1. Liquid lubricant:

　　Liquid lubricants are the lubricants with the largest amount and variety, including mineral oils, synthetic oils, animal and vegetable oils, and water-based fluids. Among them, the amount of mineral oil is the largest, accounting for more than 90% of all liquid lubricants.

　　Liquid lubricants have a wide range of viscosity, providing a wide range of choices for friction pairs and moving parts that work under different loads, speeds and temperatures, and are rich in resources, most of which are cheap and easy to obtain. In particular, a certain amount of additives can be added to improve its physical and chemical properties, give new special properties to the lubricating oil, or strengthen some of its original properties to meet higher requirements.

　　Synthetic lubricating oils include many different types, compounds with different chemical structures and different properties, and are mostly used in harsh working conditions, such as extremely high temperature, extremely low temperature, high vacuum, heavy load, high speed, corrosive environment and radiation environment, etc.

　　Water-based fluids are mostly used for metal working fluids and flame-retardant hydraulic media. Commonly used water-based fluids include water, emulsion (water-in-oil or oil-in-water type), water-glycol and other chemical synthetic fluids or semi-synthetic fluids. liquid.

　　Animal and vegetable oils and fats are commonly used in metalworking fluids and flame-retardant hydraulic media, worm gear oils, thread processing oils, etc. In recent years, great progress has been made in the research of biodegradable oil. According to the information, the amount of the flame retardant liquid has increased greatly, and its main characteristics are good oiliness and good biodegradability, which can meet the requirements of environmental protection.

　　The disadvantage is that the oxidation stability, thermal stability and low temperature performance are not ideal.

2. Grease:

　　The amount of lubricating grease is second only to lubricating oil, and it is generally composed of base oil, thickener and additives (or fillers) mixed at high temperature. The main varieties are divided into four categories according to the composition of thickeners: soap-based grease, hydrocarbon-based grease, inorganic grease and organic grease. The lubrication of many friction pairs is inseparable from grease lubrication. Such as most rolling bearings, sliding bearings, gears, springs, winches, wire ropes, skateboards, etc.

　　In addition to anti-friction, anti-friction and lubricating properties, it can also play the role of sealing, vibration reduction, damping, rust prevention, etc. Its lubrication system is simple, easy to maintain and manage, and can save operating costs. The disadvantage is that the fluidity is small, the heat dissipation is poor, and it is easy to produce phase change and decomposition at high temperature.

3、Solid lubricants:

　　Divided into soft metals, metal compounds, inorganic and organic 4 categories. According to its physical form, it can be divided into three types: solid powder, film and self-lubricating composite material. Solid powder can be dispersed in gas, liquid and colloid; thin film can be made by spraying, electrophoretic deposition, sputtering, vacuum deposition, flame spraying, ion spraying, electroplating, sintering, chemical generation, dipping, bonding and other processes. to make. It can adapt to special working conditions such as high temperature, high pressure, low speed, high vacuum and strong radiation. The disadvantage is that the friction factor is large, the cooling and heat dissipation are poor, and the dry film is difficult to replenish during use.

4、Gas lubricants:

　　Gas is also a lubricant. For example, air is easy to use, will not deteriorate, and will not cause pollution to the surrounding environment and supporting elements. The use of gas lubricants to support elements has low friction, a wide operating temperature range, and can maintain a small gap. It is easy to obtain high precision and can work normally in radioactive environments and other special environments. The disadvantage is that there must be a gas source, and clean and dry gas is supplied from the outside; it has higher requirements on the manufacturing precision and material of the support. Commonly used gases are air, hydrogen, oxygen, nitrogen, carbon monoxide, helium, water vapor, etc.