Preventive maintenance (PM) isn’t about changing filters on a calendar—it’s about predicting wear and acting before failure hits. In high-use process plants, the most accurate way to schedule PM is by tracking actual runtime hours instead of fixed intervals. When done right, this method reduces unexpected breakdowns, eliminates unnecessary service, and optimizes technician bandwidth.
Why Calendar-Based PM Doesn’t Cut It
Calendar-based maintenance works in low-variation environments. But in most plants, usage is uneven. One forming line might run 24/7, while another sits idle half the week. Servicing both machines every 30 days makes no operational sense.
Runtime-based maintenance aligns service intervals with actual equipment workload. You’re no longer guessing — you’re responding to real usage.
Start With Equipment That Has the Most Impact
Don’t try to convert everything at once. Begin with high-capital, high-criticality assets:
Glass tempering furnaces
Annealing lehrs
Rotary kilns
Conveyors and motors with continuous load
These machines often include hour meters or PLC-based runtime trackers, making data capture straightforward.
Use the Right Triggers
Runtime-based PM depends on accurate tracking. Options include:
Built-in digital hour meters on motors, pumps, and fans
PLC timers integrated with MES or SCADA systems
Smart sensors that measure actual cycles or workload
Set PM thresholds based on OEM recommendations or internal failure history. For example: “Lubricate conveyor bearings every 300 runtime hours” instead of “every 3 weeks.”
Automate Your Scheduling
Modern CMMS platforms allow for dynamic PM scheduling. Once a threshold is hit—say 500 hours of use—a work order is generated automatically. This removes guesswork and ensures that service isn’t delayed or forgotten during busy shifts.
For example, when a kiln’s burner assembly crosses 1,000 hours, an inspection ticket auto-triggers with assigned technicians and parts list.
Adjust Based on Performance History
Your runtime thresholds shouldn’t be static. As you gather data, adjust PM frequency based on actual wear rates. If a blower fan consistently lasts 900 hours before vibration increases, you might shift service from 1,000 to 850 hours.
This fine-tuning improves uptime and reduces the “PM-induced failure” syndrome where over-servicing introduces new problems.
Don’t Forget Supporting Systems
Runtime hours shouldn’t apply only to mechanical components. Auxiliary systems like chillers, compressed air lines, and even dust collection filters benefit from usage-based triggers. You’ll avoid premature replacement and cut consumable costs.
Final Word
Runtime-based PM is more precise, more efficient, and ultimately more reliable. It lets your maintenance team act with confidence—based on data, not deadlines. If your PM program still runs on a calendar, it’s time to put runtime at the center of your strategy.
