What Is Preventive Maintenance (PM)?

Preventive Maintenance (PM) Explained

A PM program defines for each asset a set of tasks and a trigger. Triggers are either time-based (every 30 days) or usage-based (every 500 run hours, every 100,000 cycles) using meter readings. When the trigger is reached, the system generates a work order from a job plan that lists tasks, estimated labor, required parts and safety steps.

In SAP the schedule lives in a maintenance plan (transaction IP10 schedules it) that generates orders from task lists. In IBM Maximo the Preventive Maintenance application generates work orders from a PM record, job plan and optional meters. Oracle EAM, Infor EAM, IFS and Dynamics 365 have equivalents. In a CMMS the same logic exists under names such as PM schedule or recurring work.

Good PM is selective. Time-based tasks suit parts with age-related wear, such as lubrication and filters. Many failures are random and not prevented by fixed-interval work, and each intrusive PM can itself introduce errors. That is why reliability-centered maintenance and condition-based maintenance exist: to decide which tasks truly reduce risk and to replace some fixed intervals with measured condition.

PM compliance, the share of scheduled PMs completed on time, is the standard health metric. A related caution: high compliance with poor task content produces a busy but ineffective program. Review tasks against failure history, not just completion rates.