Reliability and Durability

[McKofi]

I am just new in reliability, I want to be a reliability engineer in the future.

Could you please explain to me the difference between Reliability and Durability.

Thanks,

[Pantelis]

Well it’s a good question, and one that I do not believe that you will get a clear cut answer on. Here is my five cents. Both deal with the probability of success – it really comes down as to what one considers in the analysis (along with what definition one uses for each).

A general definition of Reliability is: Reliability engineering provides the theoretical and practical tools whereby the probability and capability of parts, components, equipment, products and systems to perform their required functions for desired periods of time without failure, in specified environments, and with a desired confidence can be specified, designed in, predicted, tested and demonstrated.

As for durability “Durability relates to both personnel and equipment, along with the environment within which they operate”

Now is there an overlap between the two definitions. Yes. One can include human, as well as environmental reliability factors in their analysis, and they will still be doing classical reliability…

Personally I believe that reliability is all encompassing and introducing new terms such as durability just confuses the issue, of course that’s just a personal opinion.

[Walmsley]

In the auto industry,we tersely consider Reliability to be the useful life of Quality and Durability to be the useful life of Reliability. i.e. The "Durability" point is that point which demonstrates an IHR for the theoretical bathtub curve.

Something to be cognizant of is that,yes, there are certainly instances where the Durability point can appear quite early. This is especially true where inadequate resources are dedicated to a major product change in a project.