Your Reliability Engineering Professional Development Site
Just asking a customer how reliable they want your product often provokes an honest answer. The customer, and you most likely, do not want any failures.
Failures are troublesome or in some cases dangerous.
You and your customers realize that not every unit produced will operate over a long and useful life. There is some chance that something will fail. The definition of ‘some’ is often vague. [Read more…]
The reliability engineer may have many roles within an organization.
You may be specialized and focused only on the analysis of field data. Or you may be a member of the organization’s strategic leadership team.
You might support one or more product development teams, or work with a team of reliability professionals supporting just one subsystem. [Read more…]
Monte Carlo relies on data that describes the variation of elements within the system. It also connects the elements such that they result is an estimate of performance.
For reliability modeling, this is easiest to imagine for a series system.
For a system with two elements in series, a very simple reliability block diagram multiples the expected reliability for each block to determine the system reliability value. Yet, it is possible to have both elements at the low end of the range of possible reliability values, or the high end or a mix.
That is the value of the Monte Carlo approach. [Read more…]
Ethics relate to the moral correctness of a person’s behavior given the groups moral principles.
Society, in general, has a set of standard expectations to guide our behavior. This includes fundamentals such as not harming others or behaving in a deceitful manner.
Religious, professional and informal ‘codes’ document the set or principles which guide our behavior in line with moral correctness. [Read more…]
Fault Tree Analysis (FTA) is a technique to explore the many potential or actual causes of product or system failure.
Best applied when there are many possible ways something may fail. For example, when my car doesn’t start, it could be a dead battery, faulty started, loose wire, no fuel, and on and on. [Read more…]
You have signed up to sit for the CRE exam.
You have the education and experience. Then, you look at the CRE body of knowledge—the breadth of statistics, the range of tools, the plethora of concepts.
You need to review the material. Where do you start?
Each organization creates their own version of a product life cycle.
Often there are phase gate reviews that signal a transition from one phase to the next. In general, each set of phases follows a common progression from idea to retirement.
There are many references that include a description of the life cycle phases, so let’s explore two of them. [Read more…]
Customers experience product failures.
Understanding these failures that occur in the hands of customers is an essential undertaking. We need this information to identify increasing failure rates, component batch or assembly errors, or design mistakes. [Read more…]
The planning of environmental or reliability testing becomes a question of sample size at some point.
It’s probably the most common question I hear as a reliability engineer – how many samples do we need. [Read more…]
Estimating the set of stress and stress curves is an interesting exercise that may have a greater purpose: safety.
The connection is clear when considering the potential consequences of failure.
For example, the loss of braking power when landing an aircraft may result in the aircraft rolling off the end of the runway. This could be into a river or road and may have a rather poor outcome not only for the aircraft. [Read more…]
Becoming an ASQ CRE is one milestone in your career. It involved gathering experience and studying the broad reliability engineering body of knowledge.
It also involved an ongoing application of what you know and learn. I’ve found being a reliability engineer involves learning about materials, designs, systems, people, and tools & techniques. Mastery takes time and a good library. [Read more…]
Ideally, in every design of every component, the stress–strength relationship looks like this figure. The stress is well below the strength.
This implies there is very little chance of failure due to the element being overstressed.
Also, ideally, we fully characterize all stresses and all strengths for each element of a product. This is generally difficult to accomplish and it is rarely done to that extent.
Every once in a while I see a comment that by following the HALT methodology you will “over design” a product.
Many question at what point or operational limit do you quit increasing the stress-strength margins. Those who hold this view of HALT do not understand the essence of what was Gregg Hobbs’ principles and paradigm shift. [Read more…]
Embarking on a product development project contains many aspirations, including that the product should work as expected.
The device functions and does so over time. Enough time for the customer to deem the device reliable.
That is one way to approach setting a reliability goal for a project. Estimate what will delight the customer. Set a target for how long without failure your new design function.
The goal provides a focus for the team. [Read more…]
You may already know my position on MTBF.
If not, do not use MTBF at all, ever, in any form. So what should we use instead?
I suggest using reliability, the probability of success over a specific duration.
Let’s discuss what will work for you.
