Your Reliability Engineering Professional Development Site
A listing in reverse chronological order of articles by:
A reliability block diagram is a graphical and statistical representation of the reliability structure of a system.
Graphical as an RBD is drawn with blocks for each element of a system and connecting lines representing the relationship between elements.
I’ve recently received a couple of notes from individuals looking at starting a career in reliability engineering. One is a student looking at a career path, another a working engineer with an interesting in reliability.
Both asked how to land a position given no reliability engineering experience.
Hum, I don’t know anyone that had reliability engineering experience before they got started working in reliability engineering. Not counting taking apart the family toaster and trying to repair it before Mom got home as a kid.
The easy answer is very often. Each time you want to know how long a product will operate. The accompanying question on how well the estimate will match actual performance makes the real answer more difficult.
We regularly and intuitively do reliability predictions all the time. When starting a car at the beginning of a trip, we estimate the ability of the vehicle to complete the journey. When we purchase a phone, we expect it to operate for at least two years (your expectations may differ).
During the design process, we may have formal or informal useful life expectations. It is not knowing if our decisions related to the design will fulfill the lifetime expectations that leads to the desire to know how well the resulting system will operate. We also may need to estimate warranty or maintenance costs, thus knowing what is likely to fail becomes important.
In general, knowing how long something will operate without failure provides the feedback we need to create a viable system that meets our business and customer reliability expectations.
In short, we do reliability predictions regularly to gauge is we are making good decisions. [Read more…]
Failure modes and effect analysis is a tool to identify potential failures and prioritize based on severity, occurrence, and detection. I like to describe FMEA as an organized brainstorm. You probably have some experience with FMEA.
In some industries, there is a high expectation or mandate to do an FMEA study. In some industries FMEA maybe just another tool to consider using during various stages of the product or asset lifecycle.
In my opinion, FMEA should be a part of your project plan when it is likely to add value.
Value in the sense that the organization will receive an adequate benefit based on the investment to conduct the FMEA study. [Read more…]
HALT (highly accelerated life testing) is a method to reveal product weaknesses. Design prototypes experience the step-stress application of relevant stresses until failures appear.
The intent is to find design or process related weaknesses early in the design process thus providing time to economically address the issue. Using a build-test-fix approach does improve a product’s robustness and reliability.
Being a useful tool, should you conduct HALT on every project? It seems that revealing weaknesses is certainly useful. [Read more…]
“How do you know so much about our program?” was a question the quality manager asked after reading the assessment report. The assessment took one day with eight interviews.
The reliability that results is going to happen whether or not the team designing the product or production line deliberately use reliability engineering tools or not. The elements of a product or system will respond to the environment and either work or fail.
While working at Hewlett-Packard I had the opportunity to conduct reliability program assessment of about 50 product divisions. One hypothesis related the number of reliability tasks the team actively used would correlate to their warranty expenses.
That worked to a point. [Read more…]
The process to create a new product has risk. There are safety, technical, schedule and financial risks
The risk of a product failing more often then deemed acceptable by the customer or the business falls in the realm of reliability engineering to address.
We can provide insight on what is expected to failure and when. Working with the entire team we can influence the design and assembly process to minimize the risk of field failures.
Below is a short list the most common risk reduction tools in our arsenal. [Read more…]
Reliability is an attribute of an item. The item, with its design, assembly, and use, has a finite probability of working over some duration.
We deliberately attempt to create items that meet our and our customer’s expectations concerning that probability and duration. We maintain and operate our equipment with an expectation of successful performance.
We and our customers are let down when a failure occurs. We do not enjoy the benefits of the item’s value. [Read more…]
In a common definition used by engineers reliability is a probability of success. It is the chance of an item operating as expected over some duration in a given environment. In this case, we have probability as part of the definition of reliability.
Reliability in common use definition includes trustworthiness, dependability and similar definitions. It’s more than how many times your friends help you move to a new apartment, it’s a feeling or sense we have concerning our ability to count on our friends for the help.
I do not like procurement organizations.
It is like saying you don’t like lawyers. I don’t know all procurement engineers or managers, so understand my statement is a grand generalization. It’s not the people I don’t like, it’s a common behavior that I’ve witnessed countless times that I do not like.
Procurement organizations tend to look for ways to reduce cost by purchasing less expensive components or materials. This is often done with little regard to the impact on product reliability.
Why is this? And what can we do as reliability professionals to change this behavior? [Read more…]
Have you ever wished your organization would work together to achieve a reliable product? Not just a few individuals and a heavy reliance on the reliability team to focus on highlighting and fixing reliability issues.
Some organizations tend to react to reliability issues. Prototype testing and field returns continue to surprise the team. The worst organization fall into finding someone to blame. Better organizations set to work to understand the problem and quickly resolve the issue. Some have better ‘fire departments’ than others.
Responding quicker is not really the best way to deal with reliability. [Read more…]
Is it possible to foresee all reliability issues before a product launch?
No.
I don’t think so. Can we minimize surprises from field failures?
Yes.
The number of potential failures is often unknown.
Reliability engineering has value. It can improve product reliability, increase uptime, and drive customer satisfaction, for example.
Here are a couple of stories based on real situations that resulted in significant value for the organization.
“The language we use matters.” Wayne Nelson
How we talk about reliability does matter. It sets expectations and influences decisions. We talk about reliability as it is important to our customers and our business. The successful operation of the equipment in a plant permits the production of products. The successful operation of the product satisfies the needs and expectations of our customers.
Years ago a client asked for help in reducing the amount of reliability testing they did for each project. They had a sense that some of the testing wasn’t useful. What they want to know was how to select the appropriate testing and be sure they wouldn’t miss anything important.
