Preventive vs Reliability Centered Maintenance

Both preventive maintenance (PM) and reliability centered maintenance (RCM) are designed to increase asset reliability and lifespan by creating a system of scheduled work.

With each maintenance type, work is scheduled in advance depending on the type of asset. This work is then carried out according to the set schedule, with some work being being performed at consistent intervals (like months, years, or machine cycles). The main difference is the degree of uniqueness to the schedule. 

Preventive maintenance is often generalized across a large amount of assets, while reliability centered maintenance takes a deep and specific look at each individual piece of equipment to create a schedule unique to only that piece of equipment.

Both systems can be expensive in different ways. Preventive maintenance systems can be expensive due to their large scheduling needs, while reliability centered maintenance systems often have a larger upfront cost. However, reliability centered maintenance can decrease overall maintenance costs as it reduces inefficiency by creating a set of equipment-specific maintenance procedures.

Differences between preventive maintenance and RCM

	Preventive Maintenance	Reliability Centered Maintenance
Definition	Preventive maintenance (PM) is a type of proactive maintenance that keeps assets in good order by scheduling tasks at specific intervals or dates.	Reliability centered maintenance (RCM) is a process for figuring out the level of necessary maintenance for a specific piece of equipment and then designing a unique maintenance schedule.
Workflow
Trigger	Time	Based on individual asset needs (can be time, parameter, downtime trigger)
Cost	Low	Medium/High (startup cost)
Cost Savings	12% to 18% [1]	20% to 70% (dependent on implementation) [2]
Resources Needed	Maintenance software for scheduling Maintenance scheduler (for larger organizations) Preventive maintenance checklists	Maintenance software for scheduling (especially for unique pieces of equipment) Maintenance scheduler Preventive maintenance checklists More advanced maintenance programs like PdM/CbM Sensor equipment (determined by equipment types)
Pros	Better than reactive maintenance Generally easy to create and implement	Potentially most efficient maintenance strategy Lower maintenance costs
Cons	Risk of over-maintaining equipment Labor intensive	Large initial investment More difficult to see immediate savings
Use Case	An organization wants to decrease unplanned	An organization uses a complex asset that’s built

[1] Types of Maintenance Programs by the Department of Energy, O&M Best Practices Guide, Release 3.0

[2] The ROI of RCM by Plant Services