The key difference between grease and lubricant is that grease is a semi-solid substance that can become liquid upon starting to move, whereas lubricant is already in the liquid state.
Grease and lubricant are two important materials that have everyday use. Lubricants are similar to grease, and both are useful in lubricating systems or tools. Moreover, grease holds solid lubricants in suspension.
CONTENTS
1. Overview and Key Difference
2. What is Grease
3. What is Lubricant
4. Grease vs Lubricant in Tabular Form
5. Summary – Grease vs Lubricant
What is Grease?
Grease is a solid or semi-solid substance that is useful as a lubricant and is formed as a dispersion of thickening agents in a liquid lubricant. Generally, this material contains a soap emulsified with mineral or vegetable oil.
Grease possesses a high initial viscosity that can be dropped to give the effect of an oil-lubricated bearing upon the application of shear. This bearing approximately has the same viscosity as shear thinning. Sometimes, we can use grease to describe lubricating materials that simply occur as soft solids or high viscosity liquids. However, these materials do not tend to exhibit shear thinning properties that are characteristic of classic grease. E.g., petroleum jellies such as Vaseline are not generally classified as grease.
Typically, ideal grease contains an oil and other fluids lubricant that is combined with a thickener such as soap to form a solid or semi-solid. Moreover, greases are shear-thinning or pseudo-plastic fluids. This means the viscosity of the fluid is reduced under shear. When a sufficient force is applied to the grease to shear it, the viscosity tends to drop and achieve the viscosity of the base lubricant, e.g., mineral oil. This sudden dropping in the shear force can cause the grease to be considered a plastic fluid.
What is Lubricant?
A lubricant is a material that is helpful in reducing the friction between surfaces upon their mutual contact. This reduces the generation of heat when these surfaces move. These materials are able to function for transmitting forces, transporting foreign particles, and heating or cooling the surfaces.
There are many different uses of lubricants, which include producing tablets in the pharmaceutical industry, cooking (oils and fats used in frying pans as lubricants, the oil used in baking to prevent sticking), bio-applications on humans such as lubricants for artificial joints, ultrasound examination, medical examination, and sexual intercourse. The general properties of a lubricant include a high boiling point, low freezing point, high viscosity, index, thermal stability, hydraulic stability, demulsibility, corrosion prevention, high resistance, etc.
What is the Difference Between Grease and Lubricant?
Grease and lubricant are important materials that are useful in household needs and automobiles, etc. The key difference between grease and lubricant is that grease is a semi-solid substance that can become liquid upon starting to move, whereas lubricant is already in the liquid state. Moreover, grease comes in tubes or tubs whereas lubricant comes in cans. In addition, grease can be applied through a gun or other tool while lubricant can be sprayed or squirted out through a dropper bottle.
The below infographic presents the differences between grease and lubricant in tabular form for side-by-side comparison.
Summary – Grease vs Lubricant
Grease is a solid or semi-solid substance that is useful as a lubricant and is formed as a dispersion of thickening agents in a liquid lubricant. A lubricant is a material that is helpful in reducing the friction between surfaces upon their mutual contact. The key difference between grease and lubricant is that grease is a semi-solid substance that can become liquid upon starting to move, whereas lubricant is already in the liquid state.
Reference:
1. Wright, Jeremy. “Grease Basics.” Machinery Lubrication, Noria Corporation, 21 June 2019.
Image Courtesy:
1. “Wheel Bearing Grease” By Surv1v4l1st – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “TRP – TRP Lubricant Program” By TruckPR (CC BY-NC-ND 2.0) via Flickr