Introduction

There are many best practices (sometimes referred to by their buzzwords or acronyms) to choose from when it comes to maintenance and reliability (M&R), whether they be maintenance approaches/strategies (predictive maintenance, preventive maintenance, run-to-failure, etc.) or maintenance processes (planning and scheduling, total productive maintenance, maintenance logistics, etc.).

Very few leaders in the M&R community would speak against any of these best practices. In fact, many of us in this community have an “all of the above” attitude when it comes to implementing M&R best practices; just choose which of these “tools” apply to your M&R and use those that make sense to you.

A couple of the buzzwords or acronyms used over the years are reliability centered maintenance (RCM) and failure modes and effects analysis (FMEA). Some in the M&R community will continue with the approach of do both of them, while others will contend that one is better than the other.

This article seeks to understand the differences and similarities between these two maintenance approaches/strategies and attempts to answer the question of whether RCM or FMEA.

RCM - Reliability Centered Maintenance

Reliability centered maintenance (RCM) is a reliability tool that is used to ensure the inherent designed reliability of a process or piece of equipment through the understanding and discovery of equipment functions, functional failures, failure modes and failure effects. In performing a RCM analysis, the RCM team uses a structured decision process to develop mitigating tasks for each failure mode identified during the analysis.

Like failure modes and effects analysis (FMEA), RCM can be performed in the design phase of a project. It is most commonly performed on existing equipment to develop a complete maintenance strategy in the hope of improving and sustaining the reliability of the asset.

While at first glance the two tools may look similar, there are some very distinct differences that will result in your effort coming up short should you use one in place of the other.

In addressing equipment functions, it is a requirement of RCM to address not only the function of the asset, but the performance standards we must maintain as well. FMEA functions are most often written at a higher level and do not address performance standards.

RCM failure modes are written at a more detailed level, addressing the part, problem and specific cause of failure (fuel pump motor bearing > seized > due to lack of lubrication). The detail of RCM failure modes is necessary to discover the correct mitigating task. FMEA failure modes are written at a much higher level (fuel pump motor will not run) and are written at this level because the FMEA process was designed to asses risk in the design phase.

RCM uses a structured decision process to determine a task to eliminate, detect, reduce the frequency of occurrence, or reduce the consequence of each specific failure mode. In doing so, the output of the RCM analysis becomes a complete maintenance strategy that is designed to ensure and sustain the inherent designed reliability of the asset. FMEA was not designed for developing maintenance tasks; it instead looks to mitigate risk of a failure mode through a recommended action that would occur in the design phase of the asset.

A good RCM process also addresses what should be done if there is not an applicable or effective maintenance task or redesign to address each failure mode. Here we look to reduce failure consequences’ mean time to restore (MTTR) by identifying and implementing consequence reduction tasks (detailed job plans and spare parts assessment). This is not addressed as part of FMEA.

RCM was designed to discover and assess all types of failure modes, including failure modes that consider the operating context and environment, as well as process-based failure modes. As a result, it is important to understand that the best RCM facilitators are certified in a given methodology. This certification ensures the facilitator has both knowledge and experience in the RCM process and has the same level of understanding and experience in maintenance techniques and methods (predictive and preventive). FMEA, on the other hand, is an engineering tool designed to reduce risk before we install the asset.

FMEA - Failure Modes and Effects Analysis

Ramesh Gulati and Christopher Mears

The Challenges of RCM

Reliability centered maintenance (RCM) has been in use for many years, but is used more frequently as a structured, programmatic approach to improving an organization’s maintenance program from a reliability perspective. The challenge is whether this structured, programmatic approach is a supporter or detractor to full implementation of the RCM approach.

In recent years, RCM has become a buzzword. Everybody wants to jump on the bandwagon and they want to do RCM. Many management executives, who have heard the name RCM, think RCM is a panacea for all their maintenance problems. They believe if they do RCM, it will resolve all their problems and their equipment will automatically become more reliable. In fact, several studies have indicated that the majority of RCM programs fail, either in the lack of implementation or in not achieving the expected benefits. It’s not that RCM is bad; it’s how it gets implemented, including the necessary buy-in from not only management but, even more importantly, the workforce.

Many organizations tried to implement RCM in the 80s and 90s and never truly succeeded. Many found that the perception about RCM was one of the biggest challenges. RCM was perceived and inappropriately portrayed to be a cure all for maintenance ills. Some of the RCM subject matter experts (SMEs) insisted on doing a full FMEA, looking for all failure modes (down to a single non-critical screw), which obviously takes quite a bit of time and resources. In some cases, a RCM analysis is not a good fit since it may be obvious what the maintenance strategy should be (just run-to-failure).

