Category Archives: Engineering

Life Data Analysis with only 2 Failures

Life Data Analysis with only 2 Failures

Here’s a common problem. You have been tasked to peer into the future to predict when the next failure will occur.

Predictions are tough.

One way to approach this problem is to do a little analysis of the history of failures of the commonest or system. The problem looms larger when you have only two observed failures from the population of systems in questions.

While you can fit a straight line to two failures and account for all the systems that operated without failure, it is not very satisfactory. It is at best a crude estimate.

Let’s not consider calculating MTBF. That would not provide useful information as regular reader already know. So what can you do given just two failures to create a meaningful estimate of future failures? Let’s explore a couple of options. Continue reading Life Data Analysis with only 2 Failures

Exposing a Reliability Conflict of Interest

Is Your Organization Compromising Reliability Performance Due to a Reliability Conflict of Interest?

Kirk Gray wrote the article titled Exposing a Reliability Conflict of Interest on Accendo Reliability. He talked about a recent article discussion the maintenance costs for the F-35 fighter jet program and how the companies designing the system make a significant profit selling spare parts or maintenance services.

If you count on the profit from the system you design failing, you have an inherent conflict of interest concerning creating a reliable system.  If you create a reliable product you lose money. Continue reading Exposing a Reliability Conflict of Interest

Should One Profit From Failures?

Should One Profit From Failures?

“Do not improve reliability as it cuts into our repair activity profits.” Is this a way to run a reliability program?

I’ve seen this in action and that company is no longer in business. In another situation the field service department withheld vital information to improve products lest his department (and self-importance) dwindle.

Is this a bad business model, or is it just my thinking it not so smart? Continue reading Should One Profit From Failures?

A Life Data Analysis Challenge

old machinery couplingHere is a Challenge: Life Data Analysis

Some years ago a few colleagues compared notes on results of a Weibull analysis. Interesting we all started with the same data and got different results.

After a recent article on the many ways to accomplish data analysis, Larry mentioned that all one needs is shipments and returns to perform field data analysis.

This got me thinking: What are our common methods and sets of results when we perform life data analysis? Continue reading A Life Data Analysis Challenge

The Many Ways of Data Analysis

Given Some Data, Do Data Analysis

Let’s say we have a set of numbers, {2.3, 4.2, 7.1, 7.6, 8.2, 8.4, 8.7, 8.9, 9.0, 9.1} and that is all we have at the moment.

How many ways could you analyze this set of numbers? We could plot it a few different ways, from a dot plot, stem-and-leaf plot, histogram, probability density plot, and probably a few other ways as well. We could calculate a few statistics about the dataset, such as mean, median, standard deviation, skewness, kurtosis, and so on. Continue reading The Many Ways of Data Analysis

The Challenges in Reliability Engineering

What are the Other Challenges in Reliability

Creating a product or system that lasts as long as expected, or longer, is a challenge.

It’s a common challenge that reliability engineering and entire engineering team face on a regular basis. It’s also not our only challenge.

We face and solve a myriad of technical, political, and engineering challenges. Some of our challenges are born and carried forward by our own industry. We have tools suitable for a given purpose altered to ‘fit’ another situation (inappropriately and creating misleading results). We have terms that we, and our peers, struggle to understand.

Sometimes, we, as reliability engineers have set up challenges that thwart our best efforts to make progress.

Let’s examine a few of the self made challenges and discuss ways to overcome these obstacles permitting us to tackle the real hurdles in our path. Continue reading The Challenges in Reliability Engineering

Enabling Great Reliability Decisions

Reliability is about making the right decision, each time.

Answering Questions

A common role during a first assignment as a reliability engineering is to answer a question or accomplish a task. It may help someone to make reliability decisions.

We may be asked, as I was, how long will this new product function during use? The director of engineering wanted to know if the new design was reliable enough to meet the customer’s requirements concerning reliability. He didn’t ask it that way, yet he did have a question that needed answering.

Sometimes we run a batch of tests, conduct failure analysis on field returns, or compare the durability to two vendor subsystems. In each case, there is a question to be answered.

A decision to be made by someone else. Continue reading Enabling Great Reliability Decisions

Field Failure: A Quality or Reliability Problem

Field Failure: A Quality or Reliability Problem

When my car fails to start, as a customer I only know that my car didn’t start.

When my phone fails to turn on, or the dishwasher leaks, or the printer jams, I only know I’ve experienced an unwanted outcome.

I really do not care, at the moment, why the coffee maker is not producing my morning cup of coffee. My first thought is ‘now where do I find a cup of coffee?’ As a reliability engineer I’m naturally curious about what caused the failure and can I fix it immediately to get the morning cup brewing.

