What is Preventive maitenance and Predictive maintenance?

Preventive Maintenance

A maintenance activity based on elapsed time since the last activity, hours in use, or similar criteria with the objective of preventing failures. Examples include replacing lubricant, filters, or other wear components.

The term preventive maintenance also includes a wide range of planned maintenance activities that are part of the reliability program. Examples include calibration, predictive maintenance, and planned overhaul (e.g., for rotating equipment).

Calibration - Method of testing instruments or similar devices to determine accuracy and to adjust instruments if needed to achieve a target accuracy.

Predictive Maintenance

Equipment testing used to detect the onset of failure, evaluate the current condition, and determine if further maintenance activity is required for a piece of equipment. Examples include vibration analysis, oil analysis, and thermography.