Explain Bathtub Curve and its utility in reliability engineering. Is this concept applicable for all products?
My interpretation : Mostly used in New Product to the Market offerings : Eg : Air Purifiers, Hotel Baking Industry machine new model or a simple NEW to market Coffee Maker.
For simple reasons of Product Stabilization 1) The Early stage failures would be high. As they get fixed gradually one after another, the 2) Random/Natural usage based defects popup. Some of these can be solved via quick fixes and some need a product design modification or intervention.
Eventually, as the product moves into the 3) Last 1/3rd phase of it's expected life, brands will start receiving breakdown complaints due to the parts that end up wearing off faster than anticipated. The first wave, if addressed, the product's "Usable Life Span" can be validated/improved.
The final set to wear off, usually are not aimed for reeingineering as the investment could mean a significtant markup in the production costs.
In some ways, this also applies to new service offerings : Eg : Hotels introducing new Cuisine / SPA services etc. The learning curve here helps in maturing the offerings and the last section may not be applicable as in service lines, the improvement in service is a "Continuous Improvement" journey. One way UP !!
Note : The image from wikipedia can act as a good pictorial representation.