Last Updated: January 5, 2022
What Is Preventive Maintenance?
Preventive maintenance (PM) is proactive monitoring and maintenance of assets that includes adjustments, cleaning, lubrication, repairs, and parts replacements. PM can reduce downtime and keep surprise repairs at bay. Preventive maintenance must be performed in a timely manner and be well-documented in order to be successful.
There are two main types of preventive maintenance: calendar-based maintenance, and usage-based maintenance.
Calendar-based maintenance is the most common type of preventive maintenance. It uses software to set up a recurring, time-based maintenance schedule. Depending on the type of asset, intervals may be weekly, monthly, quarterly, or annually.
Usage-based maintenance relies on how much an asset has been used, rather than the amount of time that has passed, to determine PM checks. Meter readings are logged in a company’s preventive maintenance software, and when specified measurements are reached, a task will automatically be created for a routine check.
Ultimately, the primary benefits of preventive maintenance come down to reliability. As you keep each asset in good repair, it’s less likely to break down and cause downtime.
Equipment and machinery do not live forever. A planned maintenance approach maximizes the value of an asset by making sure it gets the proper care to meet (and possibly exceed) its projected life expectancy.
The price of employee safety is never too high. Preventive maintenance keeps equipment in good order and running as expected, reducing accidents and malfunctions that could result in injury to employees.
Preventive maintenance increases savings by allowing companies to anticipate repairs needed in the near future. This reduces unplanned downtime and corrective repairs, which can be more costly than planned maintenance.
With planned maintenance comes better control of your employees’ schedules. You can arrange for more efficient and effective procedures, honor scheduling expectations, and avoid paying overtime.
There are a few reasons why preventive maintenance may not be the right route for every company, in every situation. Here are a few challenges to be aware of:
PM requires an up-front and ongoing investment. It may seem unnecessary, as long as there are no issues. Those costs, however, almost always prevent larger, unexpected costs later on. While the cost of preventive maintenance may seem high at first, it could end up helping a company save in the long run.
The ongoing costs discussed above include the hiring of staff members who are skilled in asset maintenance. PM is constantly being performed and is a labor-intensive task, requiring full-time experts.
The costs of a PM program can sometimes outweigh the costs of reactive maintenance if you’re doing too much preventive work. Some types of failures aren’t as threatening to your operations as others, and if you’re putting resources into preventing every conceivable type of problem, you may actually be wasting resources on PM. It’s important to strike a balance between failure prevention and reactive repair work.
Preventive maintenance software helps track, organize, and document the preventive maintenance process. It simplifies PM and ensures that all details are accessible to relevant team members.
Though preventive maintenance does require added labor hours, PM software streamlines the process to keep extra labor to a minimum. It can also help companies avoid the risk of over-maintenance by clearly documenting all screenings and creating unique, PM schedules for each individual asset.
There are three main styles of preventive maintenance software: EAM (Enterprise Asset Management), CMMS (Computerized Maintenance Management System), and AOM (Asset Operations Management).
Enterprise asset management (EAM) provides a comprehensive inventory and purchasing management functionality. It offers a wider range of functionality than a CMMS, and is a good option for large organizations with complex systems.
Computerized maintenance management system (CMMS) specifically tracks maintenance operations. It doesn’t offer as much flexibility as EAM, but works well for smaller businesses. It uses completed work orders to process and update asset records.
Asset operations management (AOM) is the latest, most robust type of preventive maintenance solution. AOM brings together maintenance, operations, and reliability teams for company-wide intelligence so each team can optimize their own resources. All of those resources, data points, and insights make PM as efficient and simple as possible.
First, you need to choose the best PM program for your business. For this step, it's important to keep five things in mind:
The cost of equipment failure and ease of monitoring should be considered when choosing the right maintenance strategy.
Make sure all stakeholders are represented and teams are multi-departmental.
Start with a critical analysis on the asset to evaluate the potential costs of failure.
Calculate the cost of monitoring the equipment relative to its overall cost.
Choose and implement a strategy, then monitor your progress and adjust as needed.
All PM workflows will have many distinctive similarities. A basic workflow will go through the following steps:
Designing your approach starts with identifying an asset. You might even choose to use a similar program for similar types of equipment
One of the key elements of a PM process is identifying how PM tasks are triggered. Equipment that is run consistently may benefit from a calendar-based approach, whereas equipment that is run intermittently might be better served by a usage-based strategy. You may also want to check with the manufacturer as well, to see if they have recommendations.
After defining what to look out for, you then identify ways to be notified when such criteria are met. In the case of calendar-based preventive maintenance schedules, this might be in terms of months, years, or hours of usage. For usage-based schedules, determine how much work the equipment can handle before it needs to be checked on.
After identifying the requirement for maintenance, the task is then assigned to the accountable groups. Decide how that task will be created and delivered, and what the procedure is once an employee has received it.
Maintenance is then executed, ideally with a standard procedure and checklist. Create a PM checklist for every piece of equipment in the system. Make sure there is also a standard procedure for the employee to indicate that PM has been completed.
