Last Updated: May 11, 2021

What Is Preventive Maintenance?

Preventive maintenance (PM) is a type of proactive maintenance that includes adjustments, cleaning, lubrication, repairs, and parts replacements. PM aims to keep assets in good order and reduces unscheduled downtime and sudden major repairs. On this page, we dive into one of the most popular maintenance strategies used across various industries and applications

The Ultimate Guide to Preventive Maintenance

In this guide, we'll take you through everything you need to know to start or improve a preventive maintenance program at your organization.

Preventive vs. Preventative Maintenance

Preventive has the same meaning as preventative. Both terms are often used interchangeably, which is understandable, given they refer to the same type of program. PM, for short, is used for both as well.

Benefits of a Preventive Maintenance Program

A preventive maintenance program can decrease downtime, increase asset lifetime, and increase the amount of planned maintenance.

Overview

Preventive maintenance is carried out primarily to increase an asset's lifetime by preventing excess depreciation and impairment or untimely breakdowns. This maintenance strategy includes, but is not limited to, adjustments, cleaning, lubrication, repairs, and parts replacements.

Due to the unique needs of different assets, the type and amount of required preventive maintenance vary. Developing a PM program is a balancing act between being proactive but not wasteful. You want your maintenance efforts to prevent a breakdown, but not at the expense of performing too much unnecessary work. Because of this, it can be challenging to establish a successful and cost-effective preventive maintenance plan.

As mentioned in later sections, there are several ways to kick-off a preventive approach. For example, a good rule of thumb is to start with a time-based preventive maintenance program. As you gain more information and have more data to identify the need for tasks, you can then explore more predictive methods.

Types of Preventive Maintenance

Any maintenance that is not reactive is preventive maintenance. Where it becomes more complex and open to interpretation is how to achieve a preventive approach. There are various types of preventive maintenance that may require different sorts of technology and expertise. One of the defining characteristics of a preventive maintenance type is how they assess the need for maintenance.

Four common types of preventive maintenance include:

Calendar-Based Maintenance

This time-based preventive maintenance approach is the most commonly used and the easiest to implement. A recurring work order is scheduled when a specified time interval is reached in the CMMS. Typical examples of time intervals include annually, quarterly, or monthly.

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Usage-Based Maintenance

Instead of relying on time, usage-based maintenance takes a more asset-specific approach. Meter readings are used and logged in the CMMS. When a specific measurement is reached, a work order is created for routine maintenance. Measurement readings might be in units of the number of cycles run, kilometers traveled, or hours of service.

Predictive Maintenance

Predictive maintenance, as the name suggests, tries to look into the future using data from the past. When work order data is logged in the CMMS, Maintenance managers can predict when an asset will crash based on historical events and create specific preventive maintenance tasks to prevent them from happening again. Because this approach requires more information, expect to use additional instruments, equipment, and sensors to capture data.

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Prescriptive Maintenance

Prescriptive maintenance brings in a lot more brainpower on top of the hardware from the previous types of preventive maintenance. This type is similar to predictive maintenance, but instead of only the maintenance manager prescribing preventive maintenance tasks, machine learning software assists them. While prescriptive maintenance can be a sizable investment, it pays off by optimizing your efforts to activities that add value.

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Benefits of Preventive Maintenance

There are more benefits of implementing a preventive maintenance program than merely reducing the amount of unplanned downtime. Other benefits of a preventive maintenance strategy might not be as obvious and intuitive. Here are some more specific benefits of a preventive maintenance strategy.

1. Extension of Asset Lifetime

Equipment, machinery, and generally all physical assets do not live forever. They run the course of their expected useful life. A preventive maintenance strategy maximizes the value of an asset by making sure it gets the proper care to last through its lifetime and beyond.

2. Increased Safety and Reduced Risk of Injury

Perhaps the most significant benefit to employing a preventive maintenance strategy is increased safety. The risk of injury is a real concern, especially in hazardous industries. But really, any company with some form of heavy equipment experiences substantial levels of risk. The price of employee safety is never too high. The way organizations like the Occupational Health and Safety Administration (OHSA) rigorously enforce government policy only reinforces the importance of safety.

3. Optimized Maintenance Planning and Resource Allocation

Preventive maintenance allows you to plan your tasks. By being in control of your schedules, you can arrange for more efficient and effective procedures. Downtime then becomes a strategic decision to perform as much necessary work as possible. Think of how shutdowns work. Imagine how maintenance teams can group tasks to maximize value from planned downtime.

