¿Cuáles son los tipos de estrategias de mantenimiento?

A typical industrial facility will be home to many different types of equipment and machinery. With these assets taking up a significant portion of the company budget, it only makes sense to provide them with the proper care and upkeep. However, selecting a perfect fit can seem challenging because of the many different approaches available. Here is a comprehensive list of types of maintenance strategies to get you started on choosing the most appropriate choice.

What Is Maintenance?

Before diving into the details, it would be helpful to first come to a common understanding of the definition of the term. Maintenance generally refers to tasks that aim to preserve the condition of the equipment. Throughout this article, and according to common industrial practice, we will be referring to the preservation of assets using strategies relating to plant maintenance.

Servicing equipment ultimately aims to reduce breakdowns and promote overall reliability. These objectives manifest in daily operations through increasing equipment uptime and availability. Longer-term effects are also achievable through maximizing the potential life cycles of assets. So while any equipment will eventually give way to wear and tear, the next best thing is getting sound returns during its life span.

The overall concept of an effective maintenance strategy seems straightforward. However, due to the many tasks that fall under it, such as inspections, restorations, and replacements, identifying the need for servicing can be tricky. The good news is that several strategies have emerged throughout the decades of collective industry experience. The following sections provide an overview of the many available approaches to maintenance.

Breakdown Maintenance

As the name suggests, breakdown maintenance is a reactive approach to an event concerning the failure of a piece of equipment. Possibly the most intuitive of all the strategies, breakdown maintenance has the simple goal of fixing a broken part.

While this may not sound like a strategy for any circumstance, there are two main reasons a facility might need to perform breakdown maintenance. The first is to service equipment from an unplanned breakdown. The other is purposely running a part until it fails.

Unplanned breakdown maintenance is a reaction to an unexpected event. As you can imagine, this is potentially a significant cause of lost productivity, estimated to cost manufacturers up to $50 billion annually. Depending on the equipment concerned, the impact of a breakdown can range anywhere from a brief pause to a complete operational stoppage for extended periods. Safety risks are also a primary concern, especially for industries that deal with hazardous materials and environments.

On the other hand, purposely anticipating a component to run until it fails usually poses minimal risk. Typical examples of such equipment include disposable parts, easy-to-replace consumables, and even particular assets that are not economical to repair. 

Corrective Maintenance

You can think of corrective maintenance as an extension of the interpretation of breakdown maintenance. While there is still a reactive sense to applying a remediating action, the intent is not to end up with the total failure of a component. Instead of a breakdown event, corrective maintenance more likely results from the findings of an unrelated inspection or any other concerning observation.

Though a step in the right direction in getting ahead of an incident, a corrective action typically does not arise by itself. In other words, it is not a proactive activity. For example, if a technician performing repairs under a different work order noticed something else to be off, it could be an opportunity for corrective maintenance. Depending on the needed fix, the technician could implement a solution at once or trigger a dedicated work order.

Preventive Maintenance

Because of substantial losses to production due to unplanned breakdowns, a more proactive approach to identifying the need for servicing is becoming the standard for most plants. Preventive maintenance (PM) is a broad term that describes the many activities aiming to service a piece of equipment before any deterioration occurs. It includes routine cleaning, repairs, replacements, and inspections.

A crucial element of executing a PM strategy is identifying appropriate criteria for when a maintenance task is required. Two main ways to do this define the most common types of PM.

Calendar-based maintenance is a straightforward type of PM that sets up activities based on a predetermined recurring schedule. Typical calendar-based or time-based intervals may be monthly, quarterly, or annually. Performing routine daily or weekly inspections is a practical example of a time-based activity.

Usage-based maintenance is also easily implemented, except it almost always involves the need for some measuring implement. A certain number of cycles or reading intervals will initiate the need for a PM activity. Car maintenance tasks, such as changing the oil after every few thousand miles, are an everyday example of usage-based maintenance.

While a PM strategy is significantly better than a reactive approach in preempting breakdowns, there is always a possibility of doing too much. By relying on a fixed schedule, regardless of the actual condition of a machine, PM tasks have a lot of room for improvement for optimization.

Predictive Maintenance

Preferring a proactive approach to maintaining equipment, but with a more purposeful process of initiating tasks, leads to predictive maintenance (PdM). PdM is a relatively newer, more advanced approach that picks up certain equipment conditions to predict the timely execution of servicing tasks.

Of course, while the process seems like intuition, it is really building upon comprehensive data-gathering in the background. PdM utilizes sensors and measuring devices that collect and transmit data into a central processing location.

