Investigation of the influence of oil film thickness on helical gear defect detection using Acoustic Emission

This paper reports an investigation into the use of Acoustic Emission (AE) for monitoring gear teeth defects under varying lubrication regimes in helical gears. The investigation used a back-to-back gearbox test-rig with oil-bath lubrication. Variation in oil film thickness was achieved by decreasing the gear metal temperature with nitrogen gas whilst the gears were in operation. Results demonstrate a clear relationship between AE activity, operating temperature and specific film thickness. In addition, results show that there are lubricating conditions that may prevent AE from identifying the presence of gear defects.