4. Less Expensive Corrective Repairs

Corrective repairs do not come cheap if you are trying to fight massive fires in the least amount of time possible. Consider factors such as production losses, urgent expediting costs, and possibly overtime. By employing a preventive maintenance strategy, you can significantly minimize corrective repairs. If any necessary work comes up, they are likely minor repairs that have far from serious consequences.

5. Better Margins and Profits Due to Less Downtime

Cost advantages are the kind of benefits that are easily appreciated. And this translates to multiple groups within the organization―all the way to top management. By having substantially less downtime, particularly unplanned downtime, value-adding processes can thrive.

When to Use Preventive Maintenance

In the real world, selecting the most suitable maintenance strategy for an asset is not always straightforward. To help teams make an informed decision, it helps to have a good idea of what types of equipment you have and your available options. Knowing how preventive maintenance works, for example, equips you to assess the types of components that can benefit from it. Here are a few factors that can help decide when to use preventive maintenance:

Critical Equipment

Part of the preventive maintenance strategy is keeping a watchful eye on assets. Critical pieces of equipment benefit the most from the way a preventive maintenance strategy manages your equipment. You are not only allowing your machines to last but also ensuring that their performance is optimal.

Preventable Failure Modes

Knowing your equipment can take work. You need reliable data and accurate information. But what you know about your assets can mean the difference between successfully developing a plan or not. For example, by knowing the possible failure modes of a machine, you can identify the paths it may take towards failure. These telltale signs of deterioration can help build your program to eliminate preventable failures.

Predictable Failure Probability

Following the previous point, some types of components have massive historical data that can quantify the likelihood of failure. A common predictor of failure is the amount of usage. You can see how a preventive maintenance strategy can add value to such assets by scheduling servicing tasks at calculated milestones.

Low Risk of Random Failure

While some failures are predictable, other types of materials are more random in terms of their failure patterns. These might not be suitable for a preventive maintenance strategy. Instead, you want a set of equipment with a relatively low risk of random failure.

Hazardous Applications

Going back to one of the benefits of preventive maintenance, processes with a perceived operational risk can benefit from a preventive maintenance strategy. Preventive maintenance includes routine checks and inspections that can provide valuable information about the safety state of a plant.

Preventive Maintenance Workflow

Regardless of how you choose to design your program, typical preventive maintenance workflows would still have distinctive similarities with each other. A basic preventive maintenance workflow will go through the following steps:

1. Select an Asset

Designing your approach starts with identifying an asset. You might, for example, choose to use a similar program for similar types of equipment

2. Define a Preventive Maintenance Interval

One of the key elements of a PM process is identifying how PM tasks are triggered. A calendar- or usage-based interval might be measured by a certain number of operating hours.

3. The Time Interval Is Reached

After defining what to look out for, you then identify ways to be notified when such criteria are met. For the case of time-based schedules, this might be in terms of months, years, or hours of usage. More predictive approaches might require more specific criteria. 

4. Preventive Maintenance Task Is Assigned

After identifying the requirement for maintenance, the task is then assigned to the accountable groups. A PM task can be in the form of steps or procedures for an inspection or repair job. 

5. Maintenance Is Performed 

Maintenance is then executed, ideally with a standard procedure and checklist. Using CMMS software is particularly useful for this part. The status of maintenance work can be made available to other relevant groups of the company.

6. Repeat Preventive Maintenance Flow

Once an asset is back live, it can then operate as usual until the whole cycle repeats. 

preventive maintenance workflow graphic

Example of a preventive maintenance workflow

Preventive Maintenance Examples

Some aspects of a comprehensive preventive maintenance program are evidently applicable to particular equipment. Production line equipment should be properly maintained to prevent breakdown, and infrastructure elements such as heating, ventilation, and air conditioning (HVAC) should be routinely inspected, cleaned, and updated as required. However, there may be other systems that also need routine maintenance to prevent failure.

How about your water systems? Do you have appropriate filtration? Are you running warm water systems that may be a breeding area for serious bacterial infections such as Legionnaires Disease? How about your electrical systems and the need to ensure that they not only comply with legislation but do not degrade over time? Doors, stairways, lighting, and flooring all need periodic inspection and maintenance, too.

