Working principle of similar viscosity of grease and analysis instrument
The similar viscosity of grease refers to that when the shear stress of grease exceeds its strength limit, it will flow, and internal friction will also appear when the grease flows. The internal friction characteristics of grease are characterized by similar viscosity. The viscosity of grease is not exactly the same as that of ordinary liquid. The viscosity of ordinary liquid is a constant at a certain temperature and does not change with the shear speed between liquid layers. Ordinary liquid moves according to Newton's law of fluid flow. The flow of grease does not obey Newton's law of fluid flow, and its viscosity when flowing is not a constant at a certain temperature. It's a variable that varies with the interlaminar shear rate. When the shear speed is small, its viscosity is large: when the shear speed increases, its viscosity is small; At high shear speed, its viscosity is small to a certain extent and remains constant. Similar viscosity of grease is an important basic property of grease.
It has a great relationship with the performance of grease in machinery. When grease is lubricated on bearings and other friction parts, it replaces solid friction between friction surfaces of parts with its internal friction. Therefore, the viscosity of grease has a great impact on the power consumption of machinery using grease. If the similar viscosity of the grease used is larger, it is obvious that the friction loss is also larger. The viscosity of grease changes with shear speed, which makes it suitable for use in machinery with frequent speed changes.
Similar viscosity tester of grease (SH0048) is a special instrument used to detect similar viscosity of grease. In the requirements of bearing grease, similar viscosity tester of low temperature is generally detected. Low temperature is generally required to 40 degrees below zero.