It goes without saying that across industries, there are different definitions and different categorizations of maintenance strategies. It is more important to look into what each one of these maintenance strategies entail rather than focusing on who has the right definition. First of all, there are two kinds of maintenance, preventive and corrective maintenance. The aim of the preventive just as the name suggests is to prevent any failure. The ides is not only to preventive but to reduce consequences in case the failure does occur or even to asses risks and reduce them. With corrective ones, you wait until the failure is done and then the maintenance kicks in. This is just to restore the functionality of the equipment.
Now, when it comes to preventive maintenance, the idea is to restore the equipment’s functionality regularly and it doesn’t depend on the condition of the equipment. We have established that the main purpose is to prevent but to also minimize any probability of failure happening. This can be based on time where they are done every week or month. This is not the only way they are done, they can also depend on usage for example number of cycles. There are different types of maintenance that fall into this preventive category.
Time-based maintenance is the first one in this category. Maintenance, in this case, is done at regular intervals like weekly, monthly and so on. The purpose of this kind of maintenance is to prevent any kind of failure. This type is based on the assumption that all failure is age-related. This kind of maintenance does not depend on the condition of the equipment.
The next one in line is failure-finding maintenance. This one is important because it looks out for hidden failures. This one requires regular maintenance because these hidden failures would not be seen otherwise. This will keep you on your toes but you also need to use it with another type of maintenance strategy.
Risk is when you put together the likelihood of failure occurring and the consequences that you would expect. When you are limited in the number of resources, you have to be smart as to how you allocate them. This is why risk-based maintenance focuses on assets with the highest risk.
It would be wrong to assume that all failures are age-related. Failures don’t just happen, you will find that there will be some sort of warning. If you can find some evidence that equipment is showing signs of failure, condition-based maintenance would be the go-to strategy. If it is too late to stop the failure, this type of maintenance will minimize the consequences of the failure.
There are more of the preventive types but there are also corrective ones. This one waits for the failure to happen. This is mostly used when failure is acceptable because the consequences are insignificant. The idea is to restore the asset after it has failed. The two types under this category are deferred corrective maintenance and emergency.