Rolling element bearing failures in paper mill machines are considered in relation to their critical role in the machine function. The paper discusses these failures according to what becomes damaged and how, and relates them to the vibration spectra and their development over the lives of the bearings. Interpretations of some variations in the vibration signature, i.e. relating vibration amplitude changes and frequency shifts to the deterioration processes involved, are proposed and discussed. The literature was found mainly to confirm this analysis. A new approach to envelope alarming is presented and shown theoretically (logically) to offer later renewal with fewer failures, and therefore lower cost and higher productivity. Deficiencies in data coverage and quality, and the feedback of case study results, are discussed. A model to improve maintenance experience is proposed and discussed. Using vibration to monitor component conditions, the accurate prediction of remaining life requires (a) enough vibration measurements, (b) numerate records of operating conditions, (c) better discrimination between frequencies in the spectrum and (d) correlation of (b) and (c). This is because life prediction depends on the amplitudes of(and) the frequencies generated by the component damage. Much money could be saved because some of the present policies utilize as little as half of the useful life of a bearing.
