Preventative and corrective maintenance

Preventative Maintenance

Preventative maintenance refers to regular, routine work completed to keep equipment running and to prevent any unplanned downtime or expensive repairs.
The objective of preventative maintenance is to maximise the availability and reliability of equipment and systems, extending their useful life.
Scheduled inspections and maintenance tasks at regular interval forms a crucial part of preventative maintenance. This involves activities such as cleaning, lubrication, minor adjustments, and component replacements.
Having a maintenance schedule based on equipment’s operational hours, wear and tear rate or recommendations from the manufacturer.
Documenting the history of preventative maintenance not only demonstrates compliance to safety regulators but also helps in predicting future equipment failure modes.

Corrective maintenance involves any tasks undertaken to correct a fault so that the failed equipment, machine, or system can be restored to an operational condition.
This maintenance type is often a reactive approach, as it’s performed after a fault has occurred, but it can be a part of a proactive strategy if it’s following the identification of potential issues during preventative maintenance.
Corrective maintenance tasks include the repair or replacement of parts, fault isolation, and often more extensive overhaul or a total replacement of the systems or equipment.
When doing corrective maintenance, the aim is to minimise the downtime, return the asset to its desired working state, and avoid interruption of production.
As with preventative maintenance, recording all actions taken during corrective maintenance helps to build a history of machine behaviour.

The main distinction between preventative and corrective maintenance lies in when they are executed. Preventative maintenance happens before a fault occurs to prevent it, while corrective maintenance occurs after a fault to correct it.
A balance between preventative and corrective maintenance is often established in an organisation to optimise both equipment reliability and cost-effectiveness. Too much preventative maintenance can lead to unnecessary labour and part replacement costs, while an over-reliance on corrective maintenance can lead to increased down-time and more extensive repair requirements.
A well-functioning maintenance system will be characterised by a carefully measured mix of both preventative and corrective maintenance, informed by an understanding of the operational context and backed up by accurate record-keeping.