All articles listed in reverse chronological order.

Metal Fatigue Failure Mechanism Accelerated Life Testing

Metal is a wonderful, strong, material. Yet under certain types of stresses metal can fail One in particular is fatigue due to cyclic motion.

Metals in a solid state have an atomic level lattice structure. This provides the strength and flexibility. It is the flexibility part that causes trouble. We don’t get the benefit of flexibility for free. As the metal bends it ‘adjusts’ the lattice to accommodate the motion. In doing so, it changes the metal properties becoming a bit more brittle, for example.

In most cases a very small motion causes imperceptible changes and loss of functionality. In some cases, like bending a wire coat hanger with the intent to break it, just a few cycles of dramatic bending is enough to break the wire.

In metal applications that experience cyclic motion and the risk of metal fatigue failure may occur during the expected duration of product use, we may need to characterize the time to failure behavior. An accelerated life test for a metal fatigue failure mechanism is not difficult, yet does take some planning to get meaningful results. [Read more…]

by Doug Plucknette Leave a Comment

Hiring a Consultant? Choose Great Over Good!

A Simple Method To Ensure You Get the Best!

Several weeks ago a customer I worked with back in 2005 called me to ask some questions about a specific Root Cause Analysis process they were using as well as the facilitator they were working with. While I was familiar with the RCA process they were using I admitted to them I had never attended the formal training program offered by the company and while I did know the facilitator I had never seen him facilitate a formal RCA.

My customer then asks me a more difficult question; “Would you recommend we use this methodology as our select supplier for Root Cause Analysis training?” [Read more…]

by Adam Bahret 1 Comment

Prognostics

Engineers have been applying Prognostics to mechanical components for many years.

For example:

Motors, increase in current or noise
Mechanical pumps, progressive increase in vibration
Thermal systems, time to achieve a set temperature
Fluid systems, change in pressure

However, most industries building systems with mechanical components choose not to use prognostics because of the cost of the instrumentation within the product. Products that have on board “smarts” can choose to include diagnostics with less effort or expense. With advances in technology, the cost of the instrumentation is dropping. This not only means that adding the hardware to support advanced metrology is more feasible but that many of these components/systems may have already been added for other functionality and controls improvements in the product. It doesn’t take much brainstorming to find creative ways to use these existing sensory systems. [Read more…]

by nomtbf Leave a Comment

High MTBF with Low Reliability

Can You Have a High MTBF and Low Reliability?

As regular readers know, MTBF by itself is misleading. When representing actual data it can be deceptive as well. Just because you have a high MTBF value doesn’t mean it is reliable.

In a previous article, 10 Reasons to Avoid MTBF, I mentioned that it is possible to have a relatively high MTBF value when the actual reliability is low. Ashley sent me the following note:

Hi Fred, i love reading your articles they are very informative. I have a question about something you said in a comment which i am hoping you will be able to clarify for me. You said products with higher MTBF can actually be less reliable than products with a lower MTBF

I have tried to find information on how this is possible online, and tried to do the maths myself to make this happen but i have to admit i am struggling.

No worries, Ashley, let’s work out an example to illustrate what I meant. [Read more…]

by James Kovacevic 1 Comment

What is Criticality Analysis? How Does it Work?

Understanding the risks allow effective mitigation plans to be put in place

Where is your biggest risk to the site? If you can’t answer that, than your maintenance program is most likely not adequate. As previously discussed, an effective maintenance program must align with business and its needs. A criticality analysis allows the site to understand where there are risks that must be managed. [Read more…]

by James Reyes-Picknell Leave a Comment

Capital Asset Management: Setup — part 2

The rest of us are missing the boat!

Check out part 1, too.

RCM has two potential uses – to set you up for success or to regain success from the jaws of failure.
Regardless of when you use it though, RCM alone isn’t enough to get all the benefits. Applying it after the systems are in service, to recover shortfalls in performance, and then failing to follow up on RCM’s results only delivers part of the benefit. That’s where the aircraft and nuclear industries and the military have it right – they take those extra needed steps. The rest of us don’t! [Read more…]

by Greg Hutchins Leave a Comment

Space Tourism

Guest Post by Paul Kostek (first posted on CERM ® RISK INSIGHTS – reposted here with permission)

After writing several articles about topics related to medical devices and big data, thought I’d explore a new area, risk and space tourism.

