Preventive Maintenance

What is preventive maintenance?

Preventive maintenance is a type of proactive maintenance that keeps assets in good order and reduces unscheduled downtime and major repairs.

Preventive maintenance workflow


Preventive maintenance, also spelled preventative maintenance, is carried out with the goal of increasing asset lifetime by preventing excess depreciation and impairment or untimely breakdown. This maintenance 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 preventive maintenance required varies. Because of this, it can be challenging to establish a successful preventive maintenance program. However, a good rule of thumb is to start with a time-based PM program.

Types of preventive maintenance

Any maintenance that is not reactive maintenance is preventive maintenance. And there are many different types of preventive maintenance that require different types of technology and expertise.

Four common types of preventive maintenance (PM) include:

  • Calendar-based maintenance — A recurring work order is scheduled for when a specified time interval is reached in the computerized maintenance management system (CMMS).
  • Usage-based maintenance — Meter readings are used and logged in the CMMS. When a specific unit is reached, a work order is created for routine maintenance.
  • Predictive maintenance — 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 PMs to prevent them from happening again.
  • Prescriptive maintenance — This is similar to predictive maintenance, but instead of only the maintenance manager prescribing PMs, machine learning software assists them.

How preventive maintenance decreases downtime

Think about it 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 value and utility. The same goes for machinery in manufacturing plants and equipment in facilities.

With a PM 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.

The optimal amount of preventive maintenance occurs when the cost of corrective and preventive maintenance meet. [Source]

Examples of preventive maintenance

Some aspects of a solid preventive maintenance program are obvious. Production line equipment should be suitably 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 there are certain guidelines that give you at least a basis to conform too. The American National Standards Institute (ANSI) carries a lot of information on preventive maintenance and is a good place to start if you are unsure as to the extent of the program that you need.

Benefits of preventive maintenance

There are more benefits of implementing a preventive maintenance program than merely reducing the amount of unplanned downtime. Other benefits include:

  • Extension of asset lifetime
  • Increased safety and reduced risk of injury
  • Optimized maintenance planning and resource allocation
  • Less expensive corrective repairs
  • Better margins and profits due to less downtime

Perhaps the greatest benefit is increased safety, especially for a company that owns heavy machinery. The price of employee safety is never too high and organizations such as the Occupational Health and Safety Administration (OHSA) rigorously enforce government policy.


Preventive maintenance is often seen as an overhead cost that is difficult to justify. But it takes just one period of downtime or a single notifiable accident to demonstrate how important it is to undertake a program of forward-looking maintenance. To start implementing a PM program, choose a few critical assets, make a preventive maintenance checklist, then schedule the PMs in a CMMS.