Your Reliability Engineering Professional Development Site
Find all articles across all article series listed in reverse chronological order.
Guest Post by Ed Perkins (first posted on CERM ® RISK INSIGHTS – reposted here with permission)
While we look at risk-based decisions and making decisions under uncertainty, these approaches all have one basic assumption – that the participants in these processes are doing so consciously, with eyes open and with an appreciation of the risks and consequences involved. [Read more…]
There are a few different reasons we explore differences in scale.
Keep in mind that the scale of a dataset is basically the spread of the data. For most datasets, we’re examining the variance.
Hypothesis tests comparing means vary depending on the assumption of equal variances. Thus testing that assumption requires methods to adequately test the homogeneity of variances. The F-test should come to mind as it is a common approach.
Some datasets do not lend themselves to using the F-test, which is applicable using real numbers. Some datasets gather information that is ordinal or interval data, thus we need another approach to test for differences in scale. [Read more…]
Welcome to part seven of my 10-part series of blogs called “Uptime Insights”, where we explore a journey of excellence in maintenance.
To stay on top, managers must implement strategies that keep operations performing at high levels. In these articles, I will show you how to achieve excellence in maintenance – a critical business process in any capital intensive industry.
Computerized systems are important and now seemingly indispensable tools for business. Just remember the last power failure you experienced and you’ll understand.
There isn’t much that isn’t computerized these days. Technology and its business applications continue to grow and proliferate. The world of maintenance is no exception.
Most maintenance work is not computerized, but it is complex and managing it requires sophisticated tools. Using those tools effectively will improve the efficiency with which you deliver maintenance services.
Use them poorly and you only add cost. [Read more…]
What is the one thing that all operations have? If you guessed a breakdown hero or fire fighter, you are correct.
You know the person who swoops in like Superman and repairs a machine quickly. These breakdown heroes are the people who reduce the time to repair, but do they contribute to or reduce the reactivity of the site? [Read more…]
If you look around you day to day you can see a lot of examples of reliability testing.
When you are at the hardware store and looking at new power tools, notice which have broken switches, triggers, handles. Many of us often just think it’s a defective one. But it’s not. It’s the weakest model of the bunch.
If all the models were put on display at similar times they have all been going through life cycle testing. Every person that walks by picks it up and pulls the trigger, flips the switches bangs it around a bit.
It’s getting its life cycle testing done right in front of you. The one with the broken features is the model with the shortest life. [Read more…]
Polyethylene is one of the most commonly used engineering plastics.
Its chemical resistance properties and ease of fabrication make it popular in the chemical industries. Its molecular structure provides the key to its versatility.
Keywords: HDPE, long chain macromolecule, thermoplastic, plastic welding. [Read more…]
Guest Post by Malcolm Peart (first posted on CERM ® RISK INSIGHTS – reposted here with permission)
It has been suggested that Stone Age man had a higher IQ than today’s modern homo sapiens.
“That cannot be,” says the modern man, but if one thinks about such an assault on our modern-day ego and self-confessed superiority, the alleged ‘primitive’ man was able to survive in extreme conditions, traveled the planet and set the foundations for today’s societies. [Read more…]
The Hartley test is an extension of the F distribution-based hypothesis test checking if two samples have different variances.
The F test works with two samples allowing us to compare two population variances based on the two samples. This test does not work for three or more populations. We could conduct multiple pairwise comparisons, yet the probability of an erroneous result is significant.
Bartlett’s Test and Levene’s Test are non-parametric checks for homogeneity of variances. Bartlett’s Test pretty much expects the underlying data to be normally distributed.
Levene’s Test is a better choice when you’re not sure the data is normal. Both are conservative and time-consuming to calculate.
We need another way to check for equal variances. [Read more…]
Sigma, σ, is the Greek character we use to represent standard deviation. 6 σ represents the spread of data about the mean. For data with a normal distribution, 6 σ includes 99.7% of the data.
The 6 σ design approach incorporates knowledge of the variation that will occur within the design such that the design has is unlikely to fail.
According to Mikel J. Harry, the foundation of excellence in product quality rests on achieving six sigma product quality. [1] [Read more…]
Welcome to part six of my 10-part series of blogs called “Uptime Insights”, where we explore a journey of excellence in maintenance.
To stay on top, managers must implement strategies that keep operations performing at high levels. In these articles, I will show you how to achieve excellence in maintenance – a critical business process in any capital intensive industry.
The work management process is essential to keeping costs under control in maintenance but how will you know if you are doing well if you don’t measure what you are doing and the results you get?
Performance management is another essential for maintenance management. Costs are important, results are important and so are the processes you use to turn costs into results.
Performance management is central to managing those processes so you get the most output for the least input – the greatest cost effectiveness. [Read more…]
As Engineers, Craft and Maintenance people, we have a tendency to be excited by the technological advancements that become available.
This is not a bad thing provided we do not let them become the flavor of the month or take our attention away from what we are here to do. Enable Reliability and Maintenance.
Often we find much information on the advanced technical topics such as Reliability Engineering, Life Cycle Costing, or various CBM technologies. When properly deployed, these techniques allow us to further our success in Reliability and Maintenance.
But what about the foundations that make these interesting techniques successful? [Read more…]
Guest Post by David Patrishkoff (first posted on CERM ® RISK INSIGHTS – reposted here with permission)
We are living in a time of great disruption and uncertainty.
Every organization is facing great risks. Some of these risks are visible and many others are hidden.
So, it’s crucial that every company develops and implements tools to identify, mitigate and transform risks into dramatic improvements and even disruptive innovations. [Read more…]
Valves can be used to both isolate and regulate liquid and gas flow.
Valve used for isolation duties must provide secure, tight shut-off. Consideration must be given to the nature of the process chemical, the quality of sealing and the impact of outside environmental occurrences.
Keywords: bubble tight, design pressure, leakage rate, fire rated, differential pressure. [Read more…]
The data analysis course professor tended to focus on the practical application of statistics.
Avoiding statistical theory was fine with me. Learning statistics for me was on how to solve problems, optimize designs, and understanding data.
Then one lecture started with the question, “Why do we sum squares regression analysis, ANOVA calculations, and with other statistical methods?” He paused waiting for one us to answer.
We didn’t. I feared the upcoming lecture would include arcane derivations and burdensome theoretical annotations. It didn’t. [Read more…]
In a single meeting, you may need to structure a reliability model, create estimates, outline test plans, and discuss a field failure. The breadth of tools and knowledge to be effective is staggering.
No two problems, questions, situations, or industries are the same. Thus, the solutions you provide must differ as well. If you enjoy a complete set of reliability engineering tools at your disposal, you are well situated to address any question.