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Ratio of PM to CM

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joe.pike
Ratio of PM to CM
I've been working with a group to improve the reliability and uptime of several of their systems. This group had a study completed in December 2015, by a very well-known firm that specializes in consulting, which stated that "Industry norms place the median ratio of preventive maintenance to total maintenance hours at 50-60%". The consultant explained that CM and PM time should be almost equal for an effective organization, and which my client believes to be correct today. The consulting firm quoted "maintenance and Reliability Best Practices", 2nd Ed., by Ramesh Gulati as the source for their information. I do not have a copy of Mr. Gulati's book to review myself and was wondering if anyone can confirm this. I'm always concerned when people use a single line in a reference document to substantiate their findings as the context of that quote can be misrepresented. Also, what is your opinion of the best ratio of PM to CM? I believe uptime is king, and therefore CM should be as low as possible while maintaining productivity and uptime. If I had to put a number to that, I suggest a ratio of 10 to 1 in favour of PM as the best solution. Comments? JP