Case Study 2: Do you really understand your product’s reliability requirements?

A client  designs and manufactures sealed electronics units used in rugged environments.  The design team was working on a new product for a large customer.  It was similar to past products, with one difference – it had to pass a corrosion test that was different compared to previous tests.  As it turned out, the new corrosion test was more aggressive that the old tests.  However, this was unknown when the first set of prototypes were built using the same materials used in past products.  The prototypes failed the test when the seal degraded and leaked during exposure to the corrosion conditions.   Product verification tests were just a few months away and the customer was very concerned.

How would the materials engineering perspective prevent such a failure?

When faced with new design requirements some preliminary materials testing is helpful to verify the suitability of the materials and, if necessary, identify more suitable materials.  Ultimately, the goal is to reduce the risk of failing product tests and missing deadlines

In this case, simple and inexpensive preliminary screening experiments were performed to determine the suitability of the materials in the seal area and eliminate any underperforming alternatives.  Various coatings over the metal cover were evaluated for preventing the metal from corroding.  Cover screws with different alloy composition were evaluated.  In both cases, the tests were performed on tests samples rather than building product prototypes.  This kept costs low and sped up the process.  It also allowed us to evaluate several materials at once, rather than pinning our hopes on one solution.

Costs were also kept down by getting samples from the suppliers no cost.  The screening corrosion tests were performed by our client’s customer, at no cost.  Also, a visit to the one supplier provided even more insight into their process capabilities, which was used to refine the plan for how the housing could be fabricated.

The results from these and other tests helped us select materials that optimized the design by balancing cost, performance, and reliability. The product passed the next set of tests and the project was on track to meet its deadline.

Busted Myths

The design team learned that evaluating different materials options does not have to be expensive or turn into a complicated research project.  As it turned out the evaluations were inexpensive and simple.  Futhermore, the design team developed an appreciation for the need to proactively evaluate the effects of changes in product specifications on the reliability of materials, and not rely on intuition.