Tham khảo tài liệu 'fag_rolling_bearing_lubrication part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Lubricant Selection Grease Oil Selection of Suitable Oils Both mineral and synthetic oils are generally suitable for the lubrication of rolling bearings. Lubricating oils based on mineral oils are the ones most commonly used today. These mineral oils must at least meet the requirements indicated in DIN 51501. Special oils often synthetic oils are used for extreme operating conditions or special demands on the stability of the oil under aggravating environmental conditions temperature radia tion etc. . Renowned oil manufacturers carry out successful FE8 tests themselves. The major chemico-physical properties of oils and information on their suitability are listed in table 30. The effects of additives are listed in table 29. Of particular importance are the additives for bearing operation in the mixed friction range. Recommended Oil Viscosity The attainable fatigue life and safety against wear increase the better the con tact surfaces are separated by a lubricant film. Since the lubricant film thickness increases with rising oil viscosity an oil with a high operating viscosity should be selected. A very long fatigue life can be reached if the operating viscosity z v vj 3 . 4 see diagrams 5 to 7. High-viscosity oils however also have drawbacks. A higher viscosity means higher lubricant friction at low and normal temperatures supply and drainage of the oil can cause problems oil retention . 30 Properties of various oils Oil type Mineral oil Polyalpha olefin Polyglycol water insoluble Ester Silicone oiol Alkoxy fluoro oil Viscosity at 40 C mm1 2 s 000 Max. temperature C for oil sump lubrication 100 150 150 Max. temperature C for circulating oil lubrication 150 200 200 250 240 Pour point C -202 -402 -40 -602 -602 -302 Flash point C 220 3002 - Evaporation losses moderate low moderate to high low low2 very low2 Resistance to water good good good2 hard to separate .
