Condition-Based vs Time-Based Maintenance
Time-based maintenance services equipment on a fixed schedule whether it needs it or not; condition-based maintenance monitors actual equipment condition and intervenes only when the data shows a developing fault. Condition-based avoids both over-servicing and surprise failures, but needs monitoring and analysis. Time-based is simpler and fine for low-criticality or wear-predictable assets.
These are the two dominant preventive strategies, and the difference is what triggers the work: the calendar, or the evidence. The right choice depends on asset criticality, failure patterns and the cost of monitoring.
Condition-based maintenance vs Time-based maintenance — at a glance
| Dimension | Condition-based maintenance | Time-based maintenance |
|---|---|---|
| Trigger | Measured condition (vibration, temp, oil…) | Fixed time or usage interval |
| Over-servicing risk | Low — act only when needed | High — services healthy machines |
| Surprise-failure risk | Low — catches developing faults | Higher — misses faults between intervals |
| Setup effort | Higher — sensors, baselines, analysis | Low — schedule and execute |
| Best for | Critical assets; costly downtime | Low-criticality or wear-predictable items |
| Data needed | Condition-monitoring data | Minimal |
When to choose Condition-based maintenance
Choose condition-based maintenance for critical, continuously-running assets where unplanned failure is costly and faults develop detectably — the monitoring investment pays back through avoided downtime and extended intervals on healthy machines.
When to choose Time-based maintenance
Time-based maintenance remains sensible for low-criticality assets, items with predictable wear, or where condition monitoring is impractical or uneconomic — its simplicity is a genuine advantage there.
Verdict
Condition-based maintenance is superior for critical assets where downtime is expensive; time-based is the pragmatic default for everything else. Most plants run a mix, set by an asset-criticality ranking rather than a blanket policy.
FAQ
Is condition-based maintenance always better?
Not always. For low-criticality assets or predictable wear items, the cost of monitoring may exceed the benefit, and time-based maintenance is more economical. Criticality ranking decides which assets justify condition monitoring.
How do I choose per asset?
Run an asset-criticality ranking: high-consequence, continuously-running assets justify condition-based monitoring; low-consequence ones default to time-based or run-to-failure.
Related
Condition-Based Maintenance (CBM) · Asset Criticality · P-F Curve
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