What Is Preventive Maintenance? - TWI Global

Preventive maintenance (PM) is the regular and routine maintenance of equipment and assets in order to keep them running and prevent any costly unplanned downtime from unexpected equipment failure.

A successful maintenance strategy requires planning and scheduling maintenance of equipment before a problem occurs. A good preventive maintenance plan also involves keeping records of past inspections and the servicing of equipment.

Because of the complexity of maintaining a preventive maintenance schedule for a large amount of equipment, many companies use preventive maintenance software to organise their required preventive maintenance tasks.

What are the Types of Preventive Maintenance?

PM is used to anticipate and prevent the breakdown of equipment and should ideally be performed on all items of equipment to prevent age-related failure. Manufacturers often provide recommendations to maintain a piece of equipment but, generally speaking, there are three main types of preventive maintenance task:

Mandatory / Non-Mandatory Tasks

Mandatory tasks are those that must be performed as soon as they are due and will often include safety-critical checks. Non-mandatory tasks are still important, but can be delayed without resulting in a critical failure or performance reduction. A preventive maintenance checklist should split tasks into mandatory or non-mandatory.

Pyramiding / Non-Pyramiding Tasks

Pyramiding tasks occur when maintenance is set for a due date but is not completed and overlaps with a later scheduled maintenance. In this instance, should a new PM task become due, the previous one is cancelled. A cancellation should include a note to explain this and the new task should include the original due date to monitor how overdue the task is. Some companies prefer a non-pyramiding structure, which removes the need to note the original missed task and just takes the new date as the baseline.

Inspection and Task Oriented Tasks

Inspection tasks require checks to be made before the results are turned into work orders for planned maintenance to fix any problems that have been discovered. Task oriented PMs allow for minor repairs and adjustments to be made at the time of inspection, reducing the amount of work that needs to be written up as work orders on the inspection sheet.

When is Preventive Maintenance Required?

The exact requirement for preventive maintenance will vary depending on the equipment and the operation it is performing. Industry uses standards to help determine schedules for maintenance so that assets do not run to failure. These guidelines will also cover the type of inspection or maintenance that is needed.

Ideally, by following guidelines set down by manufacturers or standards, a PM schedule should ensure proactive maintenance rather than having to resort to reactive maintenance when something has already begun to fail.

Following this type of predictive maintenance schedule, through tasks such as condition monitoring, requires accurate recording of inspections and servicing against an understanding of the lifespan of a particular piece of equipment. These records will help determine when preventive maintenance is required.