Definition
Planned maintenance performed at fixed time or usage intervals, replacing parts, lubricating, and inspecting before equipment fails; on the maintenance maturity ladder given in teaching material 16 (third-party reordered document), it ranks after autonomous maintenance and before Predictive Maintenance; official places preventive and predictive maintenance on the same continuous spectrum, selected according to equipment conditions, without mandating an order. The English abbreviation PM is identical in form to the PM of Project Management; this table does not assign it an abbreviation, and the full name should be written when citing it.
In detail
Preventive Maintenance acts on a cycle without asking about the equipment's current condition, so some parts will inevitably be replaced too early; the cost of that portion buys a reduction in the number of failures, and judging whether it is worthwhile depends on the reduction in failure downtime. Third-party reordered materials (textbook 16) place it in the middle of the ladder; official REV5 places Preventive and Predictive Maintenance side by side on the same continuum, choosing one or using both according to equipment conditions, not as a before-and-after relationship. The practical levers are the TPM manual and checklists: cleaning, inspection, and lubrication requirements and owners are fixed in writing, and operators take on the autonomous maintenance portion. Before each activity ends, you must answer whether the maintenance plan has been formally revised; without revision, the same mistakes will recur.
Example in practice
A machine's bearings used to be replaced only after failure, with six stoppages a year. Switching to replacement by running hours and putting the check into the shift-start standard work cuts unplanned downtime to one event a year; part cost rises but the downtime loss is far larger.