In a recent discussion in the Linkedin group ASQ Reliability Division, John Pagendarm replied with his recipe for CRE exam preparation. With John’s permission, I’m posting here.
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.
Sign up for the CRE Preparation Notes email list for the new reliability engineering short tutorials.
- Improve your reliability engineering skills
- Learn about the wide range of tools available
- Enhance your resume with the ASQ CRE
You will find the most recent tutorials in reverse chronological order below.
When Are We Out of Control
For a stable process, nothing much happens. If the stable process is producing acceptable products, we should expect to continue to produce acceptable products.
Unless something changes. [Read more…]
2013 in Review
Thanks to you all for a great year. The idea of the blog is to assist those preparing for the CRE exam or wanting to learn about reliability engineering. It seems to have found the audience.
The WordPress.com stats helper monkeys prepared a 2013 annual report for this blog.
Here’s an excerpt:
The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 21,000 times in 2013. If it were a concert at Sydney Opera House, it would take about 8 sold-out performances for that many people to see it.
8 Steps to Creating an X-bar and s Control Chart
Once you decide to monitor a process and after you determine using an $- \bar{X} -$ & s chart is appropriate, you have to construct the charts.
The $- \bar{X} -$ & R charts use the range as an approximation of the variation in the population. When feasible use the standard deviation, s, rather than the range, R for the improved efficiency in detecting meaningful changes in process variation. [Read more…]
8 steps to Creating an X-bar and R Control Chart
Once you decide to monitor a process and after you determine using an $- \bar{X} -$ & R chart is appropriate, you have to construct the charts.
This is not difficult and by following the 8 steps below you will have a robust way to monitor the stability of your process. [Read more…]
Intro to Fault Tree Analysis
The NASA Fault Tree Handbook with Aerospace Applications
This is a break from the usual format of this site. I’m highly recommending that as your review materials and prepare for the CRE exam or prepare to conduct an FTA, you read this NASA document as an intro to fault tree analysis.
For a review, I suggest the first chapter or two. If working in the aerospace industry, you should print and use a copy.
The following is an extended excerpt from the first section of the document. [Read more…]
Variables Control Chart Background
What are Variables Control Charts?
From NIST Engineering Statistics Handbook, section 6.3.2, with edits and additions.
During the 1920’s, Dr. Walter A. Shewhart proposed a general model for control charts as follows: [Read more…]
Selecting Control Charts
Consider a handy flow chart and set of descriptions that will assist you in selecting the appropriate control chart, or at least understand the differences. [Read more…]
Statistical Process Control Overview
Basic introduction to key concepts of SPC
Statistical process control (SPC) is not a control chart alone.
SPC is a set of tools and a thought process to identify, measure, monitor and improve important elements of product development and production. I’ve seen very good and very bad implementations of SPC. [Read more…]
Norris-Landzberg Solder Joint Fatigue
Before Norris-Landzberg’s study there was the work of Coffin and Mason.
Coffin-Manson
One way to approach accelerated life testing is to use a model for the expected dominant failure mechanism. One such model is for solder joint low-cycle fatigue originally published by Coffin (1954) and Manson (1953), independently.
Norris-Landzberg
Norris and Landzberg proposed the plastic strain range is proportional to the thermal range of the cyclic loading (ΔT). They also modified the equation to account for effects of thermal cycling frequency (f) and the maximum temperature( T). They and other than empirically fit the parameters for the equation. [Read more…]
Accelerated Life Testing
A form of testing that reduces the time till results are known, ALT provides a means to estimate the failure rate over time of a product without resorting to normal use conditions and the associated duration.
For example, solar photovoltaic cells should operate for 25 years without failure. The product development time is less than a year for a new panel and the team wants to estimate the reliability of the cells over the 25-year duration. [Read more…]
Two question challenge
When this posts I should be home from Nepal and mostly recovered. So, back to more details going forward. Take a look, work the problem, solve it, then show your work. Comment with why you chose your response and why you didn’t select one of the others. [Read more…]
Reliability Modeling Options
When this posts I should be just getting home from Nepal (jet lag is no place to write posts). So, this post and the next couple are homework for you. Take a look, work the problem, solve it, then show your work. Comment with why you chose your response and why you didn’t select one of the others.
From question 19 of ASQ CRE 2009 sample exam. [Read more…]
Corrective Action Question
When this posts I should be near 17k ft altitude without electricity or internet – hoping for the best. So, this post and the next couple are homework for you. Take a look, work the problem, solve it, then show your work. Comment with why you choose your response and why you didn’t select one of the others.
Here is question 18 from the ASQ CRE 2009 sample exam. [Read more…]
Fault Isolation
I’m about to leave for Nepal for a month and much of it without internet. So, this post and the next couple are homework for you. Take a look, work the problem, solve it, then show your work. Comment with why you chose your response and why you didn’t select one of the others.
This is question 17 from the ASQ CRE 2009 sample exam. [Read more…]
