Grease can be defined as a petroleum based product with a combination of soap or soap mixtures which may or may not be without fillers.
Oxidation.
Simply put, oxidation is the process of gaining or losing oxygen through movement of electrons.Grease is not a medium that conducts heat easily, therefore oxidation is pronounced at high temperatures.At a certain temperature the grease will fully melt and the gel type structure it has will break down. This is called the drop point. Once this is reached, the composition of the grease changes and something called carbonisation occurs – the effect being that when the grease re-cools its performance is impaired as the structure never fully returns to optimisation.
The point about all this is that for the different types of grease at least of the substances associated will exceed the drop point. Therefore when it comes determining the different types of grease and their uses, the temperature, drop point, oxidation and solidification are all factors needed to be considered.
Properties of grease (generalised.)
Grease is generally comprised of base ingredients and these are:
* Thickener,
* Base Oil and,
* Additives.
The thickener is one of the most important parts as it determines the type of grease that will be produced.
Thickeners can either be soap or non-soap based. Most of the world’s greases are soap based which are derived from different chemical compositions and structures such as lithium hydroxide.
Different types of greases.
Commodity
These are the most common types of grease since they are uncomplicated mixtures that can be mass produced at high yield for competitive cost. Their base is often in lithium, calcium or sodium soaps. Today ‘common’ grease is becoming such a lucrative and sought after ingredient that theft and crime associated with it are on the rise for wider scale application.
High performance greases
These types of greases are much more complex than the basic ones because the soap mixtures used are more specialised, thus they tend to meet the needs of more demanding uses better. High performance greases are usually synthesised by using synthetic based oils.
Although production is less common than commodity greases, while we live in green, high demand and high achieving times, the need for these greases is actually increasing and to be encouraged.
Speciality greases
As the name suggests, these are made and used to suit and meet a specific need. The performance requirements of speciality greases tend to be very high to match precise application requirements. For example the greases can be loaded with ‘performance enhancers’ that are designed to withstand extremes of temperature, oxidation etc.
These greases tend to be expensive and in low production due to their tailored nature. However sometimes only the best will do and speciality greases certainly cover this scope.
