RCM: How to apply Reliability Centered Maintenance

RCM (Reliability Centered Maintenance) or MCC (Manutenção Centrada na Confiabilidade) was a strategy developed by the American Army when they were studying a way to keep their military equipment in operation for longer in a cheaper and more efficient way. Curious, right?

The concept involves a maintenance policy structured to choose the maintenance activities needed to keep the availability and reliability of any production process, in a way it reduces to a minimum the asset’s life cycle cost. In practice, it ensured such great results that over the years it evolved into one of the most efficient strategies for industries to apply to their equipment. But what did they find out?

What they realized and learned was that there is a difference between doing what has to be done and what can be done in maintenance. Several managers make a mistake when choosing, for example, corrective maintenance (can be done) for a piece of equipment of high criticality, when in fact what should have been done instead was predictive maintenance for that type of asset. That makes them spend too much money on maintenance and still doesn’t help them reach the desirable levels of availability and reliability in the process. RCM changes this scenario by choosing one strategy for each asset, aiming at preserving its function in a given process.

Ready to make your machines more reliable and available? For you to learn how to implement RCM in your installation, we created a simple step-by-step route to follow. But before, let’s learn a little more about the objective of reliability-centered maintenance.

The main focus of RCM

The main focus of RCM is to reduce as much as possible the LCC (life cycle cost) of the asset. Why?

The LCC is the sum of all costs with the equipment, from its specification, installation, operation, and maintenance until its decommissioning, uninstallation, and disposal. That means it gathers all the costs with a machine. Acting towards the LCC reduction, the reliability centered maintenance becomes one of the most profitable maintenance models that exist.

RCM is a careful process that allows you to choose objectively the most suitable maintenance strategy for each asset. Its implementation requires reliable data and analyses that allow sensible decisions.

This way, inside an RCM program the maintenance actions must have three basic objectives:

• Reduce or eliminate the chances of a failure occurring,
• Reduce or eliminate the severity of a failure,
• Increase the chance of detecting a failure at an early stage.

Now that we know where our strategy is heading, we shall move to the following implementation.

Steps to implement the RCM

A typical RCM process involves 6 steps. First, you select the equipment that will take part in the program. Then, you identify three categories, the functions, the functional failures, and the failure modes and effects of each of them. Lastly, based on what has been identified, you choose the maintenance tasks that prove to be the most favorable for each asset. After that, it’s just evaluating and revising the strategy because there’s always room for improvement, right? Now, let’s talk a little more about these steps.

1. Select the equipment

The team needs to list all the equipment and assets that are subject to the RCM implementation. The decision process normally involves many aspects, including safety, legal and economic considerations.

In this phase, make sure you add to the radar all the assets that you will wish to add to the program as if you could scan your installation as a whole. To make things easier, write the name and models of this equipment on a piece of paper or spreadsheet to prevent losing it in the future.

2. Identify the functions

In the second step, the RCM is already beginning to take shape and you need to identify the functions of each selected piece of equipment. That includes qualitative and quantitative descriptions of expected tasks. Then, what is the role of this or that piece of equipment inside the process?

If we take, for instance, a pneumatic press in the cosmetic industry, the function of this asset should be to press cosmetic materials and transform them into make-up, such as eye shadows, blush, and others. In terms of numbers, we could add up the quantity of eye shadow this piece of equipment produces per hour.

This step recognizes that each asset is part of a bigger subsystem. The understanding of each of the equipment’s functions leads to a broader overview of how the system works.

3. Identify the functional failures

After understanding what the asset’s functions are, we need to identify the failures that make it impossible for the equipment to continue performing its functions according to its production expected, which are called functional failures.

If we take, for instance, an electric motor, some of the functional failures could include:

• Disarming due to overcurrent
• Short-circuit damage
• Bearings damage
• Rotor unbalance
• Loss of starting torque

In other words, you need to list the facts that, if present, could lead to the asset’s stop/breakdown.

4. Identify the failure mode and effects

This process analyzes the conditions that can cause failures and connects them to the corresponding consequences. Therefore, one of the main points in this step is the Failure mode and effects analysis (FMEA).

The FMEA consists of analyzing the production process to identify failures that can affect that process, find the symptoms those failures present (failure modes) as well as their consequences (effects). To do so, there are three steps:

Point of failure:

In this step, you need to list the pieces of equipment that are vital for the best operation and, consequently, for the production process. For instance: gearing, bearings, retainers, among others. It would be interesting to create a table with three columns. In the first, include the name of the equipment, in the second, the function (both already mentioned), and lastly all these essential components.

Failure analysis:

Here is the heart of the FMEA and there are 3 essential questions for this analysis:

• Failure mode: How does the failure present itself? Which sense does it trigger (visual, hearing, smell or touch)?
• Failure effect: What is the consequence of this failure in the process?
• Cause of failure: What led to the failure of that component?

Let’s see an example:

• Failure mode: Shock of flanks (excessive vibration)
• Failure effect: Disarming of electric motor
• Cause of failure: Lack of adjustment in the Back Backlash

After answering these questions, you begin to understand how each part of your equipment is important for the process and how the effect can be catastrophic if a problem occurs. For that reason, attention to every detail in each piece is important.

Risk assessment

After that, all you have to do is quantify. The risk assessment takes place considering three factors:

• Occurrence of failure,
• Severity of failure,
• Probability of detection.

For each of the three items above, give a score from 1 to 10 and the multiplication of these three scores will add up to the RPN (Risk Priority Number). 

The higher the RPN, the more attention and priority we should give to that given point in the process.

5. Select the maintenance tasks

Based on the previous steps, now you have a better idea about which assets need more attention. Now the action should focus on minimizing or even eliminating the risks of stops in production, assigning maintenance tasks that increase your functional operation. They are:

• Corrective maintenance for non-critical items and without consequence and risk for the process: Consists in all maintenance actions performed after the failures, being potential or functional.
• Preventive maintenance for worn items and known failure patterns: Consists in all maintenance actions performed to reduce the probability of the occurrence of a potential failure, such as inspections and replacement of pieces due to usage time.
• Predictive and detective maintenance for random failures and items of high criticality: Consists in the monitoring and tests aiming at identifying and quantifying the severity of potential failures at an early stage. In this type of maintenance, it’s necessary to collect and process the equipment’s data, with analysis of the vibration level, temperature, noise, flow, among others.
• Proactive and prescriptive maintenance for failure analysis, root cause, and commissioning of equipment: Consists in the  continuous optimization of the process and all equipment through the experience acquired with the events of failure and/or maintenance. When you already have a consistent amount of data about the assets, understanding your equipment’s special patterns becomes possible.

6. Evaluate and revise

Evaluating and revising your RCM process helps to reveal opportunities for improvement. This step can be executed through detailed discussions with specialists in the matter. Experience and personal accounts of events from different members of the team can also be gathered to evaluate the performance of the current processes.

Alternatively, mock-ups can be performed to speed up the evaluation process. Hypothetical situations can be taken to the current setup in order to gather information on how the system reacts. The mock-up data contains valuable information for potential improvements.

Tractian can help you with predictive and proactive maintenance. We can provide from the equipment’s data collection to the processing and generation of insights for your maintenance team. For more information, send us a message using the pop-up below. Our team will be available to answer your questions.