Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/957021
34 | March - April 2018 | www . machinerylubrication.com To ensure the reliable operation of rolling bearings, correct lubrication is a vital and all too often overlooked factor. e main purpose of a lubricant is to separate the metal surfaces of the bearing's components with a thin lubricating film to prevent wear. At the same time, the lubricating film reduces friction and therefore power dissipation, resulting in reduced energy consumption of the whole system. Nearly 40 percent of all premature bearing failures are caused by lubrication problems. e reasons for this are varied, but they often begin with mistakes during installation of the bearings as well as incorrect main- tenance, such as failure to relubricate on time. Some problems can be traced back as far as the design stage of an application, with too little attention paid to the bearing arrangement and lubrication system, as the type of bearing used generally affects the lubrication require- ments. Other criteria for selecting the proper lubricant include the bearing load, operating temperature, ambient temperature of the bearings, bearing speed range and possible contamination of the bearings. In addition to these technical factors, the costs of both the lubricant and the lubrication system must be considered. e effects of lubrication on the performance of a bearing can be seen in the following three examples. Cylindrical Roller Bearings in a Gearbox As part of a theoretical consideration of the bearings in a power take-off gearbox, the lubrication was inves- tigated more closely. It was found that, under the given operating conditions, the lubricant's viscosity was much too low to form a sufficiently effective lubricant film. Increased wear and a reduced service life would have been the logical consequence. erefore, the use of a more viscous or thicker lubricating oil was recommended. To be on the safe side, a practical test was performed in which two identical gearboxes were filled with the lubricating oils to be compared and run for a period of 500 hours. In the subsequent results, discolorations and initial signs of wear were clearly visible on the functional Lubrication's Effects on Rolling Bearing Reliability BEARING LUBRICATION Daniel Stöckl and Klaus Grissenberger | NKE Austria Figure 1. Inner ring of a cylindrical roller bearing after operation with an excessively mobile oil Figure 2. Inner ring of a cylindrical roller bearing after operation with a sufficiently viscous oil Nearly 40 percent of all premature bearing failures are caused by lubrication problems." "