How to correctly select various greases 0

2022-08-02
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How to correctly select various greases

1) soap based grease

soap based grease accounts for about 90% of the output of grease. Most widely used. The most commonly used greases are calcium base, sodium base, lithium base calcium sodium base, composite calcium base and other greases. Composite aluminum base grease and composite lithium base grease also account for a certain proportion. These two greases are promising varieties

(1) calcium base grease. It is a medium viscosity petroleum lubricating oil thickened with calcium soap generated by the reaction of natural fat or synthetic fatty acid with calcium hydroxide

the dropping point is between 75 ~ 100 ℃, and its service temperature shall not exceed 60 ℃. If this temperature is exceeded, the lubricating grease will become soft or even the structure will be damaged, so the lubrication cannot be guaranteed

it has good water resistance, is not easy to emulsify and deteriorate in case of water, and is suitable for lubrication of various mechanical parts in wet environment or in contact with water

has short fiber structure, good shear stability and thixotropic stability, so it has good lubrication and protection performance

(2) sodium base grease is made of natural or synthetic fatty acid sodium soap thickened medium viscosity petroleum lubricating oil

it has long fiber structure and good drawing performance, and can be used on rolling or sliding bearings with large vibration and high temperature. Especially suitable for low-speed, high load machinery lubrication. Because of its high drop point, it can work for a long time at 80% or above this temperature

sodium based grease can absorb water vapor and delay the penetration of water vapor to the metal surface. Therefore, it has a certain degree of protection

(3) calcium sodium base grease. It has the characteristics of calcium base and sodium base grease

it has the water resistance of calcium base grease and the temperature resistance of sodium base grease. The dropping point is about 120 ℃ and the service temperature range is 90 ~ 100 ℃

it has good mechanical safety and pump delivery, and can be used on rolling bearings under less humid conditions

the most commonly used are bearing grease and calender grease, which can be used to lubricate the rolling bearings of medium load motors, blowers, automobile chassis, wheel hubs and other parts

(4) lithium grease. It is made from natural fatty acid (stearic acid or 12 hydroxystearic acid) lithium soap thickened petroleum lubricating oil or synthetic lubricating oil. It is called synthetic lithium base grease, which is made by thickening petroleum lubricating oil with synthetic fatty acid lithium soap

lithium grease is widely used for bearing lubrication of aircraft, automobiles, machine tools and various mechanical equipment because of its various excellent properties. The dropping point is higher than 180 ℃, and it can be used at about 120 ℃ for a long time. With good mechanical stability, chemical stability and low temperature, it can be used in high-speed mechanical bearings. It has excellent water resistance and can be used on wet and water-contact mechanical parts. Lithium soap has strong thickening ability. After adding extreme pressure, anti rust and other additives to the grease, it can be made into a multi-purpose long-life grease, which has a wide range of applications

(5) compound calcium base grease. It is made of medium viscosity petroleum lubricating oil or synthetic lubricating oil thickened with compound calcium soap made of fatty acid calcium soap and low molecular acid calcium salt. Good temperature resistance, the dropping point of lubricating grease is higher than 180 ℃, and the service temperature can be about 150 ℃

it has good water resistance, mechanical stability and colloidal stability. It has good extreme pressure and is suitable for lubrication of mechanical bearings with high temperature and load. The surface of complex calcium base grease is easy to absorb water and harden, which affects its service performance

(6) composite aluminum base grease

it is made of petroleum lubricating oil with different viscosities thickened with composite aluminum soap of stearic acid and low molecular organic acid (such as benzoic acid). It is suitable for the lubrication of various motors, transportation, iron and steel enterprises and other industrial machinery and equipment. Only short fiber structure, good mechanical stability and pumping performance. Because of its good liquidity. Suitable for centralized lubrication system. It has good water resistance and can be used for mechanical lubrication in the presence of moisture or water

(7) compound lithium grease. It is co crystallization of two or more compounds of fatty acid lithium soap and low molecular acid lithium salt (such as azelaic acid, sebacic acid, salicylic acid and borate). It is made of thickened petroleum lubricants with different viscosities, and is widely used in rolling mill furnace front roller bearings, automobile wheel bearings, heavy machinery, various high Ju anti-wear bearings, gear, turbine, worm and other lubrication. High drop point and high temperature resistance; The composite soap has high fiber structure strength, good mechanical stability at high temperature and long service life; It has good water spray resistance and is suitable for lubrication of machinery working in humid environment, such as steel rolling machinery

