What determines the recommended preventive maintenance interval in an equipment?

This question has a broader perspective if it were to be answered exactly the way it comes because of the usage of  Equipment. However, i will limit my scenario on Computer as an equipment.

To determine a preventive maintenance interval of an equipment, the followings will be considered firstly;

1- Frequency of Usage

2- Condition of the atmosphere where the equipment is kept

3- Acceptable Usage Culture: this includes proper booting up and shutting down the system, having licensed sofwares like Antivirus and anti-ware etc

All these factors stated above will enable one to determine the FDP of an equipment. i.e Failure Developing Period which is the time period from when it is possible to detect a failure until we have a breakdown.  A failure is when a system or equipment is operating correctly within given parameters, but has signs of problems.

Example: if a server system is being put to max/min usage with all the parameters listed above in action, and a problem like dragging/ slowness or system is hanging for few seconds is detected. If the bugs or failures started at1st September,2014 and the system broke down at15th September,2014.

Therefore, maintenance Preventive interval = FDP/2

FDP =1-15 =14

=14/2

=7days interval.

If the inspection frequency is longer than7 days interval, we may miss both the failure and we will have a breakdown.  So, our rule of thumb is Inspection frequency = FDP/2.  

The real problem is that we don’t know what the FDP is most times.  There is no standard, no documentation and most equipments do not have any history on FDP.

It determines the recommended preventive maintenance interval in an equipment history and about the equipment condition to take and necessary action before breakdown of unit

-Rate of failure of the equipment,

-Frequency of its usage,...

-Criticality of the equipment in the plant...etc