Anyone that knows me understands that even muttering MTBF in a conversation or even in passing will generally set me off on a anti MTBF tirade. My better friends tend to avoid the topic altogether. And those that are curious about ‘why’ will ask me. In the process I hope to help you think about MTBF and the many issues around its use, and to make or improve friendships. Continue reading Just muttering MTBF
CRE BoK use of MTBF
This past week I’ve heard from a few that have taken the ASQ Certified Reliability Engineer exam. The common comment was on the use of MTBF and the exponential distribution. It seems to emphasized.
That is bad. Continue reading CRE BoK use of MTBF
Value of reliability engineering
Linkedin groups are a continual source of interesting questions. We learn and share with each other to grapple with some of the common and not so common issues we face at work. For example, recently in the Plant Reliabilty & Maintenance Professionals – PRMP Linkedin group the follow in question appeared. Continue reading Value of reliability engineering
MTBF as a Metric
Seeing a book announcement for Duke Okes Performance Metrics: The Levers for Process Improvement made me think. The except titled “Psychological Impact of Metrics” included the notion that metrics drive behavior. That isn’t new, yet Duke went on to provide a way to determine the worthiness of metrics. Continue reading MTBF as a Metric
Reliability Blogs
Reliability Blogs
One of the venues for learning about reliability is the blogosphere. In some cases purely educational, others are more appropriate for the opinion page. Some comment on interesting facets of reliability and maintenance engineering, while others focus on examples of services provided.
Seeing Success Against MTBF
Since posting the article about the internal policy by Grundfos I’ve had a range of discussions concerning your efforts to eradicate MTBF. Very encouraging!
The comment by Mark on the Linkedin NoMTBF group prompted me to write about this information. Mark posted: Continue reading Seeing Success Against MTBF
Assets and MTBF
A colleague and friend, Bill Barto, worked up an example concerning two pieces of equipment. By simply not assuming a constant failure rate the …. well, let Bill tell the story….
Here’s the story in Bill’s own words via Youtube. Continue reading Assets and MTBF
MTBF at RAMS
No MTBF and Reliability and Maintainability Symposium
RAMS is an annual multi track technical conference, rams.org. This year in Orlando and about 400 or so attended. I was rather busy, having two tutorials, and three papers. See my site for a copy of my slides and papers. It was fun, exhilarating, and very enjoyable. Continue reading MTBF at RAMS
Grundfos MTBF Policy
A few months ago at a IEC Dependability standards meeting, I met Thomas Young Olesen of Grundfos and we talked a little about NoMTBF. He said their company has a polity to not use MTBF. YES! So I asked for permission to post some information about the policy.
One interesting part of their internal site was a MTBF Calculator. Continue reading Grundfos MTBF Policy
Lower Confidence
Let’s say we have a population and we are interested in the mean (average) of that population’s life. We select a sample (at random if at all possible) and measure a value, like time to failure, for each selected item in the sample.
We calculate the mean life of the sample by summing the sample values and dividing by the number of items in the sample. Continue reading Lower Confidence
MTBF and preventative maintenance
I find the world of maintenance a very odd place to find MTBF. While it is possible, that a set of equipment or a machine may actually have a constant failure rate it is the exception rather than all that common. Assuming a constant failure rate doesn’t make it so. Continue reading MTBF and preventative maintenance
Designing an ORT
I received a question about setting up an ORT the other day. Below is my response.
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There is not a hard and fast rule for how much life to take out of a product during ORT and still be able to sell the unit.
There are two different reasons to run ORT and each may take a different approach. Continue reading Designing an ORT
Electronics Failure Prediction Methodology does not work
Posted 12-11-2012 by Kirk Gray,
Accelerated Reliability Solutions, L.L.C.
“When the number of factors coming into play in a phenomenological complex is too large, scientific method in most cases fails. One need only think of the weather, in which case the prediction even for a few days ahead is impossible.” ― Albert Einstein
“Prediction is very difficult, especially about the future.” – Niels Bohr* We have always had a quest to reduce future uncertainties and know what is going to happen to us, how long we will live, and what may impact our lives. Horoscopes, Tarot
Continue reading Electronics Failure Prediction Methodology does not work
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. Continue reading MTBF Logic