What is Predictive maintenance(PdM)? What is the difference between Preventive and Predictive maintenance?

What is Predictive maintenance(PdM)?

Predictive maintenance is conducted on the basis of data collected on the machine condition. The predictive maintenance is a set of activities that detect the physical changes in the equipment that may cause failure.

To be effective, the machine being monitored must be sufficiently instrumented to obtain meaningful data. Monitoring means collecting, storing and analyzing the data. This maintenance program sets the limit or alarm that indicates when the fault is near and maintenance is required.

The monitoring of the condition depends on selecting the correct combination of parameters that coincide with the expected faults and the use of the correct measurement technique, the location interval and the processing, it is also important to record enough information to be able to carry out the monitoring and the diagnosis.

There are two types of monitoring, monitoring carried without the interruption to the operation of the machine. Monitoring which requires the shutdown of the unit, or at least the releases of the machine from its prime duty.

It is classified into two kinds according to the methods of detecting the signs of failure:

  • Condition-based predictive maintenance: depends on continuous or periodic condition monitoring equipment to detect the signs of failure.

  • Statistical-based predictive maintenance: depends on statistical data from the meticulous recording of the stoppages of the in-plant items and components in order to develop models for predicting failures.

Difference between Preventive and Predictive maintenance:

The combination of preventive and predictive maintenance can give the best maintenance program.

  • The main difference between preventive maintenance and predictive maintenance is that predictive maintenance uses monitoring of the state of the machines or equipment to determine the real mean time of failure, while preventive maintenance depends on the average industrial life statistics

  • Predictive maintenance is initiated based on period of time, event and meter readings, while preventive maintenance is done based on the actual machine condition.

  • Predictive maintenance use advanced technology such as infrared thermal analysis, vibration analysis etc for finding out the faults. Preventive maintenance is based on time and the breakdown rates of similar parts.

  • Predictive maintenance has more internet access and cloud storage facilities.

  • The drawback of predictive maintenance is that it depends heavily on information and the correct interpretation of the information.