Environmental testing refers to the measurement of performance of equipment under specified environmental conditions such as large, swift variations in temperature, solar radiations, extremely high or low humidity, corrosive conditions, among others which I will focus on later in details.
This, therefore, becomes a very important process in the research and development stage as it ensures that all products are of the best quality possible and are fully prepared for whatever conditions that will come their way in the real world.
Environmental testing is mostly carried out in environmental test chambers which are specifically built for this purpose and it is done either by independent testing laboratories or by manufacturers themselves.
During the testing, engineers can actually choose either to expose the products to established testing standards which specify the testing and climatic conditions or they can opt to come up with tailor-made test methods that are suited to the specific use and purpose of the product.
It has been regularly proven that those products that undergo environmental testing perform much better compared to those that do not go through the test.
The following are the types of environmental test programs that are available.
1. Temperature and humidity testing.
This testing is done so as to determine how the products will behave in severe environments that will involve high moisture and temperature
This kind of testing is carried out in environmental chamber that is designed to simulate the extreme conditions.
This testing is done so as to determine how the products will behave in severe environments that will involve high moisture and temperature.
This test can be conducted with constant temperature and humidity, they can include cycling test of both parameters, or just either one.
This test enables the engineers to evaluate product’s reliability and survival temperature by accelerated thermal changes inside the chamber.
We had discussed about how to choose the right temperature and humidity previously.
2. Sudden and extreme temperature variations testing (thermal shock)
These kinds of tests are also known as thermal shock tests and are performed on products so as to determine their resistance to sudden changes in temperature.
The parts being tested undergo a specified number of cycles which the parts are suddenly exposed to extremely high and low temperature alternatively.
After the final cycle is completed, the parts being tested undergo an external visual examination that is meant to determine if any damage occurred during the testing process.
Electrical testing of the samples is also conducted so as to detect electrical failures accelerated by the thermal shock cycling test.
Since thermal expansion rate of different materials often varies, thermal shock testing can cause failures that are not possible with mechanical means.
The test, therefore, helps to identify weak elements which greatly help to enhance the overall product reliability.
A detailed article explaining Thermal Shock Test is published in previous blog.
3. Moisture or humidity testing
Humidity testing is done so as to accelerate the aging of products that are easily affected by ambient moisture levels.
Increasing humidity above the normal levels can cause defects and failures in products in a shorter period of time that it would have been normally observed in the field.
Conducting this kind of tests can help to mitigate issues such as mechanical failures, corrosion, electrical shortages, among many others.
4. Corrosive atmosphere testing (salt spray test)
An ideal example of an accelerated corrosive test is the salt spray testing which produces a corrosive attack on coated samples so as to evaluate the suitability of the coating for use as a protective coating.
Salt spray test is usually carried out on metallic materials so as to check out their rate of degradation under corrosive conditions.
In this test, the samples are exposed to a corrosive condition in testing chamber after which several measurements are taken so as to determine the impact on the sample’s surface coating.
There is always a question asking: “How does the Salt Spray Test hours correlate with real-world duration?”
There is not conclusion or definite answer for this question, you may read our previous article about this topic here.
The test for X hours is not an indicator of any number of years that coating will resist corrosion. This is because, in real life situations, rust takes years to occur. So the best thing is to take this test only as a predictor of real-world outcomes
5. Sand and dust testing
This kind of testing is especially important for electronics that are used in military ground vehicles and other delicate applications.
The testing is mostly conducted during device development and evaluation stage so as to check its reliability relative to atmospheric effects from dust and sand particles.
The samples are tested by being put in dust and sand chambers which circulate the sand and dust within a wind tunnel.
During the testing, the fine particles get into any cracks or small gaps of equipment, which lead to different kinds of failure to the equipment.
6. Solar testing
This kind of testing is also referred to as UV exposure, accelerated weathering test, or even solar radiation test.
Solar radiation test is performed on products that are meant to be exposed to direct sunlight for long periods. The tests replicate the damage that is caused by sunlight, together with rain and dew in a UV lamp or xenon arc chamber.
We have an blog post explains the different of QUV Chamber and Xenon Arc Chamber.
Sample can be put through damage caused by months or even years of exposure to direct sunlight by running this test just for few days or weeks.
As illustrated in one of our article “How Long Do I Have to Carry Out Accelerated Weathering Testing to Simulate X Years of Outdoor Exposure?”, it is impossible to figure out a formula that relate the aging time in test chamber and real-world/outdoor exposure.
...outdoor exposure can be varied by geographical local, altitude, season, atmosphere, environment and many other factors. Therefore, it is impossible to figure out a formula that relate the aging time in weatherometer and outdoor exposure
Solar radiations are meant to serve two purposes which are; to determine heating effects from sunlight impinging directly on equipment for a long period of time and identifying material degradation from radiation of sunlight.
In order to replicate outdoor weathering perfectly, the accelerated weathering test chamber exposes the samples to pre-set cycles of UV light, with controlled temperatures and humidity.
7. Other environmental tests
There are other environmental tests that involve rain, altitude or low pressure, high pressure, vibration, ozone resistance and other climatic effects.
Sometimes, engineer combine environmental test (for example temperature and humidity test) with vibration and shock test for a more closer imitation to real-world circumstance where the product is used.
Benefits of Environmental Testing
Clearly, environmental testing is very important process for engineers to determine potential weakness and hazards of their product before it enters to markets.
Climatic testing is always demanded by industries related to military, aerospace, automotive and electronic devices as this is a prerequisite in purchasing contract.
By going through a series of testes, the engineers are able to determine the possible failure modes under specific environmental condition, which helps them to find the remedy and improve overall product quality.
In return, environmental testing eliminates product risk and business liability
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