Outer race defect width measurement in taper roller bearing using discrete wavelet transform of vibration signal

Rolling element bearing is one of the important components in rotary machines. Although a significant quantum of work has been done on bearing defect monitoring, estimation of defect size in bearing elements is still a challenge. In this paper, a technique based on decomposition using Symlet wavelet is proposed for measuring outer race defect width of taper roller bearing. Experiments were carried out on a customized test setup. Seeded defects of different size were introduced separately in the form of an axial groove on the outer race of taper roller bearings using laser engraving technique. It is not only difficult but ambiguous to detect the entry point in the groove defect by making use of the signal. The ambiguity gets reduced by using Symlet5 wavelet due to its linear phase nature which maintains sharpness in the signal even when there is a sudden change in signal. The proposed technique has been successfully implemented for measuring defect width over a range of 0.5776–1.9614 mm. The resulting measure of defect width has been also verified using image analysis. Maximum deviation in result has been found to be 4.06% for the defect width of 1.1820 mm at no load which was found further reduced to 1.02% with increase in load.