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If you have been working in maintenance for a while, RAM analysis is part of your routine and you have certainly heard and talked a lot about the concepts that make it up: Reliability, Availability, and Maintainability.
Each one of these indicators has a certain function, and we are going to explain all of them and their respective formulas in this article. But before you read any further, be aware that it demands your full attention: RAM analysis is the main pillar of Maintenance Engineering and its indicators allow us to extend equipment lifetime, prevent failures and reduce maintenance costs, thereby improving the company’s productivity, profitability and competitiveness.
In the following topics, you will learn more about how to measure your maintenance results and, most importantly, how to improve them.
We have already mentioned that the acronym RAM stands for Reliability, Availability and Maintainability. But what are the goals and the benefits of this type of analysis? And how do we implement it?
Let’s take it one step at a time. Basically, the goals of RAM analysis are to decrease maintenance and operation costs, improve productivity and consequently increase the organization’s profitability. RAM evaluates system performance by measuring the number of machine failures, the time between these failures, the time to repair them, and other metrics.
Knowing that this analysis uses calculations and numbers to evaluate the equipment, we may conclude that the results measured by the three RAM concepts, depending on their formulas and requirements, must always be expressed in quantifiable terms. An example is the reliability calculation, which, as we will see in the following topic, corresponds to a percentage that indicates the right functioning of the equipment for a certain time, usually measured in hours.
Before moving on and digging more deeply into the indicators of this analysis, remember that RAM is a rigorous assessment that should not allow any misinformation – the registers, whether manual or digital, should always be impeccable and impossible to generate wrong interpretations, since this affects the entire production chain. No wonder that, more than ever, technological tools such as maintenance softwares have become great allies of maintenance, since they automate this work as they measure the indicators in real time and instruct the team about what should be done.
The first letter of the RAM analysis represents the probability of the machine performing its function – specified by the project and under the operating conditions – for a given period of time. And this probability, which takes into account failures that have already occurred, tells the maintenance manager how much he can trust that equipment.
Reliability can be measured using a range of tools, including the following ones:
But the truth is that the greatest ally of the maintenance manager when it comes to measuring the reliability of a machine is the MTBF (Mean Time Between Failures). This is one of the most important indicators in the entire maintenance field. It measures the average number of hours (or other unit of time) that a repairable equipment works properly between failures, excluding scheduled downtime.
Naturally, the longer the average time of good performance, the more reliable the system is, since the devices are taking longer to fail. But if we want to be more specific and know the probability that an equipment will work perfectly next week or next month, we use the reliability calculation:
Once we have identified the MTBF and the reliability of each item, we can schedule the inspections and other preventive maintenance activities in our plan. And it is very important to always try to improve the reliability of the plant, which is the main goal of the Reliability Centered Maintenance (RCM) strategy. Learn more about this extremely cost-effective maintenance approach in this TRACTIAN article.
Before moving on to the next topic, take a moment to think about how your team collects, calculates and interprets the indicators mentioned above. If you have been working in maintenance for some time, you surely know the importance of always keeping the data concerning the essential indicators at hand, and recording them in the most accurate and understandable way possible.
Therefore, considering the principles of RAM analysis, it might be the smartest and most strategic option for your maintenance plan to abandon computer spreadsheets (which are often not accessible to everyone and can contain errors) and replace them with online monitoring tools. Nowadays, thanks to technological advancements, there are maintenance management softwares – such as TRACTIAN – that monitor the machines in real time, calculating their individual MTBF and reliability and sending insights based on these analyses to the manager.
By using a solution like this one, you let the staff focus on more effective activities than manual data collection, and ensure that the most important indicators for the maintenance plan are always up-to-date and error-free – preventing the headache of unreliable machinery that often affects managers.
Unlike reliability, availability is concerned with the past and refers to the length of time that the device has been available to perform its specified functions. In other words, it is the capacity of an equipment to perform its designated role for a certain period of time.
When calculating availability, we compare the number of hours the machine was available with the number of planned working hours (these, in turn, are obtained by adding uptime and downtime). This calculation is based on two important indicators: MTBF, presented earlier, and MTTR (Mean Time To Repair), which analyzes the average time it takes for the team to repair the machine. To estimate this time, just add up the repair hours and divide it by the number of interventions that have been performed.
After that, you apply the obtained values to the formula below to find out the availability rate:
While reliability indicates how much we can rely on the equipment to work properly and availability shows whether it can be used, maintainability is about how easily we can repair the machine and return it to its normal function after a failure.
The M letter of RAM analysis is focused precisely on eliminating obstacles and difficulties in the technicians’ actions and maintaining the good performance of the machine. After all, the more difficult it is to repair the equipment and return it to its proper functioning, the lower the maintainability is – leading to higher maintenance costs, impacts on the company’s productivity, and headaches for the manager.
We have a high maintainability when the mean time to repair – the so-called MTTR, as we have seen before – is low, meaning that the machine takes a short time to return to its productive state. In other words, improving the MTTR means improving the maintainability and, likewise, the availability of the equipment, since the mean time to repair takes part in this second assessment as well.
Differently from the first two components of the RAM analysis, maintainability is not necessarily quantifiable and requires a more human evaluation that considers, besides costs, some critical aspects for the maintenance team’s work, such as:
When it comes to ways of improving this indicator, they do not differ from those mentioned when we talked about reliability and availability. Companies that adopt systems based on data science and artificial intelligence to predict failures increase the maintainability of their machines and save money on maintenance, as they are spared from unnecessary inspections and corrections.
We must remember that one of the objectives of RAM analysis is the removal of obstacles that the staff faces during interventions. Therefore, what could be more effective than choosing predictive maintenance as the star of the maintenance plan? After all, there are no difficulties in repairs that, thanks to early failure detections, never had to be done.
You already know RAM analysis, its goals, benefits, and formulas – now all you have to do is apply this knowledge to your maintenance plan and improve your indicators.
We have discussed this matter before, but it is worth remembering: it is crucial that the reliability, availability and maintainability of your company’s equipment are measured constantly and rigorously, so that the data collected is always accurate and impossible to be misinterpreted. Only then it will be possible to deeply know your machinery and its maintenance, improving your processes to the utmost.
And, of course, if you are ready to leave the spreadsheets behind and want to ensure that your machines are always reliable, available, and easy to assess and repair, you can count on TRACTIAN.
Sobre o Autor:
Industrial Designer by UNESP (State University of São Paulo). He specializes in product design with an emphasis on digital manufacturing, innovation and communication. Contributing to the creation and relevant content for industry. Head of Marketing at TRACTIAN.
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