The three types of maintenance: corrective maintenance, preventive maintenance, predictive maintenance. Reactive maintenance, also known as corrective maintenance or fault maintenance; preventive maintenance, which is regular maintenance performed according to defined programs, regardless of the condition of the equipment; predictive maintenance or condition-based maintenance, which is based on constant monitoring of the operating team and predicting the occurrence of faults. The problem is to rely on reactive maintenance of medium or high priority assets. Because preventive measures are not taken in a reactive maintenance strategy, the useful life of the equipment will end up being shorter than with one of the alternative strategies.
However, we should not confuse reactive maintenance with emergency maintenance, which occurs at different stages of a breakdown. While reactive maintenance is carried out at a time when certain physical damage or disturbances in the normal operation of the equipment are noticeable (i.e.,. A functional failure), emergency maintenance occurs after a total equipment failure, requiring urgent maintenance (and generally has higher costs). Preventive maintenance arises in contrast to reactive maintenance.
Rather than waiting for the malfunction to occur, this type of maintenance aims to prevent it from occurring. Preventive maintenance is carried out on a cyclical and scheduled basis, regardless of the state of the asset and in order to avoid breakdowns and minimize the consequences of equipment failures. The maintenance manager defines the frequency based on an estimate of the useful life of the asset and the manufacturer's recommendations. Examples of preventive maintenance actions include periodic reviews, inspections, cleaning and lubrication of parts.
This type of maintenance is vital for high-priority equipment, which is necessary for the normal operation of the company. In fact, the greater the risk associated with a particular malfunction, the greater the need for preventive maintenance to increase asset life and reduce unplanned downtime. A classic example is elevators or freight elevators; an elevator breakdown can be risky if someone is trapped; repair can take a long time and an unserviced elevator is always extremely cumbersome. Because they are not based on the actual condition of the equipment, preventive maintenance plans can sometimes be inefficient and result in unnecessary maintenance (including the replacement of parts) that costs time and money.
Even considering the potential waste of preventive maintenance, these costs tend to be much lower than when repairing an asset, only when there is already a functional failure. Strategies focused on preventive maintenance represent cost savings compared to reactive maintenance. Some estimates point to savings of between 40 and 60% per year when preventive maintenance is the goal. While there is a tendency to confuse reliability-centered maintenance (RCM) with simple preventive maintenance, they are not the same thing.
In short, the goal of RCM is to increase the availability of assets. Obviously, this requires a primary focus on preventive maintenance, but not exclusively. There are several types of maintenance that fit a reliability-focused strategy, including predictive maintenance, which we'll focus on in the following paragraphs. Therefore, although preventive maintenance and RCM overlap, they are not the same thing and should not be used synonymously.
Of all the types of maintenance, this is the most recent and the one that requires the most investment in technology. The purpose of predictive maintenance is to predict when a fault is about to occur. When certain undesirable conditions are detected, a repair is scheduled before the equipment actually malfunctions, eliminating the need for costly reactive maintenance or unnecessary preventive maintenance. Despite the high investment, predictive maintenance can represent big savings in the long term.
Predictive maintenance is more effective in detecting potential faults than preventive maintenance and is more incisive in determining what actions are actually needed. Take a look at our comparative article on these two types of maintenance to better understand the differences between them. Many sources define predictive maintenance as condition-based maintenance. Although, after all, this is a misconception and understandable, predictive maintenance also evaluates the condition of each piece of equipment; we believe that it is important to make this distinction.
Condition-based maintenance focuses on well-defined analysis and parameters. For example, if after a visual inspection we detect something abnormal, we intervene. If the power of the equipment has decreased, then there has been a clear change in the state of the device and we must carry out maintenance. However, predictive maintenance goes a little further by trying to detect faults at an even earlier stage.
Unfortunately, there is no recipe that all companies can follow to obtain the best results, regardless of the type of assets they have to manage. But now that you know the advantages and disadvantages of each, you can start preparing the cocktail that is right for you. In our opinion, the best strategy is to have a plan that incorporates the different types of maintenance, as appropriate for each type of equipment, according to its value and priority, and taking into account the investment possibilities of your company. Unfortunately, books rarely specify this distinction, leading to the mixing of oranges and apples under the same general term of “maintenance tasks”, which is not precise enough to correctly describe other maintenance concepts within preventive maintenance.
Therefore, as a natural evolution of reactive maintenance, the most obvious way to improve your maintenance operation is to implement a preventive maintenance strategy. Reactive maintenance is commonly used to respond to a tenant's request to repair items in their units, and preventive maintenance is used to regularly inspect and replace filters on essential assets, such as an HVAC machine. However, the problem is that most people think of traditional time-based maintenance when they talk about preventive maintenance. This means that you must have a way to track available spare parts, quickly communicate changes in task priority, stay on top of pending maintenance activities, and track essential maintenance KPIs, such as fault metrics.
The opposite of planned maintenance is unplanned maintenance, which has not been properly prepared and is planned according to plan as work is done. This is because this type of maintenance doesn't go through the full maintenance planning process (%26) because it's very urgent and is simply planned on the fly. But, in the minds of many people, fault maintenance is urgent maintenance, maintenance that must be done right now i. When people talk about preventive maintenance (or preventive maintenance), they usually refer to what is best described as time-based maintenance (TBM).
The 6 different types are: predetermined maintenance, preventive maintenance, corrective maintenance, condition-based maintenance, predictive maintenance and reactive maintenance. I prefer to maintain the planned and unplanned distinction for (corrective) maintenance to identify maintenance tasks that have not been planned i. Time-based maintenance is basically a type of maintenance that is performed at regular intervals while the equipment is still operating with the goal of preventing failures or reducing the likelihood of failure. Therefore, in my opinion, planned maintenance is maintenance that has gone through the planning process and is properly prepared with all the steps of work, labor, parts and tools identified and organized.
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