication layer offers protection their contact with each surface. Additives, again make a difference in this type of lubrication.
  • Full Film Lubrication: Full-film lubrication occurs when the two contacts are separated by the lubricant (fluid or film) and prevents irregularities (asperities) from contact when applied correctly. This is the most sought after form of lubrication.
What happens if you mix greases?

The results depend on whether the two greases are compatible or not. If the greases being mixed are not compatible the effect can be less than favourable, with separations and a generally messy situation.

If you need advice about grease compatibility it's best to seek the advice. You can contact our Technical Safety Team here.

What is the NLGI Rating?

NLGI stands for the National Lubricating Grease Institute, who outlined the standard classification for the measure of relative hardness of a grease in a lubricating application. In short, the NLGI is system of rating a greases consistency from 000 (fluid) to 6 (very hard).

What does dropping point mean in relation to greases?

Dropping point is the term used to refer to the temperature at which a grease becomes fluid enough to drip.

Greases Useful Resources

To ensure you have all the necessary information regarding greases including the guidelines and standards around greases as well as information pertaining to the selection of the right grease, we've gathered a selection of resources, to help you on your journey to selecting the most effective grease product for your needs.

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