Another challenge of RCM is the perception that it’s just another program. With all the various programs over the years -- total quality management (TQM), quality circles, Six Sigma, lean and many others -- many organizations did not grasp that RCM is a living process. Instead, they thought it was just another program-of-the-month. Therefore, they gave it lip service while they did it, halfway implemented the changes, and reverted back to their old ways of doing things once the RCM consultant left or the higher-level manager moved on to bigger and brighter things. Since many organizations touted RCM as a program and ran it like one, complete with a program/project manager, RCM went the way of many programs (out the door).

Other organizations have taken a different approach. After a few failures and several successes in implementing RCM, they learned that you can’t enforce RCM in its purest sense or classical form as recommended by some consultants. What we are after is to keep equipment running – maintaining its functions at an optimal cost. Instead, they perform streamlined RCM or PM optimization efforts to improve the maintenance program. Sometimes, they perform FMEAs on groups of different types of equipment to get the most bang for the buck. And still others don’t call it RCM (due to the bad taste in some people’s mouths) and focus on the FMEA portion of the RCM process as a major tool in changing their maintenance program for the better. Doing these things typically cost less and show more benefits for organizations.

The Benefits of FMEA

Failure modes and effects analyses have been in use for many years in the M&R community because of their effectiveness and exhaustive application across many industries, as well as phases of the product, asset and facility lifecycles.

The basic process involves a number of major steps to complete a value-added FMEA, regardless of the type or purpose of that FMEA. In addition, there may be multiple minor steps within each of these major steps. Once a FMEA team has been established, the first step is to scope the FMEA effort, which provides a greater likelihood of successfully completing it. Next, the team defines the interfaces of the focused FMEA effort so the effects can be identified. Then the major components of the FMEA focus are defined (and broken down further as needed), along with each of their failure modes, root causes, failure indicators, failure criticalities, failure probabilities and effects using both team member experiences with the FMEA focus area as well as any available failure history. Some of the more traditional FMEA efforts stop here. However, we have seen the more effective FMEA efforts take this analysis and add to it the mitigation tasks and frequencies for each key characteristic candidates and identify the selected mitigation tasks to implement, ensuring that the selected mitigation tasks actually provide value by either detecting failure at the start of its failure mode or preventing a failure from occurring in the first place. The key to success of this FMEA process is in its application – only applying the individual step, as well as the detail of this step, as needed for the specific FMEA effort.

Probably the most common use of FMEA is for maintenance strategy development for a specific piece of equipment, product line, or facility. The preceding steps are used to identify the most likely failures, not necessarily all the failures. Of course, the number of failures within this analysis is dependent on th criticality of the FMEA focus. Once the appropriate mitigation tasks have been selected, formally documenting these tasks has proven to be a key factor to a successful implementation of the tasks. This formal document is the basis for an optimal predictive maintenance (PdM) and preventive maintenance (PM) plan. This optimal maintenance plan should identify any maintenance tasks currently being performed since this will impact the implementation plan. Finally, this formal document should also include any spares or specialized training needed for personnel (operations and maintenance) to execute the maintenance plan. The more formal this document is in your organization (for instance, an ISO-certified process document), the more likely the document will be followed once implemented. This document should become a living one, as should FMEA, in order for the overall maintenance program of that organization to be successful.

Over the last few years, organizations have started to incorporate FMEA as an integral part of capital investment and other design efforts. Although the use of FMEA in this part of the overall lifecycle approach to equipment and facilities has been occurring for only a short amount of time, the fruits of a FMEA look at equipment during the design phase are already reaping benefits and enabling long-term asset health, especially in ever-shrinking budget environments. Benefits of FMEA have been seen not only in reducing the potential for failures (reduced number of components and moving parts), but also in the introduction of PdM technology opportunities (including installation infrared windows in motor control cabinets equipment design) and right-sized optimization of the maintenance program (both PdM/PM and proactive run-to-failure decisions). Just as it is with maintenance strategy development, choosing the correct level of FMEA for a particular design is important in having a cost-effective design process with a maintenance flavor.

reliabilityweb.com

Conclusion

This article explores the differences and similarities between a RCM approach and a FMEA approach. In the end, it really is not a question of either/or. As you can see from this article, both approaches can be effective and can stand on their own without the other. The best approach really is an “all of the above” type approach. This allows you to select the most appropriate tools from each approach, as well as decide whether a formal program will benefit implementation of either approach or carries with it too much stigma of program failures of the past. As with all M&R best practices, education throughout all parts of your organization, implementation team, management team, and most importantly, those who will use it in the end, is your best strategy. Then let your newly-founded experts determine which approach best fits your organization.