Blog - Accendo Reliability

No Evidence of Correlation: Field failures and Traditional Reliability Engineering

Historically Reliability Engineering of Electronics has been dominated by the belief that 1) The life or percentage of complex hardware failures that occurs over time can be estimated, predicted, or modeled and 2) Reliability of electronic systems can be calculated or estimated through statistical and probabilistic methods to improve hardware reliability. The amazing thing about this is that during the many decades that reliabilityengineers have been taught this and believe that this is true, there is little if any empirical field data from the vast majority of verified failures that shows any correlation with calculated predictions of failure rates.
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by Fred Schenkelberg 6 Comments

Success Testing Formula Derivation

The planning of environmental or reliability testing becomes a question of sample size at some point.

It’s probably the most common question I hear as a reliability engineer – how many samples do we need. [Read more…]

by Fred Schenkelberg Leave a Comment

How Safe is Safe Enough for Your System?

Estimating the set of stress and stress curves is an interesting exercise that may have a greater purpose: safety.

The connection is clear when considering the potential consequences of failure.

For example, the loss of braking power when landing an aircraft may result in the aircraft rolling off the end of the runway. This could be into a river or road and may have a rather poor outcome not only for the aircraft. [Read more…]

by Fred Schenkelberg Leave a Comment

The 2015 Recommended References Survey

Becoming an ASQ CRE is one milestone in your career. It involved gathering experience and studying the broad reliability engineering body of knowledge.

It also involved an ongoing application of what you know and learn. I’ve found being a reliability engineer involves learning about materials, designs, systems, people, and tools & techniques. Mastery takes time and a good library. [Read more…]

by Fred Schenkelberg 3 Comments

The Stress-Strength Concept in Practice

Ideally, in every design of every component, the stress–strength relationship looks like this figure. The stress is well below the strength.

This implies there is very little chance of failure due to the element being overstressed.

Also, ideally, we fully characterize all stresses and all strengths for each element of a product. This is generally difficult to accomplish and it is rarely done to that extent.

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by Fred Schenkelberg Leave a Comment

Does HALT Lead to Product Over-Design?

Every once in a while I see a comment that by following the HALT methodology you will “over design” a product.

Many question at what point or operational limit do you quit increasing the stress-strength margins. Those who hold this view of HALT do not understand the essence of what was Gregg Hobbs’ principles and paradigm shift. [Read more…]

by Fred Schenkelberg 1 Comment

3 Elements of Reliability Goal Setting

Embarking on a product development project contains many aspirations, including that the product should work as expected.

The device functions and does so over time. Enough time for the customer to deem the device reliable.

That is one way to approach setting a reliability goal for a project. Estimate what will delight the customer. Set a target for how long without failure your new design function.

The goal provides a focus for the team. [Read more…]

by Fred Schenkelberg Leave a Comment

Life Testing Starting Point

Reliability or life testing involves estimating the expected durability over time of an item.

This may be an entire system, a product, or an individual component. We may also focus on an element of a component, such has a material property.

At the end of the testing, we want to say something meaningful about the expected performance over time. [Read more…]

by Tim Rodgers 2 Comments

Improving Quality in China

Many years ago people would complain about “cheap Japanese” products, but today few people would associate Japanese brands with poor quality.

The turn-around is widely attributed to Deming, and Taguchi, and Juran, and other evangelists who taught not only the tools and processes but also the long-term benefits that can be realized when a company adopts good practices and a culture of quality.

Today I hear people complaining about poor quality in Chinese-made parts and products, and there have been several widely-publicized incidents (see Aston-Martin and counterfeit parts).

Many customers have decided to move their production and seek part suppliers in other locations, including “re-shoring” to North America, in part because they’ve concluded that any cost savings due to cheaper labor are outweighed by the costs of poor quality.

It’s hard to say whether this will have a negative impact on the worldwide consumer perception of Chinese brands such as Lenovo, Haier, and others.

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by Fred Schenkelberg Leave a Comment

Warranty Policy Establishment

A common question concerns the warranty period.

How long should we, the manufacture guarantee that our product will work as expected? Do we include limitations or not? How do we decide? [Read more…]

by Fred Schenkelberg 2 Comments

A Brief Introduction to HALT

Highly Accelerated Life Testing (HALT) is a technique to expose weaknesses or faults with a product.

HALT uses individual or combined stresses in a step stress approach to quickly apply sufficient stress to reveal defects.

HALT is not a specific chamber or fixed set of test conditions. It is an exploratory process to reveal weaknesses in a design.

The product development process naturally includes a check step, to determine if the expected functions of the product work as expected.

Some teams then add a measured amount of stress (temperature, vibration, dust, load, etc.) to the product to explore functionality at elevated stress levels. [Read more…]

by Fred Schenkelberg Leave a Comment

The Exciting World of Warranty Terms

Here’s a short list of terms related to warranty management. Often is the words we use that matter and understanding the language of warranties is one step in mastering warranty management.

Warranty

A promise made to the buyer of an item that the manufacturer (seller) will repair or replace the item if necessary within a specific time period. [Read more…]

by Tim Rodgers 3 Comments

Why Should a Supplier Work Harder For You?

A recent LinkedIn discussion addressed the question of the best strategy for dealing with poor supplier performance.

A lot of the respondents seemed to advocate a punitive approach, either threatening the loss of future business if performance doesn’t improve, or combing through the terms & conditions of the contract for enforcement language.

I’ve always thought that there’s a lot of similarity between managing suppliers and managing subordinates, and I wonder if some of these same people threaten their teams with punitive actions when individual performance doesn’t meet expectations. [Read more…]

by Fred Schenkelberg 1 Comment

What is the Link between Reliability and Brand?

In short, you probably do, better reliability performance the better the brand image.

When I’m making a purchase I prefer to buy items that I either have personal experience work well over time (reliable) or have many comments and reviews noting the durability.

As a reliability engineer, I am often asked what kind of car I drive (a Toyota Highlander, if must know). Reliability does matter -not only to me- it matters for many making a buying decision.

When a product’s actual reliability performance exceeds the customers expected reliability performance, the customer may consider the product reliable. This experience builds and when supported by other experiences from the same brand, increases brand equity. High brand equity permits a price premium, increased brand loyalty, and increased positive word of mouth support. [Read more…]

by Fred Schenkelberg 1 Comment

Warranty Evolution and Laws

When making a transaction there is an element of trust.

The buyer is trusting you are providing a product that lives up to the claims provided. Neither party wishes to be duped. Yet, we do enter into transactions. We buy stuff.

A few hundred years ago and prior most purchases were from someone you knew, and most likely knew well. It was in the craftsman’s best interest to maintain honest dealing and create quality products. If not, they would enjoy less business. [Read more…]