Your Reliability Engineering Professional Development Site
All articles listed in reverse chronological order.
In the article Process Capability I – Overview and Indices, the main process performance indices were defined. In the article Process Capability Analysis II – Estimating Percent Defective, ways to calculate the percent defective were introduced.
In this article, the mathematical connection between the Cp index and percent defectives is made.
A key characteristic of Design of Experiments is the resolution. This is a concept that is often misunderstood, or not understood at all. We have attempted to provide a quick discussion so a user can determine if they are at risk. [Read more…]
In most organizations being a reliability engineer is a lonely position. I like to think we’re so effective that one or just a small team is all any an organization needs.
As with any engineering position, we have specialized training and skills. We view the world and problems just a little differently than others. Then we use statistics, which tends to future isolate us from our peers.
For over 50 years there have been professional societies focused on supporting the professional education of reliability engineers. For nearly as long there have been trade journals and newsletters. Longer for technical journals and other scientific and engineering organizations and journals. [Read more…]
Those who know me well know I am a voracious reader. From newspapers and magazines to business related books and novels it’s a rare site to find me without my Kindle or some type of printed reading material. Lately I have noticed a number of articles on the reasons why your best employees are leaving your business and I have to say I saw this problem trend coming more than a decade ago. [Read more…]
Many explosions in the processing, manufacturing and bulk materials handling industries involve flammable gases or vapours and explosive dusts or fibres. Such chemicals are known as hazardous materials. This article provides a basic overview of the design requirements for hazardous areas.
Guest Post by Malcolm Peart (first posted on CERM ® RISK INSIGHTS – reposted here with permission)
Most of us are aware of the old saw “the operation was successful, but the patient died!” which has been around since 1829 and used to describe medical, as well as military and business failures. There are many reasons for failure but is ‘over-management’ one of them? Can too much ‘project management’ be applied to the point that the aim of the project, i.e. the product, is compromised? [Read more…]
One of several reasons for emphasizing product requirements includes enabling modeling and simulations of designs, as well as ensuring adequate verification and validation testing.
Recall the fundamental framing of a requirement as:
Note the framing (within the requirement) of a mathematical and/or experimental relationship where “Y” is the output as a function of “(x)” as the input….Y = f(x) or as a function of multiple inputs Y = f (x1, x2, x3…xn). Let’s expand on this for a moment:
This is part of a short series on the common life data distributions.
The Pareto distribution is a univariate continuous distribution useful when modeling rare events as the survival function slowly decreases as compared to other life distributions. This short article focuses on 7 formulas of the Pareto Continuous Distribution also known as the Pareto distribution of the first kind (there are three kinds, apparently). [Read more…]
I was asked “Do you know about Singularity design?” I hadn’t heard the term in that context before.
It’s the concept of not approaching design from multiple disciplines. The design process is done with an approach and knowledge base of all needed disciplines at once and in conjunction. The electrical system isn’t designed by an electrical team and the mechanical by a mechanical team. The “Design Team” 
designs both simultaneously. Team members knowledge might be rooted in one discipline but there is clearly no boundary to their knowledge of other disciplines. This would be a mechanical engineer who has designed a PC board before.
In my prior article, Process Capability I – Overview and Indices, the process capability concept was defined for prototype samples and serial production. The data is assumed to be normally distributed and Pp, Ppk, Cp, and Cpk indices were defined. Its application to one-sided and two-sided tolerances was discussed. This article provides methods to estimate the percent defective.
The engineering tolerance for a critical characteristic is 10±0.2. So the lower specification limit (LSL) is 9.8 and the upper specification limit (USL) is 10.2. A sample of 30 parts provided measurements of the critical characteristic. The sample mean ($-\bar{x}-$) was 9.951 and the sample standard deviation (s) was 0.1825.
Assessing the occurrence ranking is one of the more challenging aspects of FMEAs. This article presents problems that relate to occurrence risk assessment, based on a fictitious case study, and highlights a common mistake.
Having visited hundreds of manufacturing plants in the last 17 years, someone recently asked me if there were any traits the most reliable plants all had in common. I have listed below the top 6 signs of a reliable plant. [Read more…]
To be innovative, you need to resolve competing requirements. How does someone do that through testing? Over 20 years ago, we created a process that has worked for us and countless others when applying Design of Experiments. These tidbits may help you accomplish more in your new product development.
This article covers the operation of steam traps and how they work. Steam is a greatly used medium. Its use ranges from heating process and domestic fluids through to driving turbines by the expansion of the vapour. Yet the steam trap at the bottom of a drop leg is easily forgotten. [Read more…]
Guest Post by Geary Sikich (first posted on CERM ® RISK INSIGHTS – reposted here with permission)
What is risk? Think about it before you leap to answer. Do we really know and understand risk? Some facts to consider:
Risk management requires that you constantly monitor recognized risks and continue to scan for new risks. This process cannot be accomplished with a ‘one and done’ mindset. Risk needs to be looked at in three dimensions and perhaps even four dimensions to begin to understand the “touchpoints” and aggregation of risk, potential to cascade, conflate and/or come to a confluence. [Read more…]