In order to reduce processing time and improve machining accuracy, machine tools bearings should have high rigidity, higher running speed and minimal temperature rise. Also, to prevent environmental pollution, there is an increased demand to reduce lubricant consumption and adoption of grease lubrication. In particular, the most wanted technology in the bearing market is adoption of a grease lubrication system that is eco-friendly and is easy to handle and maintain. A grease lubricated bearing system is required to withstand operation of 20,000 hours without re-lubrication therefore, grease with high durability is needed.
Generally, durability of a given grease is affected by its heat resistance feature (resistance against oxidation-deterioration. Thus, to evaluate their durability the bearings need to be tested by subjecting them to high temperature in excess of 150˚C . However, on machine tool bearings that are used under ordinary-temperature high-speed environment, it has been observed from experience that greases with high-temperature durability do not always achieve longer life. Therefore, greases for actual machine tool bearings have been evaluated and selected through durability tests.
Consequently, for machine tools bearings to efficiently achieve longer life under grease lubrication, we have to (a) define the mechanism that controls grease life under an ordinary-temperature high-speed environment and (b) develop a long-life bearing based on the resultant finding.
This technical paper identifies the various characteristics needed for long-life grease in machine tool bearings, and presents the information about “SE-1” grease that is used on sealed angular contact ball bearings that can operated with dmn=1.7 million.
To know more click on the below link ..