The bane of our existence is one thing, generating enough data to demonstrate statistical confidence. Every reliability engineer, every project manager, every Director and VP all have the same moment of panic in a new product development program. In synchronicity they put their head in their hand. It’s when the required number of test units and calendar time to demonstrate a required confidence in the reliability goal is calculated. It’s usually about ten times more units than can be acquired and about two times longer than the entire product development program timeline.
Apex Ridge
The Apex Ridge article series covers a diverse set of topics that relate to many of our reader’s work, interests, and experiences. The articles are inspired by industry experiences with the intent of sharing, educating and assisting you with your career challenges and growth. The content is targeted for a diverse audience with backgrounds even extending beyond engineering (Hmm talking to you project and business managers). My hope is that these topics inspire you to have discussions with your colleagues or right in the comments of the series. I look forward to seeing you on-line soon.
Language is The Tragedy of Reliability
I was teaching a class on Reliability 101 a few years ago and it turned out to be one of those great classes where debate and discussion would just pop up all over the place. I frequently start my classes with “If I end up being the only one speaking today I am going to take that as an indication of complete failure in having engaged you in this material.” So I was loving that this group were starting to debate each other on the material we were covering. I wasn’t even in some of the conversations. This rich environment is where I just spurted out one of my more memorable reliability quotes. [Read more…]
Supplier’s Reliability Responsibility
We, as developers, create designs that we call “our own.” Rarely are the materials for our in-house manufacturing process raw steel, rubber, and glass, like Henry Ford had feed into the Ford factory in 1930. Our manufacturing process receives a mix of materials and fully functional sub assemblies from other technology companies. It’s unlikely the PCB electronic components, bearings, motors, gears, drivetrains, sensors, power supplies, harnesses are ours. Why would you design any of these with so many options available made by specialists? This results in us having little input or control in the development and demonstrated reliability of our entire product. [Read more…]
Pioneers and The Settlers
The Pioneers rarely reap the rewards of new discoveries. It’s usually the settlers that really profit from the new expansion. Many companies, especially small ones striving to get into a market, bet on a big technology breakthrough to get their foot in the door. As consumers, we do eventually become aware of “the others” once the market for that technology is in motion. “The others” were quietly watching and diligently developing the improved version based on the experiences of the pioneer’s first take. [Read more…]
The Vasa: An Engineering Disaster
The Vasa is a Swedish ship that was constructed between 1626 and 1628. It is a great story of an engineering disaster, well that’s how it is labeled. It doesn’t take too much investigation to see it is really a leadership disaster.
I saw the Vasa in beautifully restored condition at it’s museum in Stockholm Sweden. It was retrieved from the ocean floor in 1961. Amazingly after almost 300 years it was intact and well preserved in the freezing waters off Sweden. This is it’s story… and warning! [Read more…]
The Importance of Reliability Education
The importance of reliability education in a product development program cannot be understated. A design initiative with mechanical content can be created solely by the mechanical team, same for electrical, and software. These other disciplines will create a better product if they collaborate from the start, but this is not necessary. A successful product can still be created if they intersect later. Reliability doesn’t have this flexibility. Reliability tools don’t have a deliverable like a function or a feature. They are an assist for the function or feature during the process of creation. As an assist discipline, it only works if implemented while the other processes are in motion. Attempting to add it after the design has been completed requires a deconstruction of the previous work if improvements are needed. [Read more…]
Considerations and Pitfalls when Designing ALT
I just returned from the IEEE ASQ Accelerated Stress Test and Reliability Conference, held this year in Austin, Texas. It’s always been a great conference. There is such a good comradery and sharing of knowledge when a large group comes together on such a specific topic. I meet a lot of great people from many different industries, all with great experience to share. [Read more…]
Confidence and “Confidence”
Confidence is used in reliability to give a probabilistic value to the likelihood that a taken measurement will represent a full population. It is determined by measuring a sample size and then using a selected statistical distribution table to translate to a likelihood. Emotional confidence is how one feels about making a decision based on known information at a specific point in time. Similar but different. But it is important to connect them. This is why. [Read more…]
My favorite reliability phrases
I like the occasional good catchphrase. I typically tend to speak in analogies and anecdotes and many of my customers and colleagues have suggested documenting them. So on occasion, I will write them in my notebook. Here are a few. [Read more…]
Estimating Time to Demonstrate Reliability
One of the most difficult challenges of incorporating reliability activities with program planning is estimating the time it will take to demonstrate reliability. Demonstrated product reliability is typically measured as a confidence in a product’s capability to achieve a reliability goal. At product release, the business unit may feel comfortable with their target market and warranty goals with a demonstration of a 90% confidence in the products reliability goal of 99.1%. [Read more…]
Is It Faster to Demonstrate Component Reliability at the System Level?
Here is a common situation that is considered when reliability testing is being planned. Let’s use letters to designate depth in a product component structure. The top level product is level “A” and a component in top sub assembly is “B”. A sub assembly, of a sub assembly, of a sub assembly, is at level “D”. So is it more efficient to test the component at level “E” or at level “B”?
Question: Is it more efficient to test the component at level “E” or at level “B” to demonstrate it’s individual goal? [Read more…]
What is Weibull?
Weibull analysis is a tool that is used for characterizing the behavior of a data set. The value of characterizing a data set is being able to make predictions of failure rate for the same or a similar population. Input to the Weibull analysis is time to fail for all failed units and running time for operating units. The assumptions for the data set are critical to ensuring the right information is included in the analysis. This may include root cause analysis of the failures so they can be characterized as wear-out or use stress related. It would be beneficial to separate these two data sets because their characterization and behavior will be quite different Weibull factors. [Read more…]
The History of Reliability
If you had to section the history of reliability into only two periods I believe the dividing point would be around 1950. The first section, stone age to 1950, the “Robust” era; 1950 to today, the “Margin” era. In the robust, era reliability concerns were addressed by creating a design that was orders of magnitude stronger than required, “over-engineered”. This protected against the variability of fabrication, use, and environment. If it was made sloppily with low tolerances, it still worked; Used for an unintended purpose, still worked; Left out in the snow, dropped in the river, run over by a horse, buried in the sand; still worked. [Read more…]
Mission Profile
Mission profiles are fundamental to any reliability prediction being valid. Without clearly defined environmental and use profiles there will be a long chain of inaccuracy that accumulates into significant errors within a product.
This is what occurs at the following stages, or tools, if the mission profile or environment profile changes after its completion. [Read more…]
The Reliability Engineering Role
What does the reliability engineer do?
Do they design reliable products? Or Do they guide the development of reliable products?
It’s some mix of course. It depends on the process for the organization they operate in. I will point out that neither extreme works. I am often surprised with how many organizations I see that still have the 1950’s model of ” Design it and then give it to the reliability team to make it reliable.” I still don’t believe there is a single person in any engineering role in any engineering organization that believes that works.
That is what one of my old mentors used to call a “window dressing program”. No one believes it actually helps the product but you get to take your customers around your facility and show them all the great testing you are doing (SILENT END OF SENTENCE ” on out of rev parts and in a program phase where results can’t be implemented.”). [Read more…]
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