By Yossi Tuchner, vibration specialist certified to
ISO 18436 CAT II
Why Maintenance Strategy Matters
Every plant, hospital or large commercial facility invests time and money maintaining its machinery, including
rotating equipment. Whether defined formally or not, there is always a maintenance approach that guides what the
technical team does before a failure and when a failure occurs.
Breakdown Maintenance (Run to Failure)
The simplest approach is to perform no diagnostic checks and fix machines only after they fail, assuming this
minimizes maintenance expense. In practice the drawbacks are significant:
- Secondary damage spreads beyond the original fault, increasing repair scope and cost.
- Higher safety and environmental risk because failures are unplanned and their extent is unknown.
- Longer downtime due to larger, unexpected repairs.
- Greater indirect costs: larger spares inventory for emergencies, overtime labor and urgent contractor work.
- Total uncertainty regarding when and how a failure will occur.
Preventive (Time-based or Planned) Maintenance
Preventive maintenance follows a calendar or runtime plan based on OEM recommendations, statistics or past
experience. The intent is to intervene before failure, regardless of actual condition. Key limitations include:
-
Intentional shortening of MTBR (Mean Time Between Repairs) because work is done earlier than
necessary, which leads to over-maintenance of healthy assets.
- Failures still occur between scheduled tasks, often earlier than expected.
- Large spares inventory is still required, both for planned work and for unplanned events.
- Little visibility into what will fail next and when.
-
Overall, a more expensive form of breakdown maintenance that does not address the root causes driving failure.
Predictive Maintenance (PdM)
Predictive maintenance monitors machine condition at defined intervals and performs maintenance only when indicators
show a developing fault. Compared with purely time-based work, PdM yields substantial savings because the right work
is done at the right time, before damage escalates.
Benefits include earlier fault detection and faster decision-making, which lead to smaller repair scope, lower
energy losses due to friction and heat, and lower total cost of failure. PdM also allows maintenance to schedule
interventions when operations can accommodate them, turning “unplanned stops” into short, well-planned tasks.
Typical PdM tools: vibration monitoring and analysis, thermography, ultrasound, motor current analysis and oil
condition assessment. Together they provide a clear forecast of deterioration and support accurate planning.
Proactive Maintenance (PrM)
Proactive maintenance goes a step further. While applying PdM, recurring failure modes may appear over time. PrM
addresses the causes of those patterns by recommending engineering changes to components, operating conditions or
other influencing factors to extend asset life even beyond its original baseline.
In effect, PrM “stretches” the bathtub curve by raising reliability for the long term through design and operating
improvements.
Summary
Implementing PdM and PrM delivers a step change in availability and cost: faster decisions from early detection,
targeted corrective actions, improved product quality, higher safety, reduced spares inventory and lower total
maintenance cost. The path forward is clear: measure condition, act on evidence, and remove the root causes that
drive failure.