Run-to-failure is a maintenance strategy where maintenance is only performed when equipment has failed. Unlike unplanned & reactive maintenance, proper run-to-failure maintenance is a deliberate and considered strategy that is designed to minimize total maintenance costs. In many circumstances run-to-failure is a great maintenance strategy. In others it is terrible. In this blog I’ll look at some of the circumstances where run-to-failure maintenance may be appropriate, and describe some ways that you can make run-to-failure maintenance work using a CMMS.
Reasons for using run-to-failure maintenance
Probability of failure
Some equipment types fail more often with increasing age – this could result from wear and tear. Others fail more often when they are new – this could be due to manufacturing defects or incorrect installation. These different types of equipment failure patterns can be shown graphically.
There are other types of failure patterns too. These were discovered during the investigation that led to the development of Reliability Centered Maintenance (RCM). These are shown below.
Run-to-failure should be considered for those types of equipment where the conditional probability of failure remains low with increasing time. These include equipment items that have failure probability curves like those shown in (b) and (e).
Low equipment criticality
Equipment that has a low criticality could also be considered for run-to-failure maintenance. Your lightbulb on the factory roof, for example, will not cause a threat to life, nor have a significant impact on company profits. This lightbulb could, therefore, be subject to a run-to-failure maintenance regime.
You may have other equipment types that do not have safety or profit implications should they fail. These too, could be candidates for run-to-failure maintenance.
Difficulty in performing preventative maintenance
If preventative maintenance is too difficult to perform, then this too could be a reason to choose a run-to-failure maintenance option. Perhaps the equipment is too difficult to reach because of its height, or perhaps it is in a confined space or at a remote location. These are all reasons why run-to-failure may be considered to be the best maintenance type until easier access the equipment can be designed and installed.
The cost of preventative maintenance
Run-to-failure may be a great option when it is just too expensive to perform preventative maintenance. If your analysis shows that the total cost of doing preventative maintenance is more than the total cost of doing run-to-failure maintenance, then this would be a valid reason to adopt run-to-failure as a strategy.
Before you use cost as a reason for using run-to failure, make sure you include all of your costs in the run-to-failure analysis. Are you including lost production, customer unhappiness, re-work and other indirect costs in your analysis. If not, you should because these can be significant.
Planning for run-to-failure maintenance
Just because run-to-failure may be your desired maintenance strategy for a piece of equipment, this does not change the amount of planning that should be done for its future maintenance. Without planning, your run-to-failure strategy is just unplanned and reactive maintenance.
Just as you plan for scheduled maintenance, you should also plan for run-to-failure maintenance. You should know who will be responsible for the work, what parts they need, and the tasks they need to do to ensure the job is done accurately and efficiently. The only difference between planned scheduled maintenance and planned run-to-failure maintenance should be your knowledge about when the maintenance is going to happen.
If you don’t plan you will need to drop everything else you are doing when failure happens, and then attempt to solve the problem. With planning, you simply execute your plan.
Using your CMMS to plan your run-to-failure maintenance strategy
A great way of capturing and storing your run-to-failure plan is to create a scheduled maintenance template in your CMMS. Then, when maintenance is required, you use the template to quickly generate a work order. Easy.
Run-to-failure is a perfectly valid maintenance strategy. It should not be confused with unplanned and reactive maintenance, however. In a legitimate run-to-failure maintenance strategy the reasons for using it will be justified, and proper planning will have occurred for inevitable equipment failure. But when this planning and decision making has occurred, run-to-failure has the potential to be a money saver, and a useful tool in your maintenance strategy toolkit.