It goes without saying that across industries, there are different definitions and different categorizations of maintenance strategies. The definitions do not matter as much as being right about what each one of them entails. First of all, there are two kinds of maintenance, preventive and corrective maintenance. The main purpose of the preventive types is to prevent any kind of failure. This is why it is done before any failure so as to either prevent it, minimize consequences or even to asses whether there are any risks. On the flipside, corrective maintenance is done after the failure. Because the equipment is already failed, the idea is 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. The objective of this kind of maintenance is to prevent failure or reduce any chances of the equipment failing. The regular intervals can either be weekly, monthly and so forth. This is not the only way they are done, they can also depend on usage for example number of cycles. Preventive maintenance includes a number of strategies.
The most obvious one is time-based maintenance. This is the one that includes regular intervals when the maintenance is done. 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. Here the condition of the equipment is not considered at all, only time matters.
Another one under preventive would be failure-finding maintenance. There are many hidden failures when dealing with different assets, this is the focus of this type of maintenance. The thing is, these failures are hidden and the only way they can be found is if there is regular maintenance. This is important as it will help you prepare but you cannot use it on its own.
Risk is when you put together the likelihood of failure occurring and the consequences that you would expect. Most of the time you have limited resources and you have to allocate them carefully. This is risk-based maintenance and the focus is on assets with the most risks.
One thing to note, there are failures that are not age-related. Failures don’t just happen, you will find that there will be some sort of warning. Condition-based maintenance is the answer if there is evidence that an asset is on the early stages of failure. This might stop the failure or reduce the consequences of failure.
There are a couple more under preventive maintenance but there is corrective maintenance too. This one waits for the failure to happen. This is mostly used when failure is acceptable because the consequences are insignificant. When the asset fails, it is them restored. Deferred corrective maintenance and emergency maintenance are the types in this category.