Preventive Maintenance (PM) 101

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Understanding Preventive Maintenance (PM)


One of the everyday challenges many businesses face is equipment and plant failures. It doesn’t matter if you have a fleet of machines, manage an office, warehouse, restaurant or retail establishment.

For companies that depend on only a few machines to operate, the challenges posed by equipment breakdowns are significantly less. However, for establishments like construction firms, mining operations and manufacturing facilities that depend on hundreds of plant and equipment, machine breakdowns can mean major losses in terms of productivity, revenue and reputation.

This is where preventive maintenance comes in.

Big issues usually start as small, preventable problems. The most devastating workplace accidents, operational losses, and interruptions in production arise from failures in maintenance systems as well as in internal communication.

With a smart preventive maintenance system in place, you not only reduce premature asset failure or breakdowns but also ensure workplace safety and save hundreds of thousands or even millions of dollars in the process.

What Is Preventive Maintenance, or PM?

Preventive Maintenance (PM) refers to routine maintenance designed to ensure equipment is in tip-top condition and running efficiently. Its primary objective is to prevent unplanned downtime as well as the significant expenses arising from unexpected equipment failure.

Other objectives of preventive maintenance include:

  • Ensuring the plant, equipment and machinery are in optimal condition and ready for use
  • Increasing the lifespan of equipment and machines
  • Reduction of maintenance, repair costs and the need for spare parts
  • Maintaining the optimum productive efficiency, operational accuracy and capacity, and value of assets through periodic inspection, repair, etc.
  • Improvement and maintenance of product quality, consistency and output
  • Reducing the workload and odd-time work of maintenance personnel, therefore,
  • Reducing the maintenance workforce size
  • Achieving maximum production capacity
  • Ensuring the safety of workers and minimising risks in the workplace, therefore,
  • Maintaining compliance with the Mines Safety and Inspection Act and Regulations
  • Acting in accordance with the Occupational Safety and Health Act and Regulations

Basic preventive maintenance requires the careful planning and scheduling of equipment maintenance activities before an actual problem presents itself. It also entails keeping up-to-date records of previous inspections and servicing reports.

Inspection testing, such as non-destructive testing and preventive management can be a very complex process, particularly in companies that use and maintain a lot of equipment. In these instances, companies rely on preventive maintenance software and asset management services to organise, schedule and implement all preventive maintenance tasks.

Meaning and Definition of Preventive Maintenance

Although knowing the meaning of preventive maintenance is important, your attention should be on what it actually entails. And, since we have already defined preventive maintenance in the previous section, we’ll discuss the specifics here.

On a basic level, a preventive maintenance checklist usually includes the following activities:

  • Creating a centralised checklist of all equipment or mechanical assets based on age, function, cost, workload importance, history of failures, etc.
  • Using the above checklist during inspections
  • Visual inspection of all units and components to ensure their cleanliness and functionality and, more importantly, to uncover conditions that can lead to equipment failure and production breakdown, this may also include various types of condition monitoring
  • Addressing such conditions while they are still minor, through the repair or replacement of worn-out parts; cleaning, greasing and oiling of all moving parts; conducting periodic machine overhauling
  • An environmental sweep to ensure the site where assets are kept is in optimum condition
  • Event log inspection to check for patterns or trends and any unusual activity
  • Installing equipment or machinery prone to sudden failures in duplicate form. These include pumps, motors, compressors, transformers, etc.
  • Scheduling future inspection and maintenance dates with specific assignments to responsible inspectors who are equipped to handle simple repairs or minor issues

Preventive maintenance falls under two broad categories:

  • Running maintenance: Maintenance work carried out while the machine or equipment is in service.
  • Shutdown maintenance: Maintenance work when the machine or equipment is not running or being operated.

However, there are very specific types of preventive maintenance, which we will introduce later in this article.

Preventive Maintenance Applications

Preventive maintenance is usually applied to automated or continuous production processes, as in the case of mining, chemical plants, factory assembly lines, automobile manufacturing and data centres.

In most of these situations, the cost of lost production due to equipment failure or breakdowns can be considerably high. Aside from production losses and the cost of equipment repair or replacement, certain mechanical breakdowns can be very destructive, such as a small equipment failure leading to a total system breakdown. This means that preventive maintenance systems are crucial in cases where there is a need to ensure continuous and breakdown-free plant operations.

Preventive maintenance is usually crucial in the following industries:

  • Mining
  • Construction
  • Facility management
  • Fleet management
  • Government buildings and infrastructure
  • Hospitals
  • Manufacturing
  • Oil and gas
  • Transport
  • Rail
  • Schools
  • Utility services

Preventive maintenance is also an important system in data centres that depend on the continuous running of computers and IT equipment for their operation.

