Patent ID: 6885972

Claim:
A method for predicting a life span of a rotary machine used in a manufacturing apparatus, comprising: measuring reference time series data of an acceleration of the rotary machine and evaluation time series data of the acceleration respectively, with a sampling interval of less than a half the reciprocal of an analysis target frequency, wherein the sampling interval is a time between samples within a single sampling sequence, a number of samples being at least four times a numerical value of the analysis target frequency, the rotary machine being a dry used in the manufacturing apparatus; generating reference diagnosis data based on variations in a characteristic corresponding to the analysis target frequency by subjecting the reference time series data to a frequency analysis, the characteristic representing a peak acceleration value; generating evaluation diagnosis data based on variations in a peak value by subjecting the evaluation time series data to the frequency analysis; and forming a Mahalanobis space with the reference diagnosis data obtained from the reference time series data measured at a time that is earlier than the time where the evaluation time series data is measured by a predetermined length of time determined through an empirical rule under the same process conditions as the evaluation time series data, calculating a Mahalanobis distance of the evaluation diagnosis data based on the Mahalanobis space, and determining a time point where the Mahalanobis distance exceeds a threshold value as just before the end of the life span.