The real beauty of the algorithm is that it forces you to think very hard as to whether a strategy is both applicable, or able to be applied, and effective, or that it will make things better than not doing it. (In layman's terms)
It is never so relevant than when you look at the strategies that have been concocted using methods or approaches that do not rely on a decision diagram of some fashion.
First, they almost always jump to design as the first option. This grates on my nerves for several reasons. But most often it is because at best it is destined to sit in some management of change list while committee after committee paw over it trying to work out if it is really worth doing or not.
The time to implementation is only one of the issues with the stock redesign option. other problems include:
- Changes to asset configuration that will need a change in maintenance strategy. But often this is a spreadsheet task done as an afterthought.
- It may introduce additional unplanned for maintenance failures and costs, and
- It may not just correct an existing problem, but move the problem to other areas within an integrated system
Second, you often see tasks that are not applicable and cannot possibly do anything to manage the consequences of failure. I have a case study in the courses I run related to this issue.
Without a decision diagram people are not challenged.
So they continue to impose time based maintenance, but under the guise of condition based maintenance. This can generally be seen by inspections designed to detect the onset of failure, (that is what you are looking for) but done at an interval that has nothing to do with the P-F interval.
So they continue to impose time based maintenance, but under the guise of condition based maintenance. This can generally be seen by inspections designed to detect the onset of failure, (that is what you are looking for) but done at an interval that has nothing to do with the P-F interval.
A situation where any effectiveness of the task would occur by sheer luck as opposed to careful management.
Third, and equally important, is when tasks are applied that are not effective. For instance, regular daily inspections across assets where there is little value in doing them. This could be because there actually isn't ANY likelihood at all of the failure mode developing within one day (applicable) or more likely because they consequences of failure are less than the costs of actually doing the work.
The worst type of ineffective maintenance is the dangerous one. The one where we break into assets to try to detect the onset of failure, or for a preventive routine of some form, and we actually increase the likelihood of something going horribly wrong.
Don't get me wrong. I DO agree with most methods that are used within the maintenance field. Just each one should be used in it's place, or by people who are exceptionally experienced with applicable and affective maintenance strategies. (Not just experienced with maintenance)
For example, Weibull analysis is an exceptionally powerful investigative technique. But without any guidance as when determining the failure management strategy the chance of getting it wrong goes up considerably.
FMEA - great for identifying reasonably likely failure modes, but without a decision path after that then again you raise the likelihood of getting it wrong.
FMECA, again - brilliant not only for determining failure modes, but also for sifting through them and working out which one's are the most important. (The decision diagram does this also by the way... a theme for another post)
But at the end of the day an important failure mode, or a more important one still need to be managed in a way that is both applicable and effective.
Have a look at some of the stuff in your plant now. Are the failure modes at the right level in the first place? And if they are, then are the strategies that have been put in place both effective AND applicable? (because you can't have one without the other... it just doesn't work that way)