With the development to enhance the level of industrialization and the industry, more and more machinery and equipment parts of the lubrication in high temperature environment, with outstanding high temperature performance of grease undoubtedly has important significance for equipment to meet the high temperature lubrication. However, with a grease products according to different principles by different methods of determination of the lubricating grease of high temperature limit value will have very big difference, if in the high temperature value measured behind the principle, only with claims on product of high temperature resistance value and purchasing or make lubrication plan may backfire and the operation of machinery and equipment produced adverse consequences.

Drop point - an old method for evaluating high temperature performance
In the past, claiming that the basis for high temperature grease is usually the "drop". "The drop" on behalf of the is in test grease thickener failure, thickening agent lose the cohesion of the role, can not maintain internal oil temperature. "Drop point" is mainly be used in production quality control system test determine correct increase thickener formation parameters, rather than the performance parameter of lubricating greases. Drop point temperature does not represent the grease resistance to high temperature performance, and people can not be used drop point temperature value minus a numerical method to give high temperature resistance value of grease.

Bearing test - modern assessment methods
Determine a good method for the high temperature performance of lubricating grease is a standard bearing test. This test by improving operation strength to accelerate the aging process of grease to high temperature performance of measuring lubricating grease. Include a thickening agent and base oil oxidation caused by aging, and loss caused by grease condensate and evaporation of base oil. In general, bearing test the dynamic grease determination method can better reflect the true situation in the daily operation of mechanical grease the limiting factor in the high temperature properties of lubricating greases and based on the method for the determination of the maximum temperature than that of the substrate in the drop point obtained numerical more true and reliable.

L50 life there are many different types of bearing test method can be used to evaluate the grease of high temperature limit, these various test methods will use a basic device, that is, the bearing is mounted for testing in five sets are placed in parallel to the same equipment. According to the time of each device on the failure of grease, and the use of Weibull statistics can be 50% of bearing to determine the stop time of normal operation, namely so-called test grease at a given temperature, so that grease in the high temperature limit.

The specific methods of bearing testing of high temperature grease mainly include:
- ASTM D3336 test: the method generally let five 6204 ball bearing at 10000 RPM / min speed after 20 h of continuous operation in accordance with the stop cycle of 4 hours of continuous operation, until the grease appear temperature surge or bearing appear too large torque can determine grease losing efficiency.

- SKF R0F test: in this test, five test device the installation of two 6204 test ball bearings, and let them run continuously. Bearing temperature rose sharply, indicating the failure of grease. The running speed and load of the experimental device can be flexible to change, but typically employ a lighter load and the speed is set to 10000 RPM / min. General according to the L50 life of more than 1000 hours in the highest temperature to determine grease continuous operating temperature limit value.

DIN 51821 (FE9) test
Din 51821 (or Fe9) test: the centripetal 7206B stop push ball bearings, and make it in three standard mode of any a mode operation. A method for injection 2ml grease in the bearing sealing cover, and imposing size 1500N axial load, and then at 6000 RPM / min speed operation, so as to determine the grease of the highest temperature limit. When the bearing torque increase (that is, the device power supply and demand increases), indicating that the grease failure. In the din 51825K grease, grease of high temperature limit is the L50 life reached 100 hours in the highest temperature.

Scientific evaluation of the high temperature performance of grease
After understanding the principle and method of measuring the temperature range of lubricating grease, the enterprise can scientifically evaluate and make more appropriate decisions when selecting high temperature grease products.
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