While Six Sigma methodologies are typically more process related rather than product related, but there are indeed tools that can be useful. Within the quality engineering book of knowledge, there is a whole segment on reliability. Certainly, Weibull analysis and the bathtub curve is the direct way to address product durability, but they are not typically included in a list of “six sigma tools”
But the six sigma tools that focus on understanding variation are worthy of inclusion in the product development process.
- Creating a cause & effect diagram for the part can be useful for discussions about how to reduce the variation.
- A good Failure Modes Effect Analysis(FMEA) can aid in developing the production process for the part, again with the intent of reducing variation.
- Finally, I would suggest Fault Tree Analysis would be useful to aid in predicting failure rates.