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Prep notes for ASQ Certified Reliability Engineer exam ISSN 2165-8633
The CRE Preparation Notes series provides you with short practical tutorials on all the elements that make up the ASQ CRE body of knowledge. The articles provide introductory material, basics, how-tos, examples, and practical use guidance for the full range of reliability engineering concepts, terms, tools, and practices.
Keep your knowledge fresh by regularly reviewing topics and tools that make up reliability engineering.
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You will find the most recent tutorials in reverse chronological order below.
When people hear ethics, they often think of formal codes of conduct, professional standards, or exam topics. In reliability engineering, ethics is usually much more practical – and sometimes uncomfortable.
Ethical issues rarely present themselves as clear right or wrong decisions. They tend to appear as trade-offs, pressures and grey areas, often under time, cost or schedule constraints.
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The role of the reliability engineer is often associated with specific activities or phases of the lifecycle, such as prediction during design, testing during development or data analysis in-service. In practice, reliability engineering is a through-life responsibility, even though its focus changes over time.
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Reliability engineering is viewed by many as a technical discipline focused on analysis, modelling, and prediction. While those skills matter, they are only part of the role.
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Reliability, safety, and quality are commonly considered separate disciplines, each with their own people, processes and tools. In practice, they are deeply interconnected and decisions made in one area almost always influence the others, particularly once systems are in service.
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Reliability, Availability and Maintainability are often discussed together. While closely related in practice, they are not the same thing and the distinctions are not always well understood.
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Many people associate reliability engineering with metrics, and while they can be helpful when used correctly, they are not the primary benefit of reliability engineering. The real value lies in the thinking and decisions that shape those numbers.
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When people hear the word reliability, it’s often interpreted as meaning “zero failures”. While that’s understandable, it’s not what reliability engineering is really about.
The Certified Reliability Engineer (CRE) Body of Knowledge, produced by the American Society for Quality, defines reliability as:
“The probability that an item will perform a required function without failure under stated conditions for a specified period of time”
Crucially, each part of this definition needs to be clearly understood and agreed from the outset, particularly between customers and suppliers. Many reliability problems arise not because the definition itself is wrong, but because these elements are interpreted differently.
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When working with a team creating a new system, I always ask, “what is the goal?” The answers often do not make much sense. The team using SMART reliability goals are astonishingly well-stated.
The difference that makes a goal, objective, or requirement practical and useful is summed up by SMART. A SMART goal is Specific, Measurable, Achievable, Relevant, and Time-bound. Let’s explore each element as related to a reliability goal.
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One of the very first plots to do with a string of data is a simple run plot. This plot provides information related to location, trends, patterns, and anomalies, The plot of the data over time is a rather informative chart.
You have most likely constructed many run charts; if not you really should. This short introduction to the run chart will cover creating and interpreting them. Plus we’ll mention a few cautions and tips, as well. [Read more…]
Stratification implies layers or differences. A quick test for soil composition is to place a sample of soil with water in a clear jar and give it a shake. The sand, silt and loam will settle at different rates and create a layered appearance within the jar over time. The height of each layer provides information about the proportion of each type of soil within the sample.
Stratification as one of the seven basic quality tools (some lists use a run chart or flowchart instead) the idea of layers or differences still applies. The idea is to identify potentially meaning differences within a sample set. [Read more…]
A histogram is a graphical representation of a set of data. It is useful to visually inspect data for its range, distribution, location, scale, skewness, etc. There are many uses for histogram, there you should know how to create one.
Let’s explore a set of data and create default histograms using a variety of methods. If you have a way to create a histogram using some other method or software package please send it over and we’ll add it to the article. [Read more…]
In the situation where you have a sample and would like to know if the population represented by the sample has a mean different than some specification, then this is the test for you. In this case, you do not know the actual variance of the population, you just have a sample.
This test is often the second one in a textbook that describes hypothesis testing. It is a useful hypothesis test and applies in many situations as we rarely know the population variance. [Read more…]
One of the key ideas behind the ASQ CRE certification is the need to learn enough to pass the exam. Then you are expected to continue to learn to maintain your certification. It is the key idea of ongoing professional development that central to the CRE program, and many other certification programs.
Over this past year of COVID-induced restrictions, the ability to attend local chapter meetings or conferences has changed. While many events are now done online, it’s another Zoom meeting after a day full of such online meetings.
A recent article by Anant Agarwal, the founder and CEO of edX titled, “What I’ve Learned About Learning – 5 Hacks for Success” caught my attention. Anant provides a few tips to improve your online learning – and I would say any learning. A little research on how to best learn online also found “Tips for Successful Online Learning” that helped inform this short summary. [Read more…]
One of the first things to do when faced with a set of numbers is to plot them. A histogram is often the first choice, maybe a dot plot. Up your data plotting skills and let your data provide a bit more information by using a box plot. [Read more…]
As reliability professionals, we are in the business of estimating or forecasting the reliability performance of our product, equipment, or system. While we use a range of tools to analytically make these estimates, sometimes we do not have sufficient data or information.
One method is to ask another person that has knowledge of the particular technology, use conditions, or whatever is hampering our work. If you ask two people you most like will get two different answers. If you ask 10, 10 different answers.
One way to work with a group of subject matter experts is to conduct a structured communication technique called the Delphi Method. [Read more…]