Though I will include one interesting note about medical devices, on the October 20^th episode of 60 Minutes former VP Dick Cheney admitted that he had the external programming capability for his defibrillator turned off to prevent it from being hacked. So, even as people question the possibility of this occurring we have a real world example of the steps taken to prevent this from happening. Think risk mitigation. [Read more…]

by Mike Sondalini Leave a Comment

Preventative Maintenance Stops Breakdowns

Preventative maintenance stops breakdowns. Preventative Maintenance requires people to regularly walk around looking, feeling, listening, smelling (sometimes even tasting) and thinking about their equipment’s operating condition. The three foundations of classical Preventative Maintenance are regular lubrication checks, drive train monitoring and equipment mounting inspections.

Keywords: work order, inspection, watchkeeping, CMMS, computerised maintenance management system. [Read more…]

by Fred Schenkelberg 20 Comments

Temperature & Humidity Accelerated Life Testing

Peck’s Relationship

High temperature & humidity is a common test condition. For specific failure mechanisms, there are models available (or you can create a model) to determine the translation from test to use conditions.

These acceleration models generally only apply to one specific failure mechanisms and do not apply to a system level estimate of life. If the failure mechanism is the dominant failure mechanism for the product, then an ALT exploring just that mechanisms would provide a life estimate.

Peck’s relationship is an acceleration model for the effect of humidity on the metallization elements of integrated circuits within plastic enclosures (typically an epoxy over molding). [Read more…]

by Kevin Stewart Leave a Comment

Characteristic 2 of an RCA Program

A Plan to Provide Program Resources

Who

Sometimes we get so used to managing without things that it becomes the way things are done. An astronaut giving a presentation at a conference I attended referred to this as “normalization of deviance.” In other words, we get so used to the way things are, that either right or wrong, they become the norm! Unfortunately, the obvious is many times ignored – because it is obvious. If you intend to have a sustainable Root Cause Analysis program, then there are things that must be done. People must be trained, reports must be written, analyses must be performed, and progress must be tracked and reported. Until a program becomes self-sustainable, it must continue to be driven. [Read more…]

by Dennis Craggs 1 Comment

Analysis of Continuous Variables

Telematics data analysis can be used to improve our understanding of how people use their vehicles. It is an objective source to validate product requirements. In cars and trucks, sensor signals are read by electronic modules share the data on a CAN bus. Some signals contain data for continuous variables. Some examples of continuous variables are vehicle speed, engine speed, engine torque, ambient temperatures, in-vehicle temperatures, pressures, voltages, and the battery state of charge. Another name for the continuous variables is parametric data. This CAN data is a rich source of information

[Read more…]

by Fred Schenkelberg Leave a Comment

The Case of Drones

Guest post by Dr. Amir Segal & Yizhak Bot of BQR

Introduction

Reliability engineers are equipped with an arsenal of techniques (FTA, RBD, Markov, FMEA / FMECA, SIL) for reliability, availability, safety and maintainability analysis. However, it is not always clear when to use each technique.
In order to design a safe and reliable product, reliability engineering techniques should be integrated with the system design process. This fact is well known, and today many system engineering conferences include discussions regarding reliability and safety [1,2]. [Read more…]

by Doug Plucknette Leave a Comment

10 Things You Can Do To Get More Enjoyment Out of Business Travel

Several weeks ago, I wrote an article titled the 10 Worst Things About Business Travel. Anyone who has traveled extensively for business will tell you that life on the road can become both mundane and exhausting. Run into me on my third week of travel in an airport, and I’m likely to be a touch grumpy. I’m ready to go home, spend time with my family and sleep in my bed.

After reading the article, a friend of mine asked me why I continue to travel for a living, “You could get a job at 50 different companies in Rochester, if the travel is so bad, why not stop?” [Read more…]

by Adam Bahret Leave a Comment

Relating to Reliability Goals

Reliability goals are often communicated in Mean Time Between Failure (MTBF) 40,000 hrs, Failure rate 0.00035, or percentage still functioning over time 99.98%. If you are not familiar with actually calculating these numbers they really don’t mean a lot. Are any of those above numbers good? bad? something we will even measure before release?

Are any of those above numbers good? bad? something we will even measure before release? [Read more…]

by Adam Bahret 2 Comments

Is This HASS Any Good?

HASS doesn’t break stuff like HALT. HASS is like a good physical examination from a doctor: It gives you the thumbs up or thumbs down on health based on a quick and thorough examination. But a good thorough examination is possible because of research, education, and practice.
[Read more…]