2) inorganic grease

mainly includes bentonite grease and silicone grease. The lubricating grease made of surface modified silicone thickened methyl silicone oil can be used for electrical insulation and vacuum sealing. Bentonite grease is made of petroleum lubricating oil or synthetic lubricating oil with different viscosities thickened by organic bentonite treated with surfactants (such as dimethyl octadecyl benzyl ammonium chloride or amino amide). It is suitable for the lubrication of automobile chassis, wheel bearings and bearings at high temperature. It has the following characteristics

bentonite grease has no dropping point. Its temperature resistance depends on the high temperature performance of surfactant and base oil, and its low temperature performance depends on the type of base oil selected. The amount of thickener also has an effect on the low temperature properties of the grease

has good colloidal stability, and the mechanical stability of lubricating grease varies with the type of surfactant

slightly poor corrosion resistance to metal surface. Therefore, anti rust agent should be added to the grease to improve this performance

3) organic grease

various organic compound thickened petroleum lubricating oils or synthetic lubricating oils have different characteristics. Most of these greases are used for special purposes. For example, the high-temperature lubricating grease made of synthetic lubricating oil thickened with yindanlin and phthalocyanine can be used at 200 ~ 250 ℃; Fluorinated thickened grease, such as polytetrafluoroethylene thickened fluorocarbon compound or perfluoroether, can resist strong oxidation and serve as lubrication for special parts. For example, polyurea grease can be used for bearing lubrication under radiation resistant conditions

polyurea lubricating grease is made of petroleum lubricating oil thickened by polyurea thickener or synthetic lubricating oil. It has good high temperature resistance. The consistency of grease changes little in the wide temperature range of 25 ~ 225 ℃. Because the thickener molecules do not contain metal ions, the catalytic effect of metals on the lubricating oil at high temperature is eliminated, so the oxidation stability is good; Under the condition of 149 ℃, 10.000r/min, the service life of the bearing is more than 4000 hours. Polyurea grease is a widely used product developed rapidly in recent ten years. It is used for lubrication of high cleaning parts in iron and steel industry, food industry, power and electronic industry, and lubrication of long-life sealed bearings

selection of lubricating grease for construction machinery

in the environment of strong chemical medium, synthetic oil lubricating grease with chemical resistance such as Fluorocarbon Lubricating grease should be selected

(1) the selected lubricating grease should adapt to the grease supply mode of the friction pair. Although it is complex, you do not know that

is centralized? When supplying grease, select 00 ~ 1 lubricating grease; No. 1 ~ 3 lubricating grease shall be selected for regularly greased parts such as grease gun and grease cup; No. 2 or no. 3 lubricating grease shall be used for parts that are used for a long time without changing grease

(2) the selected lubricating grease shall adapt to the working state of the friction pair.

for example, when the vibration is large, the grease with high viscosity, good adhesion and vibration reduction shall be applied, such as the composite soap base grease thickened by high viscosity naphthenic base or mixed base lubricating oil

(3) the selected grease shall be suitable for its purpose of use

the grease for lubrication shall be specifically selected according to the type, working condition, working state, environmental conditions and grease supply mode of the friction pair; For the grease used for protection, it shall effectively protect the metal from corrosion. For example, to protect the parts in contact with seawater and water, aluminum grease with strong adhesion and water resistance shall be selected; The general protective grease can be selected from the simple toy solid hydrocarbon thickened high viscosity base oil used in ordinary work. For sealing grease, pay attention to its resistance to the solvent of the sealed medium

(4) the selected lubricating grease should try to reduce the variety of grease and improve economic benefits

on the condition that the requirements are met, lithium grease, composite soap grease, polyurea grease and other multipurpose greases shall be selected as far as possible. In this way, the variety of grease is reduced, the management of grease is simplified, and the grease cost and maintenance cost can be reduced due to the long service life of multi effect grease

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