Your Reliability Engineering Professional Development Site
Short essays and thoughts (musings) on reliability and maintenance engineering topics.
Let me know your reaction and thought, plus any questions.
ISSN 2329-0080
Key Performance Indicators (KPIs) are measurable values related to essential business objectives.
A KPI provides a means to monitor the performance of a specific function.
In larger organizations, with sales & marketing, research & development, operations, supply chain and other teams working to bring products to market, each department has a specific role. [Read more…]
Next week is RAMS – the Reliability and Maintainability Symposium. A multitrack 3.5-day conference with classes, tutorials, paper sessions, a small trade show, plus many of you – peers, colleagues, and friends in the reliability world.
The conference is hosted by 9 professional societies and organized by a group of about 50 or so volunteers from those societies (I was an active member of the RAMS management committee for many years). [Read more…]
None, actually.
Or, one really good reliability engineering professional.
Or, an entire staff of highly talented reliability engineers.
The number of reliability engineers on staff really doesn’t matter. The outcome of your product and system reliability is not contingent on headcount or office space or list of degrees. [Read more…]
One way to capture and disseminate reliability engineering related information and advice is through internal documents. This of course only works if they are both useful and used.
Focus on gathering and providing essential and meaningful information that will improve the reliability of your product. Another element that makes these design guidelines valuable is if they save time. Engineers love to save time. [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…]
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…]
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…]
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…]
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.
Reliability or life testing involves estimating the expected durability over time of an item.
This may be an entire system, a product, or an individual component. We may also focus on an element of a component, such has a material property.
At the end of the testing, we want to say something meaningful about the expected performance over time. [Read more…]
Highly Accelerated Life Testing (HALT) is a technique to expose weaknesses or faults with a product.
HALT uses individual or combined stresses in a step stress approach to quickly apply sufficient stress to reveal defects.
HALT is not a specific chamber or fixed set of test conditions. It is an exploratory process to reveal weaknesses in a design.
The product development process naturally includes a check step, to determine if the expected functions of the product work as expected.
Some teams then add a measured amount of stress (temperature, vibration, dust, load, etc.) to the product to explore functionality at elevated stress levels. [Read more…]
In short, you probably do, better reliability performance the better the brand image.
When I’m making a purchase I prefer to buy items that I either have personal experience work well over time (reliable) or have many comments and reviews noting the durability.
As a reliability engineer, I am often asked what kind of car I drive (a Toyota Highlander, if must know). Reliability does matter -not only to me- it matters for many making a buying decision.
When a product’s actual reliability performance exceeds the customers expected reliability performance, the customer may consider the product reliable. This experience builds and when supported by other experiences from the same brand, increases brand equity. High brand equity permits a price premium, increased brand loyalty, and increased positive word of mouth support. [Read more…]
Why do so many avoid failure?
In product development of plant asset management, we are surrounded by people that steadfastly do not want to know about or talk about failures.
Failure does happen. Let’s not ignore this simple fact. [Read more…]
Everything varies.
Your vendors provide components with a range of values. Your production process varies, too.
Creating, monitoring, and maintaining process stability enhances your product reliability performance.
When I started my professional life as a manufacturing engineer, a senior engineer told me we take a product design and can only make it worse.
He said if we could make every unit exactly according to the nominal values of the drawing, every unit would work well. [Read more…]
The trite answer is just as many samples as you need and not one more.
A better answer is enough samples to make the right decision. The realistic answer is you will not enough samples.
“How many samples?” is an oft-asked question when planning for quality or reliability testing. [Read more…]