Preventive Maintenance (PM)

Preventive Maintenance (PM) is a reliability-based Maintenance Strategy used to identify and monitor equipment or system condition and the failure modes of that equipment or systems prior to fault or failure. It can be divided into two subgroups:

• time based invasive maintenance
• time based inspections (often invasive).

PM schedules are typically based on OEM recommendations, requirements of codes of practice, legislation, expert opinion and recommendations.

While PM is generally considered to be worthwhile, there are risks such as equipment failure (following the bath tub curve 80% of failures are random) or human error involved when performing invasive maintenance. The ‘old’ adage is “Don’t touch it, unless it is broken”.

As with Run To Failure (RTF) the implementation of PM certainly has it’s place and a Maintenance Strategy Review will determine if that is the case.

Taking the RTF example to the next stage:

An individual bought an incandescent light bulb. The manufacturing company mentioned that the life span of the bulb is 3 years. Just before the 3 years, the individual decided to replace the bulb with a new one. This is PM.
The questions are:
“How often does the bulb fail before it is changed?”
“How much life is left in the bulb when it is changed?”
”How much life is being wasted by replacing it?”