FEATURE TEST & MEASUREMENT
SIMULATING THE ENVIRONMENT FOR PRODUCT RELIABILITY
Craig Foster, manager for environmental testing at TÜV SÜD Product Service, a global product testing and certification organisation considers the environmental variables that effect product reliability testing
roduct reliability testing has become an important part of the design process as end-users are increasingly demanding products that are more reliable, have a longer life and deliver value for money. The term ‘reliability’ is defined as “the
P
ability of an item to perform a required function under stated conditions for a stated period of time”. The ‘required function’ includes the specification of satisfactory operation as well as unsatisfactory operation, while for a complex system, unsatisfactory operation may not be the same as failure. The ‘stated conditions’ are the total physical environment including mechanical, thermal and electrical conditions. The ‘stated period’ of time is the time during which satisfactory operation is desired and is often called the service life of a product. The link between product quality and
environmental testing is obvious as it helps to ensure that it will not degrade and continues to fulfil its purpose when exposed to a range of adverse conditions that would be expected in normal use. To maintain brand loyalty, it’s therefore vital to test the product to ensure that it survives the in-use environment. Environmental testing can therefore help to strengthen a brand’s competitive position in the market due to improved product performance and reliability by reducing the chances of failures in use.
WHAT IS ENVIRONMENTAL TESTING? You can only simulate and not replicate an environment into which a product will be put. That is because there are so many variables, so while environmental testing can give confidence in a product’s reliability, extra unknown factors may come into play in the real world. For example, while you may have tested for a humid environment, you may not have anticipated that one particular user would leave the product in the sun for long periods of time, before rain rapidly cools it. Humidity, solar and cooling effects are therefore difficult to 100% accurately anticipate for each specific end-use situation.
14 MAY 2018 | ELECTRONICS
this – such as RTCA/DO-160, which outlines environmental conditions and test procedures for civil avionics, and the USA military environmental testing standard, MIL-STD-810. However, as BS EN 60068 is not market or product specific, it is a useful tool to tailor environmental tests specific to each individual product need. Manufacturers can therefore test according to their customers’ specific end-use requirements, or take the acquired data approach – simulating the specifics of the intended environment. The simulation of the environment
Generally there are two types of
environmental testing that are undertaken – reactive and proactive. Proactive testing is ideal, as without the ability to gauge reliability throughout the design lifecycle there is no assurance that the final product will meet market expectations. Redesigns further down the design process, or in response to product failures once it has been released onto the market, are more costly than proactively testing a product for possible environmental concerns early on. Therefore, not only should designers take into account normal operating conditions, but also foreseeable misuse and external environmental influences. Reactive testing is normally in response to the failure of a product once it is on the market, warranty returns, or a customer complaint – not the ideal situation. This can be more common than you think as due to there being so many variables, it is sometime impossible to cover all possible environmental situations. A product can let the manufacturer down if they have not ensured that they are fully aware of the environment expected, or the end- user surprising you through misuse of the product.
BS EN 60068-2 is a general standard
which gives guidance on how to conduct environmental testing. Meanwhile, many industry sectors also have their own specific requirements which sit alongside
Figure 1:
Craig Foster, manager for environmental testing at TÜV SÜD Product Service
during tests therefore helps to predict failure levels. For example, a low temperature can increase fluid viscosity, impact gases, cause materials to fail, or parts to bind due to differential contractions of unlike materials.
BEYOND THE TICK-BOX The link between product quality and environmental testing is obvious, as the features and characteristics of a product determine its desirability. If these features do not degrade and the product continues to fulfil its purpose when exposed to a range of adverse conditions, especially those that would not be expected in normal use, a lasting belief in the product’s quality is formed. Thus performing environmental testing to ensure that the product maintains its desirable features when exposed to adverse conditions will support brand loyalty. However, many designers make the
mistake of thinking that ensuring products comply with mandatory tests set out in product standards is enough. But, for many products there are no specified environmental test requirements, and testing should therefore not be a ‘tick-box’ exercise. Using environmental testing to understand the impact of the unexpected during the product development stage will therefore future- proof developments, creating a robust and user-friendly product.
TÜV SÜD
www.tuv-sud.co.uk/uk-en T: (0)1489 558100
/ ELECTRONICS
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