How to Judge a Reliability Book

How Do You Judge a Reliability Book?

By it’s cover no doubt. The title and cover are important, this is true. When you judge a reliability book we often first see and evaluate the cover.

The author? Do you buy the book based on who wrote or edited it?

Do you have a quick scan or check for key features before you add the book to your library? I’m curious how you select a book to use a reference for your work. The books we read and use for work shape our work, thus it’s important to have the right works at our disposal. [Read more…]

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The 3 Best Reasons to Use MTBF

This may seem an odd article for the NoMTBF site. Stay with me for a moment longer.

Over the years of speaking out on the perils of MTBF, there has been some push back. A few defend using MTBF. Here are three of the most common (maybe not exactly the best, per se) reasons to use MTBF. [Read more…]

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MTBF Search Result Sadness

A Quick MTBF Search Reveals Distressing Results

I was preparing to write this article and wondered how many search hits would appear for MTBF? So, opened Google and did an MTBF search. It is a common if misunderstood, acronym.

Beyond the 5,200,000 Google search results, it was the first page results that got me thinking. Keep in mind that Google often serves up a combination of what it thinks you are seeking and which sites have been useful for others.

Let’s break down what you find when you do an MTBF search. [Read more…]

by Kirk Gray Leave a Comment

For Maximum Test Value, Take it to the Limit!

When we go to an automobile race such as the Indianapolis 500, watching those cars circle the track can get fairly boring. What is secretly unspoken is that everyone observing the race is watching for a race car to find and sometimes exceed a limit, finding a discontinuity. The limit could be how fast he enters a curve before the acceleration forces exceed the tires coefficient of friction, or how close to the racetrack wall, he can be before he contacts it and spins out of control. Using the race analogy, [Read more…]

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Why do we talk about reliability?

To make decisions
To estimate reliability
To understand risk

#182062550 / gettyimages.com

We talk about reliability because it matters. The ability to estimate reliability allows us to make design and development decisions. The ability to monitor reliability allows us to adjust the design, suppliers or expectations about a product. [Read more…]

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Reliabilty Predictions

Who are you fooling with MTBF Predictions?

All models are wrong, some are useful. ~ George E. P. Box

If you know me, you know I do not like MTBF. Trying to predict MTBF, which I consider a worthless metric, is folly.

So, why the article on predicting MTBF?

Predicting MTBF or creating an estimate is often requested by your customer or organization. You are being specifically asked for MTBF for a new product.

You have to come up with something.

[Read more…]

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MTBF Logic

The reason so many use MTBF is because so many use MTBF. ‘Our data sheet has to include MTBF since all the other data sheets have MTBF’. Which seems to be primary reason MTBF is so common. It’s because it is so common.

Against this logic is the desire I have to use a measure of reliability that actually is understood. Using reliability (probability of success over a specified duration) as a measure seems some how odd or novel. It is easy to understand and it doesn’t obscure the reliability. [Read more…]

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Marketing and MTBF

A few weeks ago I was working on a report summary that included a reliability value at 5 years for a product. The document was intended for use with customers, so it was reviewed by Marketing.

Not too many changes, which was nice as I do not consider myself a writer and certainly not a marketeer. They did ask for one change that prompts this note. They wanted the 96% reliable at 5 years to be replaced with the (roughly) 2,100,000 hour MTBF value instead. [Read more…]

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The MTBF Battle Continues

This site is part a long string of attempts to eradicate the improper use of MTBF. This week two people have sent me references to work previously done and Chris sent me another podcast also highlighting issues with MTBF. Jim McLinn wrote about the possible transition away from constant failure rate [Read more…]

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Wrong Conclusions

Here is a podcast by Chris Peterson of H and H Environmental Systems which includes her thoughts on the MTBF topic. She also explores how making even ‘obvious’ assumptions may lead to the wrong conclusions.

[soundcloud url=”http://soundcloud.com/handh-testing-lab/aug-7-podcast-using”]

Chris records a podcast almost everyday and many are enjoyable, fun, and and provide something to think about as you go about your day. If you like the podcast above, check out her growing list of available podcasts.

Embedded podcast with permission of Chris.

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Datasheet MTBF

Some many years ago I ran across a data sheet for a cooling fan (used to cool a desktop computer, for example) that listed the fan’s life as 50,000 hours MTBF. The big bold lettering was on the data sheet and was the only use of bold on the entire data sheet. One couldn’t miss it. The computers we used these fans within had a one year warranty, plus were expected to operate for a home computer user for about 5 years. Thus, we would expect the fan to also operate for five years without failure. [Read more…]

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I must not MTBF

I must not MTBF. MTBF is the mind-killer. MTBF is the little-death that brings total obliteration. I will face my MTBF. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the MTBF has gone there will be nothing. Only Reliability will remain.

Bene Gesserit Litany Against Fear. (with apologies)

by Fred Schenkelberg 25 Comments

How to Calculate Warranty Failures

Let’s say we have a product that most often fails for one major component. Let’s say a fan (it could be anything, and while I don’t have anything against fans, it’s easy to picture).

Ok, this fan has a data sheet with the classic reliability claim of 50,000 hours MTBF. For those that know about my disdain for MTBF (www.nomtbf.com) rest assured I’m not going to get into it here. The basic approach for estimating the number of failure during any [Read more…]

by Pete Stuart Leave a Comment

Shaping Organizational Behavior

When conducting a Human Reliability Assessment (HRA) we use the terminology: errors of commission or errors of omission. It behoves every professional to question why we focus upon one metric in preference to all others, in an objective and constructive manner in order to discern whether we are exposing our organization to errors of professional omission or commission. Obviously the other conclusion is that we are doing the right thing and this is also an empowering piece of knowledge. [Read more…]