Pitfalls of Reliability Allocation
Join Carl and Fred as they discuss what works and what does not work when allocating reliability from system to lower levels.
- Don’t assume every component has the same impact on overall system performance
- Beware of inaccurate assumptions
- Allocation can become a numbers game
- Factor in current reliability and capability
- Remember the four elements of reliability
- MTBF versus probability
- Reliability goals versus reliability requirements
- Updating the system reliability model during product development
- Using the system reliability model to prioritize where to focus
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[Excerpt from paper titled ” Integrating R&M into Early Stages of Design Process”, by Carl Carlson]
Reliability Allocation can be a useful method to roll down requirements to corresponding subsystems and components, provided one understands the assumptions that are involved and the common mistakes that