Determination and characterization of the influence of defects on noise generation for tapered roller bearings and their detectability through different control conditions. Proposal of rejection limits for a manufacturing line

At the present time, the current global market is constantly in demand for higher quality, especially for those moving components, such as bearings, to achieve lower levels of vibration and noise. Numerous scientific studies confirm the direct relationship of the bearing shape (waviness) and other defects with vibration and noise. For this reason, Fersa Bearing started studying the waviness parameter and defects that can induce noise and vibrations. Indeed, one of the most important rolling bearing parameters is the vibration level. Vibration in a rotating rolling bearing is a complex physical phenomenon dependent on the condition of operation. Measurement of vibration level generated by rolling bearing allows the assessment of production quality of new bearings. Vibration level analysis provides information about conditions of rolling bearing and allows to detect potential bearing faults. Some types of defects can be generated during handling and other operations or even be already present on parts coming from suppliers, like plastic deformation, scratch or dirt. While others strictly depend on the production process, such as failure to achieve a good surface finish, assembly of a set of rolling elements with considerable dimensional dispersion, incorrect closure of the cage. Measurement of vibration level of an individual bearing under a certain set of conditions does not necessarily characterize the vibration output under a different set of conditions or when the bearing becomes part of a large assembly, but can be a clue on how silent or noisy the bearing will be and can indicate the quality of the manufacturing process. In this thesis, an experimental investigation has been reported related to the vibration and noise behavior of healthy and defective tapered rolling bearings operating under dynamic axial load. The objective is studying the correlation of different types of defects, both localized and distributed and the correlated produced noise, changing the operational parameters, such as load, velocity, measuring time. In this way will be possible to obtain useful conclusions that improve Fersa’s knowledge regarding the noise generation of defects, to understand which are the best conditions to detect the different types of defects and to identify a proposal for noise limits