Advantages and Disadvantages of Preventive Maintenance

Based on the objectives of preventive maintenance, it is obvious that this process offers several benefits.  However, you might be surprised to know that preventive maintenance has both advantages and disadvantages.

The decision to adopt a preventive maintenance system or not will largely fall back to the overall company strategy of whether to enhance and prolong the equipment or run to failure. A preventive maintenance strategy is often implemented along with a reliability centred maintenance program.

Below are the benefits of preventive maintenance, as well as the disadvantages:

Benefits of Preventive Maintenance

Benefits of preventive maintenance

The importance of preventive maintenance to businesses lies in the following benefits it offers:

  • Reduction of workplace risks: When business assets (i.e., tools and equipment) are inspected and maintained periodically, a company can reduce the risks of unplanned downtime or unexpected mechanical breakdowns. This way, they can provide their people a safer work environment.
  • Longevity of equipment lifespan: When machines, plant or equipment are checked according to a maintenance schedule, it becomes easier to ensure business assets are in good working condition. This, in turn, can improve the performance and extend the functional lifetime of business assets.
  • Optimised operation and productivity: Since there are fewer disruptions to operations, businesses can meet or exceed productivity goals. And since maintenance schedules are pre-planned and communicated accordingly, maintenance activities will have little to no impact on business productivity and efficiency.
  • Reduction of costs: Preventive maintenance helps keep costs down by preventing equipment failure and unplanned downtime. Since minor problems are addressed right away, they do not entail expensive repair, downtime, or replacement costs.
  • Energy and resource usage efficiency: Mechanical assets or equipment that are malfunctioning or poorly maintained tend to consume more (waste) energy and other resources (e.g., water). But with preventive maintenance, such situations can be avoided.

Disadvantages of preventive maintenance

Preventive maintenance is a highly beneficial business process.  However, preventive maintenance also comes with a couple of disadvantages:

  • Significant investment: You need to have a separate budget for the successful adoption of preventive maintenance. You might also need to invest in training, tools and equipment that will allow you to perform maintenance tasks efficiently. The cost of acquiring and implementing a computerised maintenance management system (CMMS) can be especially unbearable for small-scale operations or businesses that do not have a budget allocated for asset management and maintenance.
  • Requirement for onsite inspectors and maintenance personnel: Unlike in reactive maintenance where you call in a technician or mechanic to fix a machine as needed, you need people onsite to conduct preventive maintenance activities regularly.
  • Over-maintenance: A regular maintenance plan requires inspectors to check and inspect all business assets, including those that may not need to be checked as often. This can equate to a significant amount of wasted work hours and labour costs if left unchecked. To prevent this, you need to continuously review and change your maintenance plan for such items or equipment.

Different Types of Preventive Maintenance

Types of Preventive Maintenance

There are different types of preventive maintenance used for various reasons and suitability. The following are some examples of preventive maintenance methods:

Time-Based Maintenance (TBM)

Also referred to as ‘calendar-based maintenance’, time-based maintenance entails the creation of a maintenance schedule based on specific dates (e.g., every 5th or 10th of every month) or a time interval such as a certain number of days (e.g., every 15 days)

This maintenance method is very helpful in complying with manufacturer recommendations for inspecting and cleaning equipment. It is also crucial for guaranteeing your most essential equipment is checked regularly to maintain optimum running efficiency.

Common examples of calendar-based maintenance include getting your air conditioning system serviced before summer, cleaning your ventilation system in compliance with health regulations and conducting exterior sealant inspections every three years.

Usage-Based Maintenance (UBM)

Businesses that depend on certain machinery or equipment for their daily operations need to track usage through equipment monitors or measuring operating hours or tracking production cycles. The usage-based maintenance method is especially useful if assets do not produce tickets or send notifications automatically, even after reaching a certain number of operating hours.

Examples of this include pump lubrication after every 6,000 run hours, vehicle oil change or testing an important piece of machinery after it has reached a certain number of running hours. By staying on top of the proper care and maintenance of equipment, you can ensure the longevity of the functional lifespan of important (and usually expensive) equipment.

Failure-Finding Maintenance (FFM)

Failure-finding maintenance focuses on checking or inspecting a piece of equipment for hidden failures or unknown defects. The goal here is not to maintain a certain asset but to test it for functionality — which is why this method is sometimes termed as a ‘functional check’. Condition monitoring falls into this category.

Failure-finding tasks are valuable in that they are necessary to ensure the maximum reliability of security and backup systems. This maintenance method is crucial for ball mills, girth gears, bearings, screening and testing alarm systems, backup systems, mitigation systems, etc.

