tailieunhanh - Bearing Design in Machinery Episode 1 Part 5

Tham khảo tài liệu 'bearing design in machinery episode 1 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | lubrication conditions. Additional types of antiwear additives are various phosphate compounds organic phosphates and various chlorine compounds. Various antiwear additives are commonly used to reduce the wear rate of sliding as well as rolling-element bearings. The effectiveness of antiwear additives can be measured on various commercial wear-testing machines such as four-ball or pin-on-disk testing machines similar to those for friction testing . The operating conditions must be close to those in the actual operating machinery. The rate of material weight loss is an indication of the wear rate. Standard tests for comparison between various lubricants should operate under conditions described in ASTM G 99-90. We have to keep in mind that laboratory friction-testing machines do not always accurately correlate with the conditions in actual industrial machinery. However it is possible to design experiments that simulate the operating conditions and measure wear rate under situations similar to those in industrial machines. The results are useful in selecting the best lubricant as well as the antifriction additives for minimizing friction and wear for any specific application. Long-term lubricant tests are often conducted on site on operating industrial machines. However such tests are over a long period and the results are not always conclusive because the conditions in practice always vary with time. By means of on-site tests in most cases it is impossible to compare the performance of several lubricants or additives under identical operation conditions. Corrosion Inhibitors Chemical contaminants can be generated in the oil or enter into the lubricant from contaminated environments. Corrosive fluids often penetrate through the seals into the bearing and cause corrosion inside the bearing. This problem is particularly serious in chemical plants where there is a corrosive environment and small amounts of organic or inorganic acids usually contaminate the .