Is it possible to foresee all reliability issues before a product launch?
No.
I don’t think so. Can we minimize surprises from field failures?
Yes.
The number of potential failures is often unknown.
Perfect Reliability
Reliability Success Stories
Reliability engineering has value. It can improve product reliability, increase uptime, and drive customer satisfaction, for example.
Here are a couple of stories based on real situations that resulted in significant value for the organization.
Levene’s Test
Here’s an overview of the non-parametric test to evaluate if a set of samples have the same variance. If the variances are equal they have homogeneity of variances.
Some statistical tests assume equal variances across samples, such as analysis of variance and many types of hypothesis tests. It is also assumed for statistical process control purposes to determine stability (often done with range (r chart) or standard deviation (s charts). [Read more…]
Successful Career in Reliability Engineering
Successful Career in Reliability Engineering
How does one become a reliability engineer?
How does one create a career based on reliability engineering?
In my experience, I have seen several paths and have observed a number of key traits that make for a successful career.
This discussion examines the traits of successful reliability professionals from different industries.
The combination of those profiles and my experience with coaching dozens as they built their careers has provided a unique insight into the key traits that separate a rewarding from an unfulfilling career in reliability engineering.
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Contingency Coefficient
A contingency table, as in the chi-squared test of independence, reveals if two sets of data or groups are independent or not. It does not reveal the strength of the dependence. The contingency coefficient is a non-parametric measure of the association for cross-classification data. [Read more…]
Reliability Target Establishment
“The language we use matters.” Wayne Nelson
How we talk about reliability does matter. It sets expectations and influences decisions. We talk about reliability as it is important to our customers and our business. The successful operation of the equipment in a plant permits the production of products. The successful operation of the product satisfies the needs and expectations of our customers.
Chi-Square Test of Independence
The chi-square ( $- \chi^2 -$) test provides a means to determine independence between two or more variables. In this case, it works for count data.
Contingency table or row and column (r x c) analysis are other common names for this analysis. It is useful when comparing results from different treatments or processes. [Read more…]
Reliability Testing
Years ago a client asked for help in reducing the amount of reliability testing they did for each project. They had a sense that some of the testing wasn’t useful. What they want to know was how to select the appropriate testing and be sure they wouldn’t miss anything important.
Two Approaches to Reliability
There are two basic approaches when addressing product reliability: Reactive or Proactive. Neither is right or wrong.
The reactive approach has the limitation of responding to failures that occur during prototyping, production and customer use.
The proactive approach focuses on preventing product design, assembly, and use issues before they have the opportunity to create a product failure.
Kaplan-Meier Reliability Estimator
Here’s an overview of a distribution-free approach commonly called the Kaplan-Meier (K-M) Product Limit Reliability Estimator.
There are no assumptions about underlying distributions. And, K-M works with datasets with or without censored data. We do need to know when failures or losses (items removed from the evaluation or test other than as a failure. Censored items). [Read more…]
CRE Prep course
Just opened registration for a CRE preparation course. http://fmsrel.com/1hW57Yt
Starting in August and running through September. All online.
Can you Delegate Reliability?
A common expectation consumers have concerning products is that the product works. The product provides value by performing one or more functions. Also, implicit with this expectation is the product will function over some duration. A reliable product meets or exceeds this common expectation.
Every product has a finite duration of successful operation before failure occurs.
The Value of a CRE Certification
Recently I participated in an ASQ CRE focus group with a few of our peers. The ASQ facilitator prompted each of use to answer a few questions. Then she asked each of us to contribute to a “Start, Stop, Change” exercise focused on the CRE exam.
It appears ASQ is starting another round of reviews and possible updates to the CRE Body of Knowledge and exam process. That is good. [Read more…]
Kruskal-Wallis Test
This is a non-parametric test to compare ranked data from three or more groups or treatments. The basic idea is to compare the mean value of the rank values and test if the samples could are from the same distribution or if at least one is not.
The null hypothesis is the data from each group would receive about the same mean rank score. We are comparing rank values, not the actual values. [Read more…]
The Music of Data
We are good at collecting data, now use it
In Katmandu, I visited a small pottery factory. There was a young man sitting at a potting wheel making candle stands. He didn’t measure anything and I doubt anyone did.
Based on experience and just looking at a finished item, he could tell if it was acceptable or not. That was good enough.
