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When Do Failures Count?One technique to calculate a product’s MTBF is to count the number of failures and divide into the tally of operating time.
You already know, kind reader, that using MTBF has its own perils, yet it is done. We do not have to look very far to see someone estimating or calculating MTBF, as if it was a useful representation of reliability… alas, I digress.
Counting failures would appear to be an easy task. It apparently is not. [Read more…]
Sample Size and Duration and MTBFIf you have been a reliability engineer for a week or more, or worked with a reliability engineer for a day or more, someone asked about testing planning. The conversation may have started with “how many samples and how long will the test take?”
You have heard the sample size question.
Learn to Notice MTBF EverydayDid you notice the speed limit signs in your neighborhood today?
If like me, you went about your commute or regular travels relatively blind. You watched for the neighbor’s dog that jumped into the road last week, yet didn’t register seeing the speed limit sign.
It’s a cognitive burden to notice the mundane or known. [Read more…]
The 3 Best Reasons to Use MTBFThis 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…]
Illuminating MTBF’s Lack of InformationHere’s a simple illustration of how MTBF oversimplifies data concealing essential information.
By convention, we tend to use MTBF for repairable data. That is fine.
You may also be aware of my dislike for the use of MTBF, for many different reasons. If you find yourself suggesting your organization, customer, industry or whomever to stop using MTBF, you may want to use this simple example to illustrate the ‘value’ of MTBF. [Read more…]
A Quick MTBF Search Reveals Distressing ResultsI 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…]
4 Questions to Ask When Confronted with MTBFMTBF comes up a bit too often. When it does I have found rolling my eyes and arguing against using MTBF is not very effective.
So, what should a knowing reliability professional do instead?
Let’s explore four questions that you can ask that may help others find the value in no longer talking about MTBF. [Read more…]
Replace After MTTF Time To Avoid Failures – Right?Received a short question last week. The person writing seems to already know the answer, yet asked:
If we replace an item after a duration equal to the MTTF value, we would avoid failures, right?
Well, no, most likely not, was my response. What is your response? How would you answer this question? [Read more…]
Reliability Goal and ConfidenceWe establish reliability goals and measure reliability performance.
They are not the same thing. Goals and measures, while related, are not the same nor serve the same purpose. [Read more…]
Yet Another Confused MTBF DefinitionJust when I thought we had experienced every possible MTBF definition confusion, here’s another.
This one is courtesy the thread concerning the impact to reliability when adding redundancy to a system. [Read more…]
Yet Another Way to Misunderstand MTBFIn a Q&A forum, the response to a question concerning failure rate and repair times for a redundant system demonstrated yet another person confusing MTBF with something it is not.
The responder to the question mentioned the reference to repair time implied the need for MTBF as a metric. Then went on to describe MTBF as the duration of repair time, which should not change given a redundant system over a non-redundant system. [Read more…]
Walking, Playing and Bought a HouseSeriously, while out walking, listening to a podcast, and playing Pokemon Go, found an open house to view. A week later our offer was accepted and next week we close.
I would not have been out walking that Sunday afternoon if not out playing Pokemon Go.
Glad there are no dangerous cliffs nearby. [Read more…]
A Few Simple Ideas to Improve Your Reliability ProgramSpending too much on reliability and not getting the results you expect? Just getting started and not sure where to focus your reliability program? Or, just looking for ways to improve your program?
There is not one way to build an effective reliability program. The variations in industries, expectations, technology, and the many constraints, shape each program. Here are three suggestions you can apply to any program at any time. These are not quick fix solutions, nor will you see immediate results, yet each will significantly improve your reliability program and help you achieve the results you and your customers expect. [Read more…]
5 Clues Using MTBF is Not HelpingHave you ever heard the claim that “We use MTBF, as it’s working just fine”?
They may be profitable and successful in the marketplace. Is MTBF serving them well?
Probably not. [Read more…]
Guest Post by Martin ShawIn today’s complex product environment becoming more and more electronic, do the designers and manufacturers really understand what IS Reliability ??
It is NOT simply following standards to test in RD to focus only on Design Robustness as there is too much risk in prediction confidence, it only deals with the ‘intrinsic’ failure period and rarely has sufficient Test Strength to stimulate failures. [Read more…]