Detection of rolling element bearing defects by vibration signature analysis: A review

Almost all machines have rotating parts, of which a vital and critical part is the bearing. The life of rotating machines are mainly depended on the working condition of the bearings. Detecting the health of the bearing has an important role in predective maintenance system. Bearing failures leads to safety issues and it negatively affect the working environment, in terms of machine down times, interruption of production, leading to higher manufacturing costs. The vibration signals siganture generated from a rolling element bearing delivers huge amounts of information about its structural dynamics and working conditions. The basic principle behind the vibration analysis is, the fact that any defect in a bearing gives rise to some vibration. This vibration consists of certain frequencies depending on the nature and location of the defect. The important measurement parameters of vibration are displacement, velocity and acceleration. On the basis of vibration analysis it is possible to detect and locate even very small bearing faults like false brinelling, minute wear marks etc. The vibration signal from a good bearing is compared with the vibration signal from a faulty bearing, the vibration signature generated from a defective bearing differs from the normal state vibration signature and it is determined through the shape of time domain signal peaks, the randomness of peak position and also through frequency domain characteristics.