The list of what needs to be included in your preventive maintenance plan can be bewildering, but certain guidelines give you at least a basis to conform to. The American National Standards Institute (ANSI) carries a lot of information on preventive maintenance. It's a good place to start if you are unsure about the extent of the program that you need.

Preventive Maintenance vs. Reactive Maintenance

By now, you might have seen how preventive maintenance can increase reliability and be a practical choice for your facility. But how does it compare to the alternative―reactive maintenance?

First, let us define reactive maintenance. Reactive maintenance is a broad term referring to a maintenance approach where the need for repair comes after poor performance or failure is observed. Fixing something that's broken is arguably the oldest form of maintenance. Reactive maintenance makes sense for components that are relatively low-value and easy to replace. It's absurd to meticulously track how long a light bulb has been operating, when the alternative is easily replacing it at the earliest sign of a flicker. But as the stakes increase, you want to move away from surprises of failure and lean towards a more reliable approach.

To illustrate the difference between reactive and preventive maintenance, imagine a piece of equipment with a considerable impact on your business. In an unexpected failure scenario, you are most likely looking at a case of breakdown maintenance. These types of failures are what preventive maintenance tries to prevent from occurring in the first place. With unplanned downtime during breakdowns, you incur production losses for every minute spent on repairs. You would also typically have to shell out more dollars to expedite any required parts or services. In such scenarios, a proactive approach becomes more practical by getting ahead of a potentially disastrous event.

Both preventive and reactive maintenance have their advantages and disadvantages. Reactive maintenance would have significantly lower upfront costs. There are also possibly fewer redundancies as you would only perform repairs when absolutely necessary. On the other hand, you can think of a preventive strategy as more of an investment. There will be costs to set up measuring devices, perform inspections, and execute service tasks. The payoff is that you won't need to deal with big-time failures. In a preventive maintenance approach, you are trying to optimize tasks spread throughout time to eliminate future failures.

How Preventive Maintenance Decreases Downtime

Think about preventive maintenance in simple terms, such as with your car. Oil changes and regular servicing are part of a preventive maintenance schedule that ensures your car runs properly and without unexpected failure. If you ignore that maintenance schedule and miss service intervals, your car will depreciate in both value and utility. The same goes for machinery in manufacturing plants and equipment in facilities.

With a preventive maintenance schedule in place, maintenance managers can decrease downtime. This schedule is usually automated with a CMMS that comes with PM scheduling software. However, managers are always cautious of over-maintaining assets. There's a point where preventive maintenance starts costing too much in relation to the amount of downtime it prevents. 

Additional Resources

Preventive maintenance is a broad topic in itself. New developments and best practices about PM keep coming on top of the already existing foundations and frameworks formed over time. The good news is that there is an almost never-ending abundance of resources to explore. Whether you're just learning about preventive maintenance or you've had some previous experience, there are references out there to help expand awareness about it. To get you started on more specific topics, here are some resources related to preventive maintenance and maintenance in general.

1. Making a PM Checklist

A preventive maintenance checklist outlines the steps that workers need to do to complete a task. Making a proper checklist helps improve the quality and consistency of repair work.

2. Maintenance Statistics

A lot of fascinating data accumulates from various studies and surveys relating to maintenance. Here is a rundown of some quick facts and figures about the different types of maintenance.

3. Maintenance Applications

While there are several types of proactive maintenance, their definitions are still pretty broad. Different industries might have specific ways of applying the many various strategies.

4. Failure Mode and Effects Analysis

In earlier sections, we briefly mentioned how failure modes provide insights into whether or not preventive maintenance is applicable. This article takes a closer look into the process of failure mode and effects analysis (FMEA).

5. Moving From Reactive to Preventive Maintenance

Leaping from reactive to preventive maintenance can seem like a daunting task. This link provides useful tips to increase your confidence in taking on the challenge.

Conclusion

Preventive maintenance has a reputation for being costly and difficult to implement. But it should not take an episode of downtime or some catastrophic event to demonstrate how important it is to undertake a program of forward-looking maintenance. A preventive maintenance strategy is an investment that pays back not only in savings but also through an increased focus on safety. Implementing a preventive maintenance program does not need to be complicated, but it does require planning. Start by choosing a few critical assets, make a preventive maintenance checklist, then schedule the PMs in a CMMS.

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