Sensitivity of Acoustic Emission to lubrication on bearing surfaces

Sensitivity of Acoustic Emission to lubrication on bearing surfaces

Bearings are one of the vital parts of machines and their condition is often critical to success of an operation or process. Existence of a film of lubricant such as grease between bearing surfaces has a significant role on machine operation status so that friction and surface wear can be minimized. Contaminated grease or the lack of lubricant may lead to an ineffective bearing operating condition or indeed malfunction of the machinery. Therefore, there is a significant need for reliable and robust condition monitoring (CM) of bearings in order to avoid the unexpected breakdown. Acoustic emission (AE) is one of the most popular CM and fault detection techniques. This article proposes a statistical analysis technique to investigate the sensitivity of seven AE parameters to the existence and lack of lubrication in dry and lubricated bearing. To do so, 32 sets of experiment on each bearing characteristic were arranged in a multi-factorial level, including 8 rotational speeds and 4 radial pressures. Four AE parameters were found sensitive to lack of lubricant in a dry bearing. Influence of radial pressure on AE parameters was negligible in both bearings under investigation