Early Detection of Industrial-Scale Gear Tooth Surface Pitting Using Vibration Analysis

Ball mill is an essential crusher equipment type mainly used in manufacturing processes of raw materials and processing industries and mines. It consists of a transmission system containing two large-sized helical gears. This study was designed to detect early gear tooth surface fault and pitting on an industrial scale. Condition indicators including RMS, FM4 and NA4 (see "Appendix A" for Definition) were estimated using data obtained from ball mill vibration analysis. Statistical and visual results were compared, aiming to find the best indicator for pitting detection. The results indicated that the NA4, FM4 and RMS indicators are not able to detect initial gear tooth surface pitting independently on an industrial scale. The NA4 was selected as the best indicator. The frequency spectrum was then divided into six frequency ranges. The second gear mesh harmonic range was selected as the best region for detecting early gear surface pitting, and a modified NA4 was considered as the best indicator for detecting gear tooth surface pitting. The results of the visual analysis confirmed the accuracy and efficacy of this technique in providing a new indicator for the machines' working condition monitoring.