Thermal Shock Testing Liquid to Liquid Versus Air to Air Test Chambers

Author Information: Mary Babitz is the Vice President of Cascade TEK, an A2LA accredited environmental product testing laboratory. Thermal shock testing is one of many tests carried out in Cascade TEK’s two laboratories. In addition to product testing, they also manufacture high quality vacuum and laboratory ovens used for drying, curing and vacuum bake-out applications. Read more interesting facts about the science of product testing on their blog.

Thermal shock testing is performed to determine the ability of parts to withstand sudden changes in temperature. Thermal shock chambers rapidly move products between ”hot” and “cold” temperature zones many times to see the effects of thermal expansion and contraction (expansion with heat, contraction with cold). A thermal shock test generally means the transition from temperature extremes is done in five minutes or less.

There are a number of thermal shock testing profiles. Originating in the 1950’s, MIL-STD-202, Method 107 is generally understood to be the first of the thermal shock test profiles and the basis for the thermal shock test specifications of today. Some test specs specify using an “air to air” thermal shock chamber, while some specify using a “liquid to liquid” thermal shock chamber. MIL-STD 202, Method 107 allows for testing in both air to air and liquid to liquid chambers.

What are the differences?

Liquid to Liquid Shock Chambers have separately controlled hot and cold baths in an inert liquid (typically Galden). The liquid provides an excellent heat exchange rate, allowing the item under test to be moved very rapidly between temperature extremes and providing an immediate product temperature change. This is the key benefit. The liquid used in liquid thermal shock testing also does not coat the product or conduct electricity. The fluid, however, is very expensive and leakage and evaporation are always a possibility. Liquid to liquid chambers are also not as readily available as air to air chambers and are generally more expensive. Continue reading

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HALT/HASS Testing, what is it and why do I need to know about it?

By: Cincinnati Sub-Zero Products

What is HALT/HASS?

HALT, Highly Accelerated Life Tests and HASS, Highly Accelerated Stress Screens are environmental testing methods to help decrease production costs and increase profitability. These test methods are used to discover weak links in a new product that could cause failure in the field.  While HALT testing focuses on finding weak links and improving them during the design stage, HASS testing focuses of finding flaws during the production stage, and then working to fix those flaws.

In HALT testing, stimuli such as temperature, humidity, all-axis vibration etc. are used to accelerate stress on the product. Using these stimuli in combination, for example high temperature and all-axis vibration at the same time, are necessary in accelerating the time to failure.

With HASS testing, you then take the product during production and manufacturing and customize the screening of the product based on the individual product and how it performed during HALT testing.

So why do I need to know about HALT/ HASS testing?

If your company or organization implements HALT/HASS on a new product, its effect can produce substantial benefits across the life-cycle of your product. Continue reading

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What is Salt Spray Testing?

By: Hastest Solutions

A Salt Spray Test is an accelerated laboratory test providing a controlled corrosive environment to determine the rusting performance of a product in the field.

Salt Spray Testing is a requirement in a wide range of industries such as automotive, military, paint, and research institutions. It can be conducted on bare material as well as painted or coated material.

The well known ASTM-B117 salt spray test standard is commonly used. A solution of sodium chloride is sprayed at an angle between 15° to 30°. The temperature maintained within chamber is constant. The duration of test can be anywhere between 24 hours to 1,000 hours. Samples are rotated at regular intervals to allow even coating of the salt solution. The salt spray solution will put materials in a very harsh environment which will rust the surface and determine the result of damage inflicted by salt as well as a high chloride content. Continue reading

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Bigger Doesn’t Necessarily Mean Better

You would be surprised the variety of products that are tested for consumer and industrial use. Some items require large room-sized test chambers for testing. When it comes to smaller products such as cell phones or Continue reading

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Maintain Your Machine, Maintain Your Reputation

Thermal shock chambers are extremely complex and sensitive machines. They require the utmost care and attention in order to ensure that they are testing products properly and safely. Repair and maintenance on thermal test chambers must always be done by qualified technicians as the equipment Continue reading

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Testing, Testing, Testing

The world has become a much smaller place thanks to technology. Whether this is a good or bad thing depends on the individual that is asked, but what it does mean is times have changed. It is fairly easy to receive products from halfway around the world, simply by placing an order online. In fact, many of the products we receive are from far off places Continue reading

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