What is Validation?

Significant savings in product development costs can be realized with robust validation processes, starting with requirements validation. Validation confirms the product meets customer needs for the products intended use, and answers the question “are we designing the right product?” The “right product” therefore starts with the “right” product requirements. Even a product designed with detailed requirements, but incorrect specification limits, can be considered the “wrong product” (since the product would be rejected by the customer.) [Read more…]

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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. [Read more…]

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Why success with HALT begins long before doing HALT

Implementing a new reliability development paradigm in a company which is using traditional, standards-based testing can be a perilous journey.

It is especially true with introducing HALT (Highly Accelerated Life Test) in which strength against stress, and not quantifying electronics lifetimes is the new metric. Because of this significant change in test orientation, a critical factor for success begins with educating the company’s top [Read more…]

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For Maximum Test Value, Take it to the Limit!

When we go to an automobile race such as the Indianapolis 500, watching those cars circle the track can get fairly boring. What is secretly unspoken is that everyone observing the race is watching for a race car to find and sometimes exceed a limit, finding a discontinuity. The limit could be how fast he enters a curve before the acceleration forces exceed the tires coefficient of friction, or how close to the racetrack wall, he can be before he contacts it and spins out of control. Using the race analogy, [Read more…]

by Kirk Gray 4 Comments

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.
[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 1 Comment

Basic Approaches to Life Testing

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…]

by Fred Schenkelberg 2 Comments

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 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…]

by Fred Schenkelberg 5 Comments

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 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.

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Environment Element of Reliability Goal

This element of a reliability requirement answers the questions of where and under what conditions the product should operate.

It includes storage, transportation, and installation conditions too. One way to think of the environment is to consider the weather around the device. Temperature, humidity, preoccupation, etc.

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Use Profile and the Reliability Definition

How a customer uses a product matters. It matters in the amount and type of stress your product receives. It determines the life span. Someone that uses the product often isn’t necessarily going to have a short life span, it might be the lack of use that most damages a product.

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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.

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Question use of reliability testing standards

Each of us have seen product life or component reliability claims on product literature or data sheets. We may even have received such claims stated as goals and been asked to support the claim with some form of an experiment. Standards bodies from ANSI, BSI, ISO, IEC, and others from around the world provide standard methods for testing products. This includes product life testing in some cases. [Read more…]

by Fred Schenkelberg Leave a Comment