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CRE Preparation Notes

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.

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Z Value

Z Value

A skill needed for the CRE exam is the ability to look up probabilities given a z-value using a standard normal table. It’s old school, I know, yet without software, you most likely will have to find a few values in this manner.

A z-value is the number of standard deviations from the mean at least that’s how I think of it. The area under the curve to the right or left of the z-value is then the probability of interest. Of course, I’m talking about the normal distribution probability density function or what we commonly all the ‘bell-shaped’ curve. [Read more…]

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Reliability Centered Maintenance

Reliability Centered Maintenance

The document by Nowlan and Heap

Part of keeping equipment operational is affecting repairs appropriately. Sometimes it makes sense to replace an element of some equipment before it fails, i.e. automobile tires as the tread wears. Sometimes is doesn’t make sense to repair a functioning unit as the result would be a system that is less reliable then before. [Read more…]

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CRE Exam Preparation

CRE Exam Preparation

I never did like taking final exams in college as I viewed them as four hours I would rather spend doing something (anything) else. An exam is a check of what you know about a topic or subject. We prepared for those exams by reading, studying, practicing working problems (doing homework) and trying to understand the key concepts, trends, themes, etc. Some of my classmates thought it was about how much they could stuff into short term memory, others though sleep deprivation had something to do with preparing for an exam. [Read more…]

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Sample Size Problem

Sample Size Problem

Let’s work a sample size problem.

A random sample size, n, is to be taken from a large population having a standard deviation of 1″. The sample size is to be determined so that there well be a 0.05 risk probability of exceeding a 0.1″ tolerance error in using the sample mean to estimate μ. Which of the following values is nearest the required sample size?

a. 42

b. 106

c. 203

d. 384 [Read more…]

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Websites for Reliability

note: if you know of a great online resource that isn’t on this list, please add a comments and we’ll add it to the list for all to share.

Shon Isenhour recently posted on Linkedin a question about online resources helpful for reliability engineers. I added my list and hadn’t seen any other links added. There must be more than the few I know about – what can you add to this list? [Read more…]

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Dependability

Dependability

Ran across an interesting graphic in a new book recently. It single-handedly placed dependability in its proper context. It is an umbrella term that includes most of what we commonly think of as reliability and the other ‘ilities.’ It encompasses the various connotations of dependable and reliable that are conveyed during common use. And, the term dependability permits the overarching context for defining very clearly the various [Read more…]