Once an asset is back live, it can then operate as usual until the whole cycle repeats.
Regardless of your chosen PM program, the following steps will guide you through the implementation process:
Start by identifying which assets and processes have the most to gain from preventive maintenance (or the most to lose from a failure). According to IBM, as much as 50 percent of the money you spend creating a preventive maintenance plan can be wasted.
Once you identify and prioritize your equipment, move on to the skill set that's required for each maintenance task. By properly assigning tasks to the right level of trained employee or outside consultant, you'll maximize your labor investment.
The next step in implementing a program is to set up efficient work orders for your maintenance technicians. If you can minimize the time technicians spend traveling from one service project to the next, you'll find that your entire maintenance department will run more smoothly and efficiently.
Once you've established your maintenance schedule, be sure to incorporate it into your employees’ daily routine. Determine how much time PM orders will take, on which days, and make sure the hours are available.
In the real world, selecting the most suitable plan for an asset is not always straightforward. Here are a few factors that can help decide when to use preventive maintenance:
Part of this strategy is keeping a watchful eye on assets through inspection. Critical pieces of equipment benefit the most from the way this program manages your equipment.
What you know about your assets can mean the difference between successfully developing a plan or not. For example, equipment with predictable failure modes are good candidates for PM, because you can identify the paths a machine may take towards failure and build your program to minimize this risk.
Additionally, some components have massive historical data that can quantify the likelihood of failure—such as the amount of usage. Scheduling servicing tasks at calculated milestones for these assets is a good use of PM resources.
While some failures are predictable, other types of materials are more random in terms of their failure patterns. These might not be suitable for PM—especially if corrective maintenance is not particularly difficult or expensive. Focus PM efforts where you can reasonably expect to prevent an issue.
FInally, processes with a perceived operational risk can benefit from preventive maintenance. This strategy includes routine checks and inspections that can provide valuable information about the safety state of a plant.
There are three critical factors in a preventive maintenance program that you have to consider. Your answers to these questions will help you understand whether you need a PM program in place.
How bad is the worst-case scenario?
What is the likelihood of a breakdown?
How much will it cost?
Going from a reactive to a preventive maintenance culture can be overwhelming at first for many organizations. To help you answer the questions above, let’s look at four examples:
Case: Lube chains for critical equipment every seven days.
A breakdown on a critical piece of equipment could stop production. This could mean a loss of thousands, maybe millions, of dollars. Also, the likelihood of a breakdown is probably very high, because the equipment is constantly running. It’s a good idea to do a PM in this case.
Case: Replace light bulbs in the women’s bathroom every year.
The worst-case scenario is that a bulb burns out. The bathroom has multiple lights, so worst case: not so bad. The likelihood of a bulb going out at some point is pretty high, and the cost to do a PM on these lights every year is quite high given the relative impact it has. It doesn’t make sense to spend preventive maintenance resources here. Let’s just wait until a bulb burns out and get a work request to replace it.
Case: Change HVAC filter every six months.
The worst case is that the HVAC machine goes down. The likelihood of this is questionable. HVAC machines will still run with a clogged filter, but efficiency is reduced, causing increased costs. Do we PM this HVAC machine? Probably.
Let's look at an example of heavy machinery. Such an asset may be one of the most expensive pieces of equipment your business owns, and it can also be expensive to fix. In our example, this asset plays a critical role in the operation of your company on a daily basis.
If this machine costs $100,000 new and requires $30,000 in maintenance and repair over 7,000 hours of operation, we can effectively reduce those costs. In some cases, preventive maintenance may reduce overall maintenance costs by one quarter.
Rather than using time passed or usage to trigger work orders, predictive maintenance is only scheduled when specific conditions are met. Predictive maintenance establishes baselines, then uses IIoT devices to sync with software and trigger work orders. Vibrational analysis, acoustical analysis, and infrared analysis are the most common methods of measurement.
Like predictive maintenance, prescriptive maintenance uses IIoT and sensors to make predictions. However, this method takes the analysis of predictive maintenance a notch higher by not only predicting failure events, but also recommending actions to take. Potential outcomes when such recommended actions are performed are then calculated and anticipated.
Corrective maintenance, also known as reactive maintenance, is the process of making repairs once issues occur. When an asset breaks down, corrective maintenance is performed. Downtime always occurs with this method, though it does not require the upfront investment of PM.
Preventive maintenance is synonymous with preventative maintenance.
Preventive maintenance is a broad topic. Whether you're just learning about PM or you've had some previous experience, there are references out there to help expand awareness about it:
A checklist outlines the steps that workers need to fulfill to complete a preventive maintenance work order. Making a proper checklist helps improve the quality, productivity, and consistency of repair work and inspection.
A lot of fascinating industry data accumulates from various studies and surveys relating to maintenance. Here's a rundown of some quick facts and figures about the different types of maintenance.
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. Click here to learn more.
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).
Leaping from reactive to PM can seem like a daunting task. This article provides useful tips to increase your confidence in taking on the challenge.