It is sometimes interesting to reflect on our own exposure to maintenance when it is overlaid with current thinking and methodologies for best practice maintenance.
In the 1990’s, off highway dump trucks were serviced every 250 hours. This would involve bringing the truck into the workshop for about a shift. We would change the engine oil and carry out other OEM recommended tasks. On top of this we would have carried out a host of other inspections and checks. These would cover everything from hose inspections and electrical checks to our own bespoke checks that had been implemented over a period of time.
Fast forward to the current day and we service our trucks at 500 hour intervals. This has been facilitated by the extension of the oil change interval from 250 hours to 500 hours. So now, instead of the trucks coming into the workshop every 250 hours for a service and the associated inspection, they come in every 500 hours.
So, what has happened to all the inspections and maintenance tasks that were being carried out every 250 hours in the 1990’s? How have we saved a shift of downtime every 250 operating hours? Did we not need to be doing all those checks every 250 hours? In a crude sense, what most of us did was implement the results of a PMO study without realising it.
What is PMO?
PMO refers to Preventative Maintenance Optimisation. Very simplistically, it takes the current PM tasks, considers what the PM tasks are addressing and reviews the in-service failures that are being experienced. It then considers hidden failures and failure consequences and then looks at what can be done to predict or prevent a failure. This effectively ensures that you are doing you PM tasks for a reason.
Back to our example. It seems that we did not really need to be doing most of those PM tasks on a 250-hour service. I say most, since there may be some checks that are still required for business reasons (safety, legal etc.). We may have transferred those inspections from being done in the workshop to being done more efficiently in the field. But in a nutshell, we were able to reduce the amount of downtime associated with the maintenance on a dump truck over its life.
Do I have too many PM tasks?
The PM tasks can originate from many sources and they may not all be relevant. They may exist due to a manufacturer’s recommendation. Bear in mind that manufacturers do not know what your operating conditions are like. The PM tasks recommended by the manufacturer will most likely not have been developed with your own specific operating conditions in mind. You should review the OEM recommendations and consider your own operating and maintenance experience to determine whether the PM task or PM task interval is relevant to your operation.
Another source of PM tasks may be the warranty requirements of the manufacturers. Check if your equipment is still in warranty and whether these tasks are still relevant.
There may be other PM tasks that have been included due to past incidents. Ask yourself whether the task is valid. Sometime the knee-jerk reaction to a failure is to is to add a PM task to prevent the same incident from occurring again, but this task may not address the actual cause of the failure, and therefore may be ineffective.
The PM tasks may have been created by copying them from a similar asset. They may not have been reviewed for the specific asset that it is applied to.
Have things changed?
Having established that the origins of the PM tasks may be flawed, other things may have occurred which could have led to PMs being irrelevant. As examples:
- Equipment may have been modified and the PM tasks may no longer be required.
- Operating parameters may have changed.
- Replacement parts may have changed that have different failure modes or a different service life.
- There may be a duplication of tasks that have crept in over time.
What does it mean for me?
Understanding that your list of PM tasks may not be optimised for your application provides an opportunity for cost reduction. In addition to this, there will be an opportunity to reduce the risk of unplanned failures, and the opportunity to reduce your downtime. Review your Preventative Maintenance tasks. Commission a PMO process for your plant and equipment. You may be surprised at just how much maintenance you don’t really need to be doing.
We offer training, facilitation and consulting assistance in PM Optimisation (PMO) in order to assist our clients to maximise equipment uptime and reduce maintenance costs.
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