MRO & RCM, based on my understanding.
What is MRO, I thought it is the abbreviation of Maintenance, Repair and Overhaul, but there are some who insisted that it is Maintenance and Repair Operation and some Maintenance, Repair and Operation. Whichever it is, in layman term it basically is about Maintenance services to keep facility, system, and/or equipment in safe and reliable operational condition, at a reasonable cost and with minimal downtime incurred.
MRO normally will be associated with Reliability Centered Maintenance (RCM). RCM sound like a motherhood statement, I mean why have maintenance services if is not catered for reliability? So what is RCM? Sound to me like a term some academic coined to package all known Maintenance strategies and sell it at corporate level as a concept of Total Maintenance of sort. Anyway, joke aside, I am not an academic or expert, but I had been working in maintenance line long enough to know some basic of maintenance strategies and its development, and would like to share my understanding in layman term.
MRO regime, process and strategies were created and evolved through needs, analysis and experiences, ultimately to control cost incurred through logistics needed, and production or revenue loss because of downtime. In the early days, most machines were repaired as and when they broke down. Experiences and studies had shown that in this form of reactive action, aka Corrective Maintenance (CM), when it happened to critical machine, system or part, it could be costly, or even disabled production capability and in some cases may endanger human life.
Preventive Maintenance (PM) was thus developed. It is based on knowledge and estimation of the durability of component that were subjected to degradation through wear, tear and fatigue deterioration and to get them replaced or repaired on a regular interval. Though preventive maintenance is effective for its purposes, it can be rather costly and incurred stoppage time. Most stakeholders tend to schedule their preventive maintenance accordingly to the Original Machine Manufacturer (OEM) recommendation. But OEM recommendation most of the times, were seen as excessive, because parts were recommended to be renewed well before it need to be and sometimes more frequent than needed. Guess it is partly to stay on the safe side, avoid liability issue and partly for commercial gain, because they were also the replacement part suppliers.
To minimise cost involved in PM, stakeholders sometimes analysed the component replaced and gauged their serviceability condition for possibility of rescheduling PM to further date or to cut down it frequency. Sometimes stakeholder might try to lower maintenance cost by getting parts from aftermarket supplier when they deemed that the OEM marked up is hefty. This usually is done after the warranty period, and there should be governing system to control and record such activities to ensure the compatibility of aftermarket parts, and to revert if problem surfaced later.
As machines became more complex and sophisticated, parts that require replacement increases and/or became more expensive, especially so for those that were termed proprietary. Stoppage time for preventive action could become longer and/or more frequent. To overcome this, Predictive maintenance (PdM) strategy was thus developed. It aims to optimise the use of the machine and its parts. It is usually done by monitoring the machine performance and condition through periodical inspection and examination for symptom of anomaly (most commonly through vibration or temperature data) and intervene or schedule to intervene before the estimated imminent failure.
With advancement of technology, the prediction was enhanced with equipment capable for monitoring and assessing the real time condition to detect early stage of failure and relayed it to the maintenance service base through WIFI or online connection, and arrangement can be made to arrest it before it matured into a breakdown. This is termed as Condition based Maintenance (CbM). It is more accurate, and is capable to arrest imminent failure at subcomponent level, but the setup may be costly.
Then with advancement in digital technology, real time, historical data collection could easily be compiled and analysed, using software for Failure Modes and Effect Analysis (FMEA) and Root Cause and Failure Analysis which further enhance the prediction of imminent failure, to enable proactive maintenance. Systematic elements relating to failures were examined to identify area where scheduled PM did not cover and create a maintenance program that maintenance is carried out to resolve problem before it become a failure, only when necessary.
The concept of maintenance program that include all the above-mentioned strategies is eventually termed as Reliability Centered Maintenance (RCM), which is a corporate level strategy that aims at doing the minimum level of maintenance to achieve maximum availability (i.e. uptime for production or revenue services) with assured safety and reliability. It may incorporate computer maintenance management software or FMECA (Failure Mode Effect and Criticality analysis) methodology to identify critical failure mode and it effect systematically for the whole system or equipment, then down to the last component. Maintenance strategy is then decided according to the risk priority and failure impact rank by the analysis. Simply put: Component which had little or no functional impact, do not have defined life span, and costly to monitored may simply be allowed to run to failure, i.e. reactive maintenance, aka CM. Regular component that is subjected to systematic degradation based on usage or aging may be assigned with scheduled PM at determined interval. Predictive maintenance will be used to optimise the use of more costly component and which replacement may need longer downtime. For costly equipment that failure impact is severe, and which incurred long downtime to replace, condition based monitoring will be considered.