My thinking does not classify the failure or the source of the failure as a quality or reliability problem. Then why is it that some organizations split reported field failures thus? Continue reading Field Failure: A Quality or Reliability Problem

Reliability is Not Metrics, It’s Decision Making

Reliability is Not Metrics, It’s Decision Making

MTBF, KPIs, yield, return rate, warranty… bah!

We may use one or more of these when establishing product reliability goals. When tracking performance. When making decisions.

Goals, objectives, specifications, and requirements, are stand-ins for the customer’s experience with the product.

We’re not trying to reduce warranty expenses or shouldn’t be solely focused on just that measure. We need to focus on making decisions that allow our product deliver the expected reliability performance to the customer. Continue reading Reliability is Not Metrics, It’s Decision Making

5 Ways Your Reliability Metrics and Fooling You

5 Ways Your Reliability Metrics and Fooling You

We measure results. We measure profit, shipments, and reliability.

The measures or metrics help us determine if we’re meeting out goals if something bad or good is happening, if we need to alter our course.

We rely on metrics to guide our business decisions.

Sometimes, our metrics obscure, confuse or distort the very signals we’re trying to comprehend.

Here are five metric based mistakes I’ve seen in various organizations. Being aware of the limitations or faults with these examples may help you improve the metrics you use on a day to day basis. I don’t always have a better option for your particular situation, yet using a metric that helps you make poor decisions, generally isn’t acceptable.

If you know of a better way to employ similar measures, please add your thoughts to the comments section below. Continue reading 5 Ways Your Reliability Metrics and Fooling You

The Variety of Statistical Tools

The Variety of Statistical Tools to Support Your Decision Making

My wife and I moved to a new home last year. We have yet to organize our tools.

The bedroom and kitchen are now organized. We, for the most part, can find the sweater or pan that we’re seeking.

No so for our tools in the shop. We have an assortment of hand tools for painting, home maintenance, yard work, and woodworking. In our previous home, we had the tools on pegboards, on shelves, in cabinets. We could find the right tool for the job at hand quickly. We’ve avoided the tool aisle at the hardware store recently, as we were sure we had the tool we need in the jumbled mess in our garage already. Still haven’t found it, though.

Have you noticed the number of statistical tools available? It’s like visiting a well-stocked tool store. There are basic tools like trend charting and advanced tools like proportional hazard models. Let’s explore the available tools a little so you can quickly find the right tool for the question or problem you are facing today. Continue reading The Variety of Statistical Tools

The Rule of 3 Significant Digits

Two people have shaped how I guess an answer.

Their comments and guidance have tailored how to form a quick estimate, my ability to articulate a hunch and the effectiveness of those guesses.

You probably guess or make a rough estimate regularly. How good is your gut feel? Do you keep track and score yourself?

Making an estimate should be second nature for you. It’s not something to do in public, too often. The practice can aid you in numerous ways. Continue reading The Rule of 3 Significant Digits

Teaching Reliability is Part of Your Role

Teaching Reliability is Part of Your Role

Nearly everyone I’ve ever met doesn’t like their toaster to fail.

It will, and that is a bummer, as the quick and easy way to warm up the morning toast will be thwarted.

Failures happen. As reliability engineers, we know that failures happen. Helping others to identify potential failures, to avoid failures or to minimize failures is what we do best.

It is out ability to teach others about reliability engineering that allows us to be successful. Continue reading Teaching Reliability is Part of Your Role

Math, Statistics, and Engineering

14586673050_b71972cc74_m_dMath, Statistics, and Engineering

In college, Mechanics was a required class from the civil engineering department. This included differential equation.

Luckily for me, I also enjoyed a required course called analytical mechanics for my physics degree. This included using Lagrange and Hamiltonian equations to derived a wide range of formulas to solve mechanisms problems.

In the civil engineering course, the professor did the derivation as the course lectures, then expected us to use the right formula to solve a problem. He even gave us a ‘cheat sheet’ with an assortment of derived equations. We just had to identify which equation to use for a particular problem and ‘plug-and-chug’ or just work out the math. It was boring. Continue reading Math, Statistics, and Engineering

When Do Failures Count?

14586657179_3359d879f8_m_dWhen Do Failures Count?

One technique to calculate a product’s MTBF is to count the number of failures and divide into the tally of operating time.

You already know, kind reader, that using MTBF has its own perils, yet it is done. We do not have to look very far to see someone estimating or calculating MTBF, as if it was a useful representation of reliability… alas, I digress.

Counting failures would appear to be an easy task. It apparently is not. Continue reading When Do Failures Count?