Corrective Maintenance
Corrective maintenance (CM) is any maintenance action performed after a failure occurs to identify, isolate, and rectify the fault, restoring equipment to its operational state within established tolerances. It is quantified by Mean Time to Repair (MTTR) and is fundamentally reactive, contrasting with preventive or predictive strategies.
On the shop floor, corrective maintenance is triggered by fault detection such as machine stops, alarms, or visual leaks, followed by diagnosis, part replacement or repair, and functional testing before returning to production. In CMMS systems like ServiceGrid, CM is logged as an unplanned work order capturing failure mode, root cause, labor hours, and parts used to calculate MTTR and reliability metrics. CM is subdivided into Emergency Maintenance for immediate unplanned failures and Deferred Corrective Maintenance for planned, kitted, and staged non-urgent failures.
- Run-to-Failure Strategy: Waiting for non-critical assets to fail without monitoring leads to unexpected downtime and cascading damage on critical lines.
- Reactive Firefighting: Lack of spare parts inventory or skilled technicians for CM tasks causes extended MTTR and production delays.
- Deferred CM Mismanagement: Delaying non-urgent failures without proper planning, such as missing kitting or procedures, turns deferred maintenance into emergency breakdowns due to worsening failure modes.
How does CM differ from Run-to-Failure (RTF)?
CM is an action post-failure; RTF is a strategy of intentionally allowing failure. CM can be planned (deferred), whereas RTF is always unplanned.
What KPI best measures CM effectiveness?
MTTR (Mean Time to Repair), reflecting speed and efficiency of restoring assets.
When is CM appropriate in reliability engineering?
For low-cost, non-critical assets with low wear, where preventive costs exceed failure consequences.
Can CM reduce reliability?
Yes, if assets are neglected until failure; CM decreases long-term reliability by allowing wear to progress unchecked, increasing long-term costs via downtime and secondary damage.