What is the difference between preventive maintenance and predictive maintenance?

• A. Preventive maintenance uses condition monitoring data only.
• B. Preventive maintenance is based on condition monitoring; predictive uses time.
• C. Predictive maintenance is scheduled based on time or usage.
• D. Preventive maintenance is scheduled based on time or usage; predictive uses condition monitoring data to perform maintenance just before failure.

Answer: (D)

The main idea is how maintenance decisions are triggered: by a fixed schedule or by actual equipment health. Preventive maintenance is planned at regular intervals based on time or usage, such as every 6 months or every 1,000 operating hours, regardless of how the component is performing at the moment. This makes planning straightforward and consistent, but it can lead to replacing parts that are still fine or missing faults that develop sooner or later than the schedule.

Predictive maintenance, on the other hand, relies on data about the equipment’s condition. By monitoring indicators like vibration, temperature, oil quality, wear debris, or electrical signals, technicians estimate how close a part is to failing and perform maintenance just before that failure would occur. This approach aims to minimize downtime and unnecessary maintenance by targeting interventions only when the health data say they’re needed.

So, the correct statement distinguishes between time/usage-based scheduling for preventive maintenance and condition-monitoring-based decision-making for predictive maintenance.