Articles

My introduction to reliability engineering was my boss asking me to sort out how long a new product will last in use.

The expectation was it would last for 20 years or more buried in Italian mountain concrete bridges.

My first thought was about living in the Dolomites for 20 years monitoring the performance of the product.

That was quickly dashed as my boss explained he wanted an answer in about 6 months.

Now this was a problem. How do you cheat time to learn about the expected lifetime of a something? Thus started my career in reliability engineering.

Life testing for reliability engineering helps us answer the question how long till failure occurs. Specifically, we find the chance of failure over some duration. [Read more…]

Perfect Reliability? The product lasts too long?

In the poem by Oliver Wendall Holmes, The One Hoss Shay, a deacon is confounded by the various parts of his carriage the fail.

And, he decides to do something about it.

But the Deacon swore (as Deacons do,
With an “I dew vum,” or an “I tell yeou,”)
He would build one shay to beat the taown
‘n’ the keounty ‘n’ all the kentry raoun’;
It should be so built that it couldn’ break daown:
“Fer,” said the Deacon, “t’s mighty plain
Thut the weakes’ place mus’ stan’ the strain;
‘n’ the way t’ fix it, uz I maintain, Is only jest T’ make that place uz strong uz the rest.”

Translating from old English, it basically means he wanted to craft a carriage using the best materials and techniques. Later, he built a very sound carriage where every part is just as strong as all the other parts. [Read more…]

Is it possible for an individual to ‘do’ DFR? Is design for reliability something, like a specific technique, that is DFR?

What is DFR and how would you recognize it if it was occurring? Like meditation, nearly anyone can strike a pose that appears similar to someone in deep meditation, yet can you tell by observation if they really are mediating? Probably not. The same is true for an organization or person that declares they are doing DFR. Maybe they are or maybe not.

[Read more…]

Environmental testing is the evaluation of a product or system in one or more stress conditions. Environmental as in that which surrounds and affects a product. Consider temperature. Is the product going to experience outdoor temperatures as found in Fargo, North Dakota or Belmopan, Belize?

The weather is one way to describe external stresses, yet it is so much more. Environmental testing may include fungus, insect, and animal exposure. The document MIL-STD-810G lists and describes testing methods for a wide range of environmental conditions. [Read more…]

Stop testing when the testing provides no value.

If no one is going to review the results or use the information to make a decision, those are good signs that the testing provides no value. Of course, this may be difficult to recognize.

Some time ago while working with a product development team, one of the tasks assigned was to create an ongoing reliability test plan. This was just prior to the final milestone before starting production. During development, we learned quite a bit about the product design, supply chain, and manufacturing process. Each of which included a few salient risks to reliable performance.

[Read more…]