Basic functions - bearing grease lubrication on the use of knowledge

For grease, in particular, the role of soap grease lubrication mechanism, many scholars conducted a lot of research work, but, so far no unified understanding, remains to be further research to solve in the future. Generally speaking, most scholars believe that soap grease is metal soap and stay in the inside of the soap base oil absorption constitute a system of three dimensional network structure. According to the soap - Concept can be thought of gel particle dispersions, soap grease is a oil as the dispersing medium and the soap - Oil gel particles for the structure of the dispersed phase dispersed system. Therefore, the grease lubrication mechanism has the argument. Used to think that, as a result of the effect of metallic soap or the effect of thickener on base oil to the friction pair of contact surface, base oil by the external force on this side and released for lubrication. This view only see role to play in the real lubricating base oil, only according to the following test results, which USES different bowl of thickening agent the same base oil was prepared by grease, its friction coefficient is the same. Another view, base oil lubrication and thickener. This is according to the grease and separate contrast test result of base oil, and grease lubrication performance and bleaching agent of the relationship between the shear strength. More comprehensive view is that the grease lubrication, is partly due to the effect of base oil, but more importantly depends on pasting agent and base oil after the special combination of the both different butyl base oil and different from the lubrication performance of the thickener. 1) Thixotropic grease has the basic characteristics of thixotropy. When applying an external force, the flow of the grease in gradually become soft, the apparent viscosity decreased, but when at rest, after a period of time ( A very short) Again, the consistency ( Restore) This feature is called thixotropy. Decides the characteristics of grease, it can be at the site of the is not suitable for lubricating oil lubrication, and showed its excellent performance. 2) Viscosity grease usually make a similar viscosity or apparent viscosity, said when, on the viscosity of grease must specify the temperature and shear rate. Similar viscosity index can be used to control the low temperature fluidity and pumping. 3) Strength limit the ultimate strength of the grease is to guide the minimum required sample to flow shear stress, also called ultimate shear stress. Grease ultimate strength is a function of temperature, the higher the temperature of fat, the smaller the ultimate strength, temperature is reduced, the ultimate strength of bigger, it depends on the size of the thickener and the kinds of content, and lipid process conditions also have a certain relationship. 4) Cryogenic liquid measure grease performance at low temperature is one of the important index of low temperature torque, namely at low temperature ( - 20 ° c below) Grease block bearing rotational degree of low speed flows, the low temperature torque of the grease by the starting torque and rotation torque after 60 mm average said. 5) Drop point grease under prescribed conditions known as the lowest temperature reached a certain liquid drop point. The drop point of the grease will help identify types of grease and a rough estimate the highest use temperature of the grease, generally speaking, for fat soap base, its temperature should be lower than 20 ~ 30 ° c drop point drop point is higher, its the better heat resistance. 6) The evaporative (evaporative grease C) Said in the long-term use under condition of high temperature grease, grease oil volatilization, evaporative as small as possible. The evaporative mainly depends on the nature of the lubricating oil and fat fractions. 7) Colloidal stability of colloid stability refers to the grease grease under certain temperature and pressure to maintain stability of colloid structure, prevent lubricating oil from the performance of the precipitation in the grease, oil or grease resistance points. Usually the number of conversion for the mass fraction of the precipitation grease oil. The colloidal stability of the grease reflects the grease in the long-term storage and practical application in oil trend, if the grease colloid stability is poor, in the heat, pressure, under the action of centrifugal force and so on easy to under severe oil, results in the decrease of life quickly, and thick and dry, grease lubrication. 8) Oxidation stability oxidation stability refers to the grease when used in long-term storage or long-term high temperature resistance to heat and oxygen, permanent changes in their ability to maintain its nature will not occur. Due to oxidation, are often free alkali content reduced or free organic acid content increases, drop point drop, dark appearance, appear different smell, consistency, ultimate strength, similar viscosity decreased, generated corrosive product and destroy the material of grease, soap oil separation. In long-term storage of grease, therefore, should be stored in dry and ventilated environment, prevent sun, and shall regularly check free base or free change of the project such as organic acid, corrosion resistance, to ensure its quality and performance