The RCM analysis consists of 7 steps. Steps 1-2-3-4 describe the current failure behaviour in a Process FMEA. Steps 5-6-7 use the FMEA to make the right choices to develop a maintenance concept. Steps 1 to 7 are called the RCM Analysis.
A choice is made to analyse a certain process. This can be an asset, but also a part of the production process. System boundaries are drawn and the description of the process / asset is recorded in an Operational Context.
Then the functions are defined that together cover the Operational Context. To complete the list of functions, RCM uses a fixed structure.
This step is very important. It describes the functional failure. This is a condition that does not meet the function. Too often, this step is not properly understood and applied, which has a direct negative effect on the quality of the FMEA and therefore of the maintenance concept.
This step describes the forms of interference. These are the causes of functional failures, including the underlying reasons. These are also called failure mechanisms or root-causes.
It is this step that makes the term FMEA. FM stands for Failure Mode. A cause with a root cause. We often see that there are no failure modes, but failures described. A correct list of all possible failure modes is the heart of every analysis.
Step 4 describes the details of step 3. It describes “What happens when the failure mode occurs”. In some FMEAs, this very important step is limited to a quick enumeration.
The failure effect describes what happens when the failure mode occurs. This starts with all the warnings that indicate that this form of failure mode is under development. The PF intervals are recorded.
In addition, a record is made of what is happening:
– The combination of the burden of proof that only this form of failure mode may have occurred.
– the effects on production, safety, environment, quality, downtime
– how this failure mode is solved
The criteria for maintenance tasks differ as to whether the consequences are only economic, affect safety / health / environment or go unnoticed and increase risks with hidden failures.
For this reason, in the RCM decision tree at step 5, a choice is made as to whether the type of failure (with the failure effect) has consequences that correspond to the categories: Hidden – Safety/Health/Environment – Economic consequences.
In this step if there is a pro-active task that can prevent the failure mode. By this we mean the following task types:
– on-condition task
– discard task
– restoration task
– combination task
If no solution was found in step 6, there is still step 7 which offers options to minimise the consequences. The following task types are then considered:
– failure finding (functional testing)
– mandatory modification
– desirable modification
– corrective task
Once a task type has been worked out for each failure mode, the maintenance concept is complete. This is where RCM stops.
Then the maintenance concept has to be nested and the maintenance program must be updated and, last but not least, the maintenance concept has to be maintained.
This is quite difficult for many. That’s why our training courses make it a lot easier. Check out the training courses here.
