Lubricating oil viscosity parameters - bearing knowledge

A measure of the material flow in friction viscosity, in order to prevent movement between parts contact wear and lubricating oil must have enough viscosity, viscosity values by the rise of temperature. But it is the main technique index sign of the lubricating oil, lubricating oil viscosity shall not be higher than the influence of the degree of engine starting, the vast majority of the lubricating oil viscosity is according to its to brand of, is the main basis that all sorts of equipment choose oil viscosity. Viscosity measurement method of divided into two categories: absolute viscosity and relative viscosity. Absolute viscosity can be divided into dynamic viscosity and kinematic viscosity of two; Relative viscosity kind's viscosity, saybolt said several methods, such as viscosity and viscosity redwood. Our country commonly used kinematic viscosity and dynamic viscosity oil viscosity. The standard method for determination of kinematic viscosity of GB/T 265, namely, a certain volume of liquid under gravity flow through a calibration good glass capillary. The viscometer capillary constant and the flow of time is the product of the kinematic viscosity of liquid temperature. Foreign corresponding standard method for determination of oil viscosity are mainly in the United States ASTM D445, German DIN 51562 and Japan's JIS K2283, etc. Some products, such as hydraulic fluid, automotive gear oil viscosity at low temperature are usually's viscometer method to determine with a cloth. GB/T 11145, such as the United States ASTM D2983 and German DIN 51398 standard method. Excessive use viscosity of lubricating oil will increase the wear and tear of parts, in practice, choosing appropriate viscosity lubricating oil, can ensure the normal order of the mechanical equipment, work reliably. Usually, low speed high load applications, choose larger oil viscosity, to ensure adequate oil film thickness and normal lubrication; The applications of high speed low load and selection of smaller oil viscosity, mechanical equipment to ensure the normal starting and running torque, engine oil viscosity is too large, flows slowly, and slowly, oil pressure is high, but the oil throughput is not much, not added friction surface in time, minimum friction produced under the condition of continuous running. Due to the slow oil circulation, by the number of lubricating oil filter, less difficult to chip will wear off in time at the end of the metal, carbon particles, dust cleaning out from the friction surface. , because of the large oil viscosity in the operation of the machine increases the friction between the friction surface, in order to overcome the friction, which increase more fuel consumption, but also reduces the engine power output. Lubricating oil viscosity, oil circulation speed is slow, the cooling and heat dissipation effect is bad, easy to make the engine is overheating. Small so that under the different operating temperature, the temperature can form the oil film between the movement parts. Therefore, do not use engine oil viscosity is too large, cannot think more the greater the viscosity, the better. In guarantee under the condition of lubrication, according to the temperature range, when used as far as possible choose low viscosity lubricating oil. But has more serious to wearing away, clearance has larger engine, can choose a larger lubricant viscosity appropriately. Viscosity of evaluation quality of lubricating oil is an important physical and chemical performance indicators, for production, transportation and use are of great significance.