TABLE OF CONTENTS Needless to say, optimizing machinery uptime is a continuous improvement task. This chapter now shows how the leading companies, the Best-of-Class practitioners, try to interrogate their available data in an effort to "predict the future." What at first seems a step up in complexity is not really that difficult and competent teacher-consultants can be enlisted for these analyses.
They are cumulative failures plotted against cumulative time on log-log graphs form Crow/AMSAA reliability growth plots. The plots can handle data from single failure modes or multiple failure modes. Slope of the trend line is an important statistic telling if failures are increasing, decreasing, or the failure rate is unchanged. The method is simple and visual.
The challenge of every reliability engineer is to make reliability improvements to avoid failures. Improvements, with longer times between failures, will put a cusp on the trend lines. The cusp will demonstrate a real change has occurred by substantially stretching the time until the next failure. The longer intervals to the next failure will cause localized trend lines to appear with flatter slopes. When the former trend line is extrapolated to longer times, improvements must demonstrate measurable, vertical gaps which measure the cumulative failures avoided by the improvements. Thus improvements are visual and quantifiable likewise deteriorating conditions produce steep slopes, and situations of no change are identifiable.
The view from your office may be spectacular, but can you see the future failures and...
