Here at Agilian, we often use test to failure to evaluate how durable and reliable components and products are likely to be during the new product development process. For electro-mechanical products, this reliability testing methodology involves pushing the limits of the things being tested until they fail in order to find defects, vulnerabilities, and more which can then be fixed long before the product goes into production. We’ll go over what’s involved and the benefits to you right here…
You can listen to an interesting discussion about test to failure in this episode of our podcast:
Why do we test to failure?
If we consider electronic products, users often expect them not to fail and will be highly inconvenienced if they do. No matter if it’s a car, cellphone, laptop, airplane, pacemaker, server, fire alarm, cooker, etc, if these devices stop working it will, at best, leave users annoyed, and at worst, could be dangerous and result in property damage, injuries, or even deaths. We’ve already covered product returns and how costly they are in terms of money and reputational damage, but you also need to contend with product safety, too.
Test to failure during the NPI process is beneficial because it helps you to determine if a product can stand up to its regular operating conditions and beyond. As I wrote in QualityInspection.org:
There are usually 2 goals for this kind of testing:
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To assess and confirm the product’s limits – i.e. if a product needs to handle 100 volts, how do you know if it is able to handle it if you do not test it above and beyond this voltage?
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To give yourself a margin of failure – this is your product’s reliability, and in this case, if the product can handle up to 120 volts even if it’s going to be used with 100 volts, then you are giving yourself a 20% margin of failure.
By subjecting the component or product to conditions above its expected usual operating environment it helps you to build reliability into the product by having a margin of failure/reliability to fall back on. The closer you are to its limits when you go into production, the higher your risk of failure if there is any change in its operating environment.
5 benefits of this testing
- Finds and fixes the product’s weaknesses until the margin of reliability is adequate.
- Enhances product safety by removing (or at least vastly reducing) the risks of, for example, a battery exploding.
- Improves quality as defects will be reduced.
- Costs are reduced because product returns and warranty claims are minimized.
- Innovation is spurred, as product engineers are pushed to find new solutions to reliability problems which make their way into the design.
Methodologies you can use when testing to failure
By now you’ve seen what test to failure is and its benefits, but if you implement this testing, which testing methodologies might be used? Here are a few to consider:
Accelerated Life Testing (ALT)
This test is designed to make the product fail faster by subjecting it to elevated stress conditions, such as high or low temperatures, humidity, etc, that mimic the effects of those stress conditions over a longer time period. It is possible to add more than one stress condition to the mix as other variables, as in real life, too. If failures occur, these can be investigated and fixed, and you will know at what level the stress conditions were at when they occurred so you have an idea of your reliability margin.
Environmental testing
- The product is tested in realistic environmental conditions like temperature, humidity, and vibration similar to road, rail, and air conditions (during transport). Any failure modes are noted and can be investigated.
High-stress testing
Products and components are subjected to excessive stress conditions of voltage, temperature, etc, to assess how well they can handle a high-stress environment. Although these conditions might be outside their normal usage environment, they allow you to test the limits of their reliability before they fail.
Cyclic loading
Over the lifetime of a product, it and its components will be subjected to changing conditions, such as hot temperatures in summer and cold in winter. Cyclic loading mimics these changing conditions by repeatedly testing products under alternating stress conditions to assess how they deal with that kind of stress. This helps you assess how reliable they will be when in the field.
Continuous monitoring
The product or component needs to be monitored during operation to ensure that it is staying within expected performance levels. Engineers should be alerted if wear or changes are occurring that suggest that it is going to fail.
Once a problem has been fixed and the improved product is being sold continuous monitoring is also important because you need to check any returns for the former issue. If it does seem to be occurring again, maybe the fix hasn’t been effective. Engineers can also check when a fix was made by referring to the lessons learnt database which it should have been entered into.
Industries that embrace test to failure
As we’ve mentioned, test to failure pushes products and components to their limits so you get an accurate idea about their reliability and how safe they will be for users. How far they can handle above their expected operating environment is your margin of reliability. As you can imagine, the higher the margin of reliability, the more reliable a product will be even in extreme circumstances, but it may also be more expensive, too.
Many industries use test to failure, such as:
Automotive
Cars have numerous critical components that can’t be allowed to fail easily, such as safety systems, brakes, airbags, etc. It’s a matter of user safety that the vehicle is extremely reliable and so components need to be durable enough not to fail when they’re needed most.
Consumer electronics
Aside from the inconvenience of a device that stops working, manufacturers also need to consider the safety implications of when a lithium-ion battery explodes, for example. Devices that consumers rely on every day can’t afford to fail as this would be very damaging for the manufacturer’s reputation.
Medical devices
It goes without saying that the highest level of reliability and safety is needed here. Imagine a pacemaker that stops working. That’s a danger to life and simply unacceptable, therefore, a test to failure will help you develop a product that is as close to 100% reliable as possible.
Aerospace
Airplanes do need to operate in extreme conditions, such as turbulence, storms, changes in temperature and pressure, etc. You can be sure that their components have been tested to failure to ensure an extremely high reliability margin.
Industrial equipment
When a modern automobile production line goes down it might cost up to one hundred thousand dollars a minute until it is back up and running. While an extreme example, this shows that industrial equipment needs to be very reliable and do what is required from it no matter when.
Get help to test your components or products
Our in-house testing lab offers a full range of reliability and safety tests, such as testing to failure as described here. If you have any questions about product reliability and testing in general, do let us know and we’ll be glad to offer guidance and assistance where needed.
