Exploring the differences between HALT and ALT, or Highly Accelerated Life Test and Accelerated Life Test. Plus when to use which when.
[Read more…]HALT or ALT
on Product Reliability
A listing in reverse chronological order of articles by:
- Kirk Grey — Accelerated Reliability series
- Les Warrington — Achieving the Benefits of Reliability series
- Adam Bahret — Apex Ridge series
- Michael Pfeifer — Metals Engineering and Product Reliability series
- Fred Schenkelberg — Musings on Reliability and Maintenance series
- Arthur Hart — Reliability Engineering Insights series
- Chris Jackson — Reliability in Emerging Technology series
Reliability vs. Durability
It seems a big misconception in different industries between those two terms “Reliability” and “Durability”. So, first thing first, I apply google research to find out what is definitions:
Reliability is defined as the probability that a product, system, or service will perform its intended function adequately for a specified period of time or will operate in a defined environment without failure. (Source American Society for Quality (ASQ))
Durability is the ability of a physical product to remain functional, without requiring excessive maintenance or repair, when faced with the challenges of normal operation over its design lifetime. (Source Wikipedia)
[Read more…]How to not Suck at Probability and Statistics
A simple way of looking at our brain is by dividing it into the conscious, subconscious and unconscious minds. The conscious mind is all about what we are actively thinking about in the here and now. We might be navigating as we drive through the countryside. We might decide to take an exit from the main road because our conscious mind has worked out that the map we are looking at is showing us that’s what we need to do to get to where we want to go.
ALT or Durability Test?
A brief discussion on the difference and similarities of accelerated life testing (ALT) and durability testing. For one difference, ALT used high stress conditions to shorten the time to failure. Whereas, durability testing typically uses whole products and normal use condition.
[Read more…]Normal Distribution in Reliability Analysis
Normal distribution is most common in real life scenarios be it modeling any reliability performance parameter at a specific time. Central Limit Theorem (CLT) shows why normal distribution occurs so often.
[Read more…]Always Looking for Someone to ‘Sign Off on That? … Your Organization is Probably Struggling
When I was a bright eyed, motivated (younger) officer in the Australian Army, one my many tasks when deployed overseas was to raise paperwork to formally request ‘battlefield material’ to be sent back home from whatever country we were in. ‘Battlefield material’ was items that included a range of mementos, keepsakes, and things you would typically see in a museum to add to the historical collections of my battalions and regiments back home.
Why Weibull Distribution is Most Common Used in Engineering?
Ernst Hjalmar Waloddi Weibull (18 June 1887 – 12 October 1979) was a Swedish engineer, scientist, and mathematician. (source Wikipedia)
Preventive Maintenance and the Toxic ‘Need to do Something’
For thousands of years, doctors treated virtually every skin ailment by ‘letting’ or draining the blood of the patient. Leeches are really good at doing this as they quite literally drink up the allegedly ‘poisoned’ blood that is being removed. Of course, by the late 1800s, science had advanced to the point where it was realized that this was nonsense, and so leeches fell out of favour in the world of medicine.
But that same scientific revolution saw the development of drugs like heroin and cocaine to cure everything from schizophrenia through to children’s cough. With doctors prescribing these drugs left right and centre, and worldwide epidemic of drug-addiction misery was spawned.
[Read more…]Understanding Data Distribution in Reliability Analysis
Having a knowledge of how the data is distributed is critical to model failure times and life in reliability analysis. Every distribution is unique and suitable for different types of reliability data.
[Read more…]DOE – What are You?
The history of Design of Experiments (D.O.E) can be traced back to the work of various individuals, including Genichi Taguchi, a Japanese engineer and statistician. Taguchi made significant contributions to the field, particularly in the area of robust design, which aimed to improve the quality of products and processes. His work was influenced by the need for quality improvement in post-World War II Japan. Taguchi’s methodology, known as the Taguchi methods, was based on the concept of “robust parameter design,” which aimed to make processes and products insensitive to environmental factors or other variables that were difficult to control.
[Read more…]And Now to the Biggest IT Outage … Ever!
It is no small irony that a software application that is designed to protect IT systems from malicious actors was behind the biggest IT outage in the history of computers. A company called Crowdstrike provides a ‘Falcon Sensor’ product that is intended to scan computers that use Microsoft operating systems for vulnerabilities. And this product is deployed so deeply into its host operating systems that it has access to the ‘kernel,’ which is the program that runs the basic code that links applications to the computer hardware (like memory, central processing unit and other devices). Unfortunately a Falcon Sensor update that Crowdstrike sent to its customers had a bug that was not picked up by its own validation programs (because it too had a bug). And unfortunately, it accesses a ‘forbidden’ part of the memory that causes the infamous BSOD or ‘blue screen of death.’ So airlines, hospitals, banks, hotels and lots of other companies simply couldn’t operate.
What is Acceptable Test Duration?
And again there is no one answer for such simple question. Strongly depends on what type of test you need to conduct.
It is also very important to understand at which stage, design of the product. Usually at very early stages of the design there is many unexpected failures, when design is mature enough – failures become predictable, and there is one last period, called – wear out/aging stage.
[Read more…]Benchmarking (by definition) Makes you Average. At Best.
How heavy should you be? Perhaps this is a sensitive question. The average weight of a human is about 65.2 kg or 143.7 lbs. So if your weight is above this figure, are you ‘too heavy’? Conversely, if you are below this figure, are you ‘too light’? Being over and underweight can bring a whole raft of health consequences.
Hopefully you would agree with me in saying that the ‘average’ human weight is not a good benchmark to use if you want to get healthier. Or at least it is not the only benchmark you should think about.
But unfortunately … many manufacturers use approaches that are embarrassingly close to this ridiculous approach to continual improvement.
8D in RCA
The 8D (Eight Disciplines) method is a problem-solving methodology designed to find the root cause of a problem, devise a short-term fix, and implement a long-term solution to prevent recurring problems. It was first introduced in Ford’s 1987 Team-Oriented Problem Solving manual and has since become a widely used problem-solving method, also known as Global 8D. The 8D process consists of eight disciplines, each focusing on specific aspects of problem-solving
[Read more…]No … 89 percent of Failures are NOT Random
I am constantly confronted by students, reliability engineers and other people banging fists on tables and saying …
… 89 percent of failures are random …
Firstly, 100 percent of failures are random. It’s just that there are lots of textbooks and experts telling us that a ‘random’ failure is one that happens irrespective of age. That is, a failure with a constant ‘failure rate’ where the item in question doesn’t appear to age or wear out.
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