Musings on reliability and maintenance topics

Short essays and thoughts (musings) on reliability and maintenance engineering topics. Let me know your reaction and thought, plus any questions.
ISSN 2329-0080

What Happens When a Product Lasts Too Long?

July 2, 2015
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What Happens When a 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 […]

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Meditation and Design for Reliability

June 25, 2015
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Design for Reliability is More Than a Set of Tasks 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 […]

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Environmental Testing’s Role with Reliability Engineering

June 18, 2015
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Is Environmental Testing Part of Product Reliability? 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 […]

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When to Stop Testing

June 11, 2015
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When to Stop Testing Stop testing when the testing provides no value. If no one is going to review the results or use the information to make a decisions, 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 […]

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Reliability and Monte Carlo Determined Tolerances

June 4, 2015
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Monte Carlo Method In the Monte Carlo method one uses the idea that not all parts have the same dimensions, yet a normal distribution describing the variation of the part dimensions is not assumed. Although the normal distribution does commonly apply, if the process includes sorting or regular adjustments or if the distribution is either […]

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Reliability and Root Sum Squared Tolerances

May 28, 2015
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Root Sum Squared Method The root sum squared (RSS) method is a statistical tolerance analysis method. In many cases the actual individual part dimensions fall near the center of the tolerance range with very few parts with actual dimensions near the tolerance limits. This of course assumes the part dimensions are tightly grouped and within […]

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Quick Introduction to Worst Case Analysis

May 21, 2015
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Worst-Case Tolerance Analysis Worst-case tolerance analysis is the starting point when creating a tolerance specification. It is a conservative approach as it only considers the maximum or minimum values of part variation—whichever leads to the worst situation. Setting tolerances such that the system will function given the expected variation of manufactured components improves that ability of […]

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Reliability Questions for the Drone Industry

May 9, 2015

Exploring Drone Reliability In a few Twitter conversations I’ve learned about the perceived lack of reliability of commercially available quadcopter or drones. And, being encouraged to write a paper or two on drone reliability. Now that Amazon has a delivery drone patent, and industrial applications continue to announced daily, there is a need for serious […]

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How to Be Deliberately Proactive

May 7, 2015
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How to Be Deliberately Proactive It is not enough to simply state your organization has a proactive stance concerning reliability. It more than running a few tests or thinking about reliability before the product ships or the equipment is installed. It is a way of doing business.

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Reliability Questions to Ask During a Review

April 29, 2015
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Reliability Questions to Ask During a Review Asking the right question is important. During a review meeting (informal or formal) asking a few reliability questions may reveal weaknesses, strengths, or uncertainty. The design team has many priorities and reliability is often difficult to estimate, yet knowing what is and isn’t known provides a clear picture […]

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