Your Reliability Engineering Professional Development Site
When a product or system fails, there is a consequence. Often, there is a loss of value. Each warranty replacement costs money. Downtime may result in lost revenue. Do you know the full extent of the costs involved when something fails?
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When we make a measurement, we make a decision based on the data provided. It’s important to have data close enough to the actual measurement. What is the measurement error if something is supposed to be 2 cm long and we measure it at 2.1 cm?
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Once a product is launched, it’s time to understand its performance. The design is done, and the assembly process is working. Now we can focus on answering the question: is the product hitting reliability targets or not?
Thus, we do field data analysis. [Read more…]
In a meeting the other day, the presenter was talking about a range of different failures for the product in question. She talked about each issue, a bit about the failure analysis, yet didn’t reveal which failures occurred more or less often.
She did provide a handout with a listing of the problems in order of the product field age and listing of the failure name (component or system involved). So, I grabbed a piece of paper to create a frequency table so I could quickly determine which problems occurred more often than others. [Read more…]
There are three approaches to setting tolerance limits for design elements. Each has ramifications for the eventual manufacturability and reliability performance—design for manufacturability and reliability hinges on correctly setting design tolerances. [Read more…]
The clever Dr. John Snow mapped cholera cases during the epidemic of 1854 on a street map of the area. This type of mapping now called a measles chart, or defect location check sheet, or defect map, is useful when exploring the effect of location data.
The name measles chart may have come from the habit of using an image of drawing of a product and adding small red dots to signify defect locations.
In brainstorming, you may face a large number of unique ideas even after affinity diagraming. Multi-voting is a great tool to gain consensus on the top priority ideas with your team.
For less than 10 or so items we could use a rank ordering method, yet that method becomes cumbersome when there are a lot of items to prioritize. There are a couple of ways to conduct multiple-voting. Mastering this technique will help your team quickly focus on what is truly important. [Read more…]
The survival of an individual item is difficult to determine. Use and environmental conditions, along with material and assembly differences, count. Let’s explore how to model and use the naturally occurring variability to improve reliability performance. [Read more…]
Years ago I was a part of a reliability engineering community and I had not met more than two or three members. This was before the internet and was using a new-fangled system called an email list.
At the time, it filled the role of helping me understand the many facets of reliability engineering. It helped me answer questions and allowed me to help others as well.
My desire is to help create more such communities that can help you and your organization improve the discussion concerning reliability. Let’s explore exactly how to make this work. [Read more…]
Received a question from a reader this morning that will make a nice tutorial.
A box contains 27 black and 3 red balls. A random sample of 5 balls is drawn without replacement. What is the probability that the sample contains one red ball?
So here’s my thinking and two ways to solve this problem. Instead of red and black balls in an urn type problem, which is pretty abstract, let’s say we know 3 bad parts are in a bin of 30 total parts.
Ran across this question the other day from someone just starting in the role of reliability engineer. I wasn’t smart enough to ask this question when I started in the field, yet looking back I’m sure to have found the list of what one should learn and apply daunting. [Read more…]
Also called the Ishikawa or fishbone diagram, the cause and effect diagram is a graphical tool that enables a team to identify, categorize, and examine possible causes related to an issue. The intent is to expose the most likely root causes for further investigation.
This diagram is part of a complex failure analysis process when there are many potential causes for the problem or condition. Similar to a brainstorm session about the problem, this graphical tool provides a bit of structure and may prompt additional potential causes.
The Ishikawa diagram is one of the seven basic tools of quality control. [Read more…]
Published in Quality Progress in Nov. 2018, pp 34-39. Final 1/27/18 Posted here with permission of Dr. Wayne Nelson and by his suggestion.
Schenectady, NY , WNconsult@aol.com
Sometimes a process doesn’t happen one step at a time. Sometimes, a problem we’re trying to solve has many moving and interacting elements.
Mind Mapping is a technique to capture those scattered thoughts, those non-linear processes, those myriads of interactions and dependencies. It’s a tool that is useful for brainstorming, organizing, and problem-solving. [Read more…]
There are two common uses for a check sheet. First, to summarize historical data, or second, to collect observations. A byproduct of creating a check sheet is team agreement on definitions of categories and observation procedures.
The investment is minimal other than thinking about how you want to view the data, and what data to collect. [Read more…]
