Preventive vs Predictive Maintenance: Which Strategy Fits Your Plant?

What preventive maintenance means

Preventive maintenance is done on a schedule, based on time or running hours, whether or not the equipment shows a problem. Examples are greasing a bearing every month or replacing a belt every year.

It is simple to plan and needs no special instruments. The drawback is that parts can be replaced while still in good condition, and a failure that occurs between visits is still missed.

What predictive maintenance means

Predictive maintenance uses measurements of the machine's actual condition, such as vibration, temperature, oil analysis or motor current, to decide when work is needed. You act when the readings show a developing fault.

It cuts unnecessary replacement and can catch faults early, but it needs instruments, trained people and a baseline for each machine.

Where each approach fits

• Use preventive maintenance for low-cost, low-risk items and where failure is easy to fix: filters, belts, grease points on non-critical machines.
• Use predictive maintenance for critical rotating equipment where a failure stops production or is costly: main fans, large motors, pumps, gearboxes.
• Run-to-failure is acceptable only for cheap, non-critical items with spares on the shelf.

How to start

List your machines and rank them by the cost of an unplanned stop. Put the top few under condition monitoring, keep the rest on a schedule, and review the results every few months. Use the failure records to adjust both the schedules and the monitoring points.