Examples of the processes within a PdM strategy include vibration analysis and infrared analysis, among other practices. Detecting unusual vibration patterns, typically for rotating equipment like bearings, can inform technicians of a potential misalignment or impending deterioration. Infrared analysis looks at distinctive regions of increased temperature readings that could then suggest stress on components. These techniques, and many similar tools, do not necessarily indicate worn-out equipment. Instead, they offer insights about the need for maintenance activity or further inspection.

Because PdM relies on the close monitoring of equipment conditions rather than simply following a preset schedule, companies have the opportunity to focus on value-added tasks. While initial costs go into additional measuring tools and sensor devices, realizing returns from increased reliability and reduced redundant work bear significant potential.

Prescriptive Maintenance

With the rise of the Internet of Things (IoT) comes the emergence of unprecedented industrial practices. Prescriptive maintenance is an example of how modern technological innovations are finding applications in the maintenance space. It combines the approach of a predictive strategy with the computing power of advanced analytics.

You will typically find a lot of similarities between a predictive and prescriptive approach. A lot of the same measuring implements appear in both strategies. The installation of sensors enables the collection of real-time data that then lends itself to advanced analytics techniques. Machine learning and artificial intelligence (AI) draw out the true potential of the available data. Beyond merely analyzing historical patterns, these intelligent platforms can peek into the future and anticipate what is likely to come next and when.

The differentiator of a prescriptive strategy is its ability to go beyond predicting potential failure modes. More than simply describing an impending failure event, it also offers recommendations for the most appropriate countermeasure. So while a predictive approach lets you know a rotational component is stretching its operational limits, a prescriptive strategy tells you the best course of action. You might resort to tweaking speed settings and operation cycles or improving lubrication schedules. Additionally, an effective prescriptive program can approximate the corresponding effects of each countermeasure. Applying a particular recommendation, for instance, might result in twice the life expectancy of a component.

As with any advanced solution, there will be associated costs with choosing a prescriptive approach. The infrastructure to measure, transmit, and analyze real-time data will incur additional expenses. It then comes down to purposeful prioritization and evaluation of which types of assets can realize returns from such investments.

Reliability-Centered Maintenance

Limited resources often prevent facilities from performing the maximum possible service level for assets. But another reason for underachieving targets is when teams assume a single strategy across all plant assets. Reliability-centered maintenance (RCM) overcomes this hurdle by acknowledging the prospect that each piece of equipment may call for a specific and targeted approach.

RCM comprehensively evaluates all viable options to arrive at the most optimal route. Critical components will typically employ more robust strategies to ensure reliability. Types of equipment with a less significant operational impact can take a more reactive approach. The broader picture will present a holistic system of assigning strategies that minimize risk and reduce costs.

The success of an RCM program relies on the criteria that evaluate where it makes the most sense to invest resources. The analysis will look into failure modes, contributions to productivity, and the anticipated failure patterns. Typical concerns to address include events that might cause failure, the probability of a breakdown, the cost of preventive actions, and the impact of a failure event.

Based on the evaluation, engineering and maintenance teams would come together to find an optimal solution. Non-critical items generally assume a more reactive form of maintenance, while crucial assets employ proactive strategies. The precision and extent of resources to implement specialized strategies follow the same decision process.

How Do You Choose a Maintenance Strategy?

Choosing a maintenance strategy is a business decision that weighs the benefits of a selection against its costs. When in doubt about where to start, it is always a good idea to go back to what the data tells you. Methods that provide a framework for such quantitative techniques for prioritization are available.

For example, a criticality assessment is a valuable tool to qualify the criteria that describes the severity of having a piece of equipment out of service. There are several categories to which this kind of analysis applies. Safety is usually at the forefront of the assessment. The highest level of severity, for instance, would apply to a machine that can cause disastrous outcomes of injuries, fatalities, or destruction. The quantitative impacts associated with production and maintenance costs are also usual categories to evaluate. The expenses to repair damage or the resulting loss in production equates to an appropriate severity rating.

According to the severity across several categories, maintenance teams can assess the proportion of resources that makes sense to spend on each asset. Critical equipment and its effects on safety, maintenance, and production justify more costly strategies such as a prescriptive or predictive approach. Machines crucial to daily plant activities, but do not have the same level of impact, may employ a more condition-based or preventive maintenance approach. Lastly, lower-value materials, including consumables, are more practically managed using a reactive or breakdown strategy.

Conclusion

An industrial facility will have several pieces of equipment with varying sizes, complexities, and roles in the production process. Due to the range of applications of these machines, it is often an intimidating task to perform maintenance effectively while also being cost-efficient. Fortunately, a broad range of alternatives is continually evolving to provide the level of service an asset requires. While a seemingly challenging task, companies have an arsenal of strategies that can cater to their needs.