Grease is another major category of lubricating products other than lubricants and liquids. It is widely used in engineering machinery in automobiles and high-end manufacturing industries. What ingredients does grease consist of? What kind of performance does it have? What are the classifications and how to choose one? Let’s take a comprehensive look at it today!

What is grease?

Grease is a type of lubricant with non-Newtonian fluid characteristics between semi-fluid and solid, which is obtained by dispersing one or more thickeners in one or more liquid lubricants. The basic characteristics of grease are that it has a certain shape, is easy to adhere, and has lower fluidity than the corresponding base oil.

Basic composition of grease

①Thickener. Thickeners in grease account for2%～35%It is generally dispersed in the liquid lubricant in a colloidal state to form a spatial network structure, or is only dispersed in the base oil in the form of a dispersed phase to adsorb and restrict the flow of the base oil. The choice of thickener directly affects the mechanical stability, high temperature resistance, colloidal stability, water resistance and other properties of the grease.

②Base oil. Base oil accounts for 10% of lubricating grease65%～98%Left and right is the dispersion medium of the thickener. The choice of base oil directly affects the grease's lubricity, evaporation, low temperature properties, and compatibility with sealing materials.

③Additives. Additives in grease account for0～10%It can improve some performance of grease. According to the performance requirements of the grease, additives such as structure improvers, antioxidants, metal passivators, rust inhibitors, extreme pressure agents, oily agents, anti-wear agents, and wire drawing agents can be added.

Main functions of grease

The three basic functions of grease are lubrication, protection and sealing:

① Lubricating effect: Grease has the effect of reducing surface wear of two friction pairs in relative motion.

② Protective effect: Grease can isolate or reduce the contact between the surface of the friction pair or the surface of the object and corrosive substances, and can reduce or slow down the corrosion and damage of the material surface caused by chemical effects, including anti-rust, anti-corrosion and water resistance.

③Sealing effect: Grease can provide sealing effect for the contact surfaces between some parts.

Eight properties of grease

①Cone penetration. An indicator used to measure the hardness and consistency of grease, that is,25At ℃, the standard vertebra is5sThe depth of vertical penetration into the grease is the taper penetration. According to the size of cone penetration, grease can be divided into9level.

②Drop point. One of the parameters that reflects the upper limit of the grease's service temperature, that is, the temperature at which the grease changes from a semi-solid state to a liquid state.

③Evaporation degree. It refers to the proportion of loss caused by evaporation of grease under specified conditions. It is an important factor affecting the service life of grease.

④Low temperature torque. Refers to low temperature (-20℃ below) the degree to which grease blocks the rotation of rolling bearings.

⑤Colloidal stability. Pressure oil separation is used to reflect the colloid stability performance of the grease under normal temperature conditions; high temperature steel mesh oil separation is used to reflect the colloid stability performance of the grease under high temperature conditions. Grease has poor colloid stability, which will cause the grease to lose oil during use and is not suitable for long-term storage.

⑥Oxidation stability. Refers to the ability to resist oxidation during storage and use.

⑦ Mechanical stability. Refers to the ability to resist changes in consistency under mechanical working conditions.

⑧Water resistance and rust resistance. It refers to the ability of grease to protect bearings by not dissolving or being washed away by water in the presence of water or water vapor.

Classification of grease

There are many types of greases with different functions. They are roughly classified as follows according to different classification standards.:

① According to the mechanical components to be lubricated:Bearing grease, gear grease, chain grease, etc.

② According to the industrial sectors that use grease:Automotive grease, railway grease, steel grease, etc.

③According to the temperature used:Low temperature grease, ordinary grease and high temperature grease, etc.

④According to application scope:Multi-purpose fats, specialty fats and general purpose fats.

⑤According to the thickener used:Calcium-based grease, sodium-based grease, aluminum-based grease, calcium-based complex grease, lithium-based grease, aluminum-complex grease, barium-complex grease and lithium-complex grease, Bentonite grease, silicone grease, polyurea grease, etc.

⑥Based on base oil:Mineral and synthetic oils.

⑦According to load-bearing performance:Extreme pressure grease and ordinary grease.

⑧According to consistency(000-6total9levels): 000、00、0、1No. suitable for centralized lubrication and gear lubrication.1、2、3For bearings,4、5、6Brick grease sealing.