Basic Concept of Grease

(1) What is grease

    The latest definition of NLGI (National Lubricating Grease Institute): Grease is a solid or semi-solid product formed by dispersing one or more thickeners into one (or several) liquid lubricating oils . To improve certain properties, some other components (additives or fillers) are added.

(2) Thixotropy of grease

  When an external force is applied, the grease gradually softens in flow and the apparent viscosity decreases, but once at rest, after a (very short) period of time, the consistency increases (recovers) again, which is the thixotropy of the grease.

This special property of grease determines that it can lubricate parts that are not suitable for lubricating with lubricating oil, and shows its superiority.

The composition of grease

  Greases are composed of base oils, thickeners and additives (including fillers).

  Base oils are liquid lubricants, which are divided into mineral oils and synthetic lubricants.

  Thickeners are solid substances that have a thickening effect.

  Additives are substances added to improve certain properties of grease.

The composition of grease - base oil

1. Mineral oil refers to petroleum lubricating oil.

advantage:

  Good lubricating performance, wide viscosity range, oil of different viscosity is suitable for making grease for different purposes; wide source and low price.

shortcoming:

  High temperature and low temperature cannot be taken into account at the same time, or cannot be adapted to a wide temperature range, and can not meet the requirements of some special conditions such as extremely high temperature, extremely low temperature, high speed, long life, chemical resistance, radiation resistance, etc. A variety of synthetic oils are also required for greases used under these severe conditions.

The composition of grease - base oil

2. Synthetic oil

  Synthetic oil refers to a large class of functional liquids synthesized by various chemical reactions. Different synthetic oils show better advantages than mineral oils in some aspects.

Synthetic oils commonly used in lubricating greases are:

  Synthetic hydrocarbon oils, ester oils, silicone oils, fluorinated oils, and polyether oils, etc.

  A variety of synthetic greases have the advantages of high and low temperature, load capacity, oxidation resistance, medium resistance, suitable for high speed, radiation resistance, etc.

The composition of grease - thickener Classification of thickener

  Hydrocarbon base: such as ceresin, paraffin, petroleum grease, etc.

  Soap base: the largest category at present, including sodium base, calcium base, calcium complex, lithium complex, lithium complex, barium base, aluminum base, aluminum complex, etc.

  Organic: urea compounds, amide compounds, organic dyes, fluorocarbons, etc.

  Inorganic: bentonite, silica gel, nitrogen boride, graphite, etc.