Notes

Sample Size and Duration and MTBF

14586653159_c098ab23c9_m_dSample Size and Duration and MTBF

If you have been a reliability engineer for a week or more, or worked with a reliability engineer for a day or more, someone asked about testing planning. The conversation may have started with “how many samples and how long will the test take?”

You have heard the sample size question.

Continue reading “Sample Size and Duration and MTBF”

Learn to Notice MTBF Everyday

14586638599_24177bfb25_m_dLearn to Notice MTBF Everyday

Did you notice the speed limit signs in your neighborhood today?

If like me, you went about your commute or regular travels relatively blind. You watched for the neighbor’s dog that jumped into the road last week, yet didn’t register seeing the speed limit sign.

It’s a cognitive burden to notice the mundane or known. Continue reading “Learn to Notice MTBF Everyday”

The 3 Best Reasons to Use MTBF

14586620299_60a4c792ef_m_dThe 3 Best Reasons to Use MTBF

This may seem an odd article for the NoMTBF site. Stay with me for a moment longer.

Over the years of speaking out on the perils of MTBF, there has been some push back. A few defend using MTBF. Here are three of the most common (maybe not exactly the best, per se) reasons to use MTBF. Continue reading “The 3 Best Reasons to Use MTBF”

Illuminating MTBF’s Lack of Information

14586612669_cc57c310e0_m_dIlluminating MTBF’s Lack of Information

Here’s a simple illustration of how MTBF oversimplifies data concealing essential information.

By convention, we tend to use MTBF for repairable data. That is fine.

You may also be aware of my dislike for the use of MTBF, for many different reasons. If you find yourself suggesting your organization, customer, industry or whomever to stop using MTBF, you may want to use this simple example to illustrate the ‘value’ of MTBF. Continue reading “Illuminating MTBF’s Lack of Information”

MTBF Search Result Sadness

Equipment that didn't advertise with MTBFA Quick MTBF Search Reveals Distressing Results

I was preparing to write this article and wondered how many search hits would appear for MTBF? So, opened Google and did an MTBF search. It is a common if misunderstood, acronym.

Beyond the 5,200,000 Google search results, it was the first page results that got me thinking. Keep in mind that Google often serves up a combination of what it thinks you are seeking and which sites have been useful for others.

Let’s break down what you find when you do an MTBF search. Continue reading “MTBF Search Result Sadness”

4 Questions to Ask When Confronted with MTBF

14805045513_43a0509d1b_z4 Questions to Ask When Confronted with MTBF

MTBF comes up a bit too often. When it does I have found rolling my eyes and arguing against using MTBF is not very effective.

So, what should a knowing reliability professional do instead?

Let’s explore four questions that you can ask that may help others find the value in no longer talking about MTBF. Continue reading “4 Questions to Ask When Confronted with MTBF”

Replace After MTTF Time To Avoid Failures – Right?

MTTF and maintenanceReplace After MTTF Time To Avoid Failures – Right?

Received a short question last week. The person writing seems to already know the answer, yet asked:

If we replace an item after a duration equal to the MTTF value, we would avoid failures, right?

Well, no, most likely not, was my response. What is your response? How would you answer this question? Continue reading “Replace After MTTF Time To Avoid Failures – Right?”

The Relationship Between Reliability Goals and Confidence

14803836443_5a40e52835_oReliability Goal and Confidence

We establish reliability goals and measure reliability performance.

They are not the same thing. Goals and measures, while related, are not the same nor serve the same purpose. Continue reading “The Relationship Between Reliability Goals and Confidence”

Another Way to Spot Someone Confusing MTBF

Vintage machine image, without confusing MTBFYet Another Way to Misunderstand MTBF

In a Q&A forum, the response to a question concerning failure rate and repair times for a redundant system demonstrated yet another person confusing MTBF with something it is not.

The responder to the question mentioned the reference to repair time implied the need for MTBF as a metric. Then went on to describe MTBF as the duration of repair time, which should not change given a redundant system over a non-redundant system. Continue reading “Another Way to Spot Someone Confusing MTBF”

Bought a House Due to Pokemon Go

Reliability and Pokemon GoWalking, Playing and Bought a House

Seriously, while out walking, listening to a podcast, and playing Pokemon Go, found an open house to view. A week later our offer was accepted and next week we close.

I  would not have been out walking that Sunday afternoon if not out playing Pokemon Go.

Glad there are no dangerous cliffs nearby. Continue reading “Bought a House Due to Pokemon Go”

3 Ways to Improve your Reliability Program

The reliability performance of equipment is a reflection of your reliability programA Few Simple Ideas to Improve Your Reliability Program

Spending too much on reliability and not getting the results you expect? Just getting started and not sure where to focus your reliability  program? Or, just looking for ways to improve your program?

There is not one way to build an effective reliability program. The variations in industries, expectations, technology, and the many constraints, shape each program. Here are three suggestions you can apply to any program at any time. These are not quick fix solutions, nor will you see immediate results, yet each will significantly improve your reliability program and help you achieve the results you and your customers expect. Continue reading “3 Ways to Improve your Reliability Program”

What is Reliability?

14784844872_7b7908dd94_zGuest Post by Martin Shaw

In today’s complex product environment becoming more and more electronic, do the designers and manufacturers really understand what IS Reliability ??

It is NOT simply following standards to test in RD to focus only on Design Robustness as there is too much risk in prediction confidence, it only deals with the ‘intrinsic’ failure period and rarely has sufficient Test Strength to stimulate failures. Continue reading “What is Reliability?”

Failure Happens – It Is What Happens Next That Matters

When a failure happens with our equipment our measured response mattersFailure Happens – It Is What Happens Next That Matters

One of the benefits of reliability engineering is failure happens.