This maintenance method is usually necessary for instances where equipment or device failure is usually not obvious or easily detectible.

Commonly in the mining industry, ball mills will be equipped with vibration devices to detect the start or change of vibration signals. The teeth on girth gears are examined via fluro-magnetic particle techniques.

Another example is, any defects in a fire alarm system can remain undetected under normal circumstances or during routine preventive maintenance. In such cases, testing the fire alarm system will ascertain whether it is working as it should.

Importance of a Preventive Maintenance Policy

A preventive maintenance policy is a company’s strategy, plan or blueprint in implementing preventive maintenance tasks. It is a comprehensive document that includes a company’s preventive maintenance policy and procedures.

With a preventive maintenance policy in place, everyone in the company knows what is expected of them in terms of checking, inspecting, and caring for assets. It also ensures the systematic implementation of preventive maintenance and its widespread application in a company.

If you are in the early phases of adopting preventive maintenance in your company, there are excellent preventive maintenance policy templates available, also through AME, that you can use as a basis for building your own.

What Does a Preventive Maintenance Strategy Look Like?

Preventive Maintenance Strategy

A preventive maintenance strategy includes the following critical details and information:

  • Definition of PM goals
  • The asset and maintenance tracking method to be implemented (Excel, CMMS, etc.)
  • A plant and equipment audit for gauging the site’s compliance with codes or regulations
  • Sourcing of missing documents, such as equipment manufacturer’s manuals, asset breakdown and failure history, repair or parts replacement records, etc.
  • Creation of a preventive maintenance plan or schedule which may include,
    • Control documents,
    • Detailed work instructions (PM1’s),
    • A listing of critical spares,
    • Examination of parts supply line, (especially through times of pandemics)
  • Preventive maintenance reports or records

Preventive Maintenance Schedule Explained

There are two distinct methods falling under preventive maintenance scheduling: fixed PMs and floating PMs. You can use either method to track assets and decide when they need to undergo inspection, repair, recalibration or replacement.

Both strategies enable maintenance facilities to track maintenance triggers and ensure assets are maintained efficiently.

Fixed PM Schedule

This involves scheduling maintenance at a certain time or usage interval. It doesn’t take into account when the last PM was done. For example, a PM is scheduled for a certain tower crane every Monday. Even if last Monday’s task was conducted and completed on Tuesday or was never finished, a new PM work order is triggered for the following Monday. A fixed PM schedule doesn’t consider what was done to that specific tower crane in the past; its only concern is the planned PM for the future.

Floating PM Schedule

Unlike fixed PM schedules, floating PMs are scheduled based on the timing of the previous PM, so they don’t have a specific date attached. This means the date of the PM work order varies as it is based on the maintenance history or previous usage of a piece of equipment.

For example, the preventive maintenance interval for another tower crane is 10 days. With a floating PM schedule, the work order is not made 10 days from when the last PM was supposed to happen. Instead, the work order basis would be 10 days from the time the PM for the tower crane was actually conducted and completed. If the work order for the tower crane is left open, the next PM will not be triggered.

Why Use Preventive Maintenance Software

With the complexity of today’s plant operations and the extensive adoption of digital technology, using pen and paper and even Excel is considered time-consuming and generally inefficient.

Instead, businesses can use preventive maintenance software that stores maintenance data on a computer or in the cloud. This centralised database makes it easy to keep track of all PM activities. Here, you can manage work orders, inventory, maintenance records, etc.  Classified plant management systems (CPMS) and computerised maintenance management systems (CMMS) are examples of PM software you can use.

Difference Between Preventive Maintenance and Other Types of Maintenance Strategies

There are certain types of maintenance strategies that are usually compared to preventive maintenance, including the following.

Predictive vs Preventive Maintenance

Predictive maintenance or PdM is scheduled as needed using the current or real-time condition of assets, thereby reducing labour and material costs. However, predictive maintenance program implementation requires more investment than a typical PM strategy.

Preventive vs Corrective (Reactive) Maintenance

Unlike PM whose goal is to prevent equipment failure, corrective maintenance is focused on identifying and correcting a fault after it has manifested itself in working equipment. Different companies might find either method more cost-effective than the other depending on their assets and industry.

Breakdown Maintenance vs Preventive Maintenance

While PM works to identify equipment issues to prevent failure, breakdown maintenance allows for the running of equipment until it breaks down or stops working before repair and maintenance are conducted.

Preventive Maintenance for Business Success

Preventive maintenance, when done right with the help of asset management experts, can help your business save on costs, extend the functional lifespan of assets and ensure you have a safe workplace for your employees.

If you’re intent on adopting PM for your business, please get in touch with us at AME.