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HALT vs HASS Testing

Technician using a test chamber

How do you develop an accurate warranty? How do car manufacturers know exactly when their models will require maintenance? How do you set customer expectations on a product in general?

The answer, of course, comes on the back of environmental testing. You need to determine the limits of your products, ensure they work as intended, and discover any deficiencies prior to going to market. Otherwise, you risk recalls and all the costs and brand damage that comes with them.

Two of the most popular methods are highly accelerated life testing (HALT, although it’s sometimes shortened to ALT) and highly accelerated stress screening (HASS). Conducting each will give you an understanding of the effectiveness of each component as well as the product as a whole.

What Is HALT Testing?

The requirements and standards for HALT testing may change from industry to industry and country to country. It’s important to understand which apply to you.

For the most part, however, the purpose and conditions of HALT remain the same. You’ll test products in extreme temperatures, humidity, with vibrations, and for corrosion if necessary (some also include dust build-up). In doing so, you can simulate the lifespan to discover weaknesses, find the point of failure, and establish expectations for users, including planned maintenance.

The tests vary depending on the product, and each is designed to alter conditions to mimic real-world stress. For example, a change of one or two degrees during the test could represent six months of time. So if you’d like to see if your product will last 15 years, you can design a test profile to do that.

Keep in mind, too, that HALT testing differs depending on the phase. In research and development, you determine when the product fails, what components in particular fail, and use the information to develop prevention measures. In production, you test to the point of that failure to ensure the product performs as intended.

Think of how crucial this is to a field like medical devices. You can advise with accuracy how long a defibrillator remains operational and when the user will need a new one. Patients getting knee replacements learn how effective the procedure is over time.

In addition to helping you set expectations for customers, HALT testing confirms all of the processes that lead up to your manufacturing. Any failures that follow it can reset your project, so be as thorough and diligent as possible.

What Is HASS Testing?

Highly accelerated stress screening is exactly what it sounds like. It involves pushing products to stress points, with different environmental conditions, identified during HALT testing. Companies differ on how they approach HASS testing based on their products. For example, manufacturers that produce something with a lithium-ion battery in it might test every single product because of the risk batteries pose to consumers. If even one is faulty, it could prove costly. The same is true of medical devices. The importance of these products justifies added attentiveness.

Other manufacturers do what’s called batch testing. They’ll run a random selection of products to confirm the results of their HALT testing.

HASS testing helps you spot defects or gives you confidence that you’re ready to get your products in the hands of consumers. It’s about gaining a full picture, not just of what you’re producing, but also how you’re producing it.

That’s only possible through a combination of HALT and HASS testing. You’ll develop a reputation as a company that operates efficiently and safely and keeps customers informed.


Associated Environmental Systems has designed, manufactured, and supported standard and custom test chambers to meet customers’ most demanding requirements for more than 60 years. Contact us for all your testing needs or view our inventory of test chambers here.