Grease is made of three main components; a base oil, thickener and additives. Oil, or base oil, is the main component in the formulation (75 -85%) followed by the additives (10-15%) which is all held together by the thickener. The thickener is also referred to as the “sponge” as it soaks up the base oil and additives to later be released under pressure.
Today’s products are, by majority, produced with mineral oil as the fluid component. The mineral oil as a base, characteristically, delivers good performance to most industrial applications. Other than being the main source of lubrication, base oil is also responsible for influencing the pumping and flow-ability.
On the other hand, in extreme temperatures, most equipment require grease that has a synthetic base oil to provide better stability in the given conditions.
The thickener is a material that, in combination with the selected lubricant, will produce the solid to semifluid structure. The primary type of thickener used in current blends is metallic soap.
These soaps include lithium, aluminium, clay, polyurea, sodium and calcium. Lately, complex thickener-type greases are also gaining popularity - they are being selected because of their high dropping points and excellent load-carrying abilities.
Being the back bone of grease, thickener ranges from a simple metal soap or complex, organic and even inorganic gelling agents. The complex products have a combination of conventional metallic soap and a complexing agent. Yet whatever the thickener may consist of, several of the central properties and performance qualities of the formulated grease come from the thickener system.
The thickener is also responsible for controlling the water resistance characteristics. For example, soda-based solutions are poor in water resistance unlike aluminium complex and sulfonated ones as they are well known for their properties in water resistance.
Additives can wear several hats when it comes to the product formulation. Primarily, they are used to enhance the existing required properties to receive the maximum benefit during application.
The base oil in a fully formed solution has certain characteristics as does the thickener. Additives can either bring the desirable properties out or add them while supressing unwanted traits. The most common additives are to aid in anti-rust, oxidation, extreme pressure, antiwear and friction reduction.
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