Nothing made, manufactured, or assembled will not fail at some point. It is our desire to have items last long enough that keeps us working. Since failures happen, our work includes dealing with the failure.

Not My Fault

Years ago while preparing samples for life testing at my bench, I heard an ‘eep’ or a startled sound from a fellow engineer. It was quickly followed by an electrical pop noise and a plum of smoke.

Something on the circuit board she was exploring had failed. With a pop and smoke. She didn’t move.

At this point, my initial amused response turned to concern for her safety. She was fine, just startled as the failure was unexpected. She quickly claimed it wasn’t her fault.

It was her design, she selected and assembled the parts, and she was testing the circuit. Yet, it wasn’t her fault. She did not expect a failure to occur (a blown capacitor – which we later discovered was exposed to far too much voltage), thus it was not her fault.

We hear similar responses from suppliers of components. It must have been something in your design or environment that caused the failure, as the failure described shouldn’t happen. It’s not expected.

Well, guess what, it did happen. Now let’s sort out what happened and not immediate assign blame for who’s fault it is.

The ‘not my fault’ response so a failure is not helpful. Failures are sometimes the result of a simple error and quickly remedied. Other are complex and difficult to unravel. The quicker we focus on solving the mystery of the cause of the failure, the quicker we can move on to making improvements.

Warranty

With possibly too many ‘not my fault’ responses, laws now enjoin the manufacture of products to stand behind their product. If a failure occurs, sometimes within specific conditions, the customer may ask for a remedy from the supplier.

If failures did not happen there would be no such thing as a warranty.

A warranty is actually a legal obligation, yet has turned into a marketing tool. A long warranty implies the product is reliable and by offering a long warranty the manufacturer is stating they are shifting the risk of failure to themselves.

A repair or replacement is generally not adequate recompense for a failure, yet it provides some restitution. In most cases, it only provides peace of mind, if the item doesn’t fail.

The warranty business has become an industry in of itself. Selling, servicing, and honoring warranties is something that others can deal with outside your organization. The downside is the lack of feedback about failure details so you can affect improvements. A manufacturer shouldn’t hide behind their warranty policy, nor ignore the warranty claim details. It is one-way a customer can voice their expectations concerning product reliability. You should listen.

Repair services

My favorite outsourced repair service story involved a misguided payment structure.

If you pay a repairman based on the value of the components replaced, they will likely always replace the most expensive components. If the repair is accomplished by resetting a loose connector, nothing is replaced, and the repairman is not compensated for the diagnostic work and effective repair. If he instead immediately replaced the main circuit board, and in the process reseating most of the connectors, the repair is fast, effective, and he is handsomely rewarded.

See the problem?

When a failure occurs, it may be natural to offer a repair service as the remedy. It should be quick (not a two-week wait as with my local cable company to restoring a fallen line), and efficient for all parties involved. For the owner of the equipment, we want the functionality restored as quickly as possible and cost effectively as possible. For the manufacture of the equipment, we want cost effectiveness, plus the knowledge concerning the failure.

Does your repair service provide for the needs of both parties as well as the repair technician?

Fail safe

Sometimes when a failure occurs nothing happens. We might not even notice the failure occurs. Other times the product simply goes ‘cold’ or a function is lost. Nothing adverse, no pop or smoke, occurs.

We call this failing safe. It’s more complicated than my simple explanation, yet it is the desired repose to a failure. The product itself should not create more damage, cause harm, place someone in peril. It should fail safely and preferably quietly.

If the ignition falls from the ignition switch, which may be considered a failure to retain the key within the switch, the driver should not lose control of the vehicle. This is in part a safety feature, yet is also a common expectation that the failure of a system should not create other problems.

Failure containment is related.

How does your product fail? Safely?

Maintenance

For some failures, such as the degradation of lubricants, we perform maintenance. When the brake pads or tire tread wears to marginally safe level we replace the brake pad or tire. If we can anticipate the failure pattern we perform preventive maintenance.

Creating a maintainable piece of equipment is one response to failures. It allows creating complex equipment with failure prone elements. Through maintenance, we are able to restore the system to operation or avoid unexpected downtime. If failures didn’t occur, we wouldn’t need maintenance.

We have some control over the nature of the maintenance activities. For some types of failures, we can only execute corrective maintenance. For others, we can use preventative methods. The idea is to anticipate and avoid the widest range of failures through effective maintenance practices, that remains cost effective.

Adding maintenance practices in response to system failures is not the duty of the owner of the equipment. It is a design function to anticipate the system failures that may occur and devise the appropriate maintenance plan to thwart unwanted failures from occurring. The two parties actually have to work together to make this work well.

Expectations

When I buy a product, I know that some proportion of products like the one I just purchased will failure prematurely. I just do not want or desire mine to fail. My expectation is the one I select at the store is a good one. It won’t let me down, stranded, or injured. That is my expectation.

When a failure does occur and I value the functionality the product provides I will want to restore the unit via repair or replacement, sometimes via a service contract or warranty or repair center. To a large degree, my expectation is after a failure all will go well.

As the manufacture of products, when a failure occurs, your expectations may include learning from the failure to make improvements. Or it should.

We know we cannot anticipant nor avoid every failure that may occur. The expectation on both sides is to make robust and dependable products that provide value for all involved. When that approach fails, we fail.

Failure Happens

In response to a failure, it’s how the product, customer, and manufacture responds that matters. A simple failure can turn into a disaster for all involved. Or the failure can provide insights leading to breakthrough innovations and new opportunities.

It’s how we respond that matters.

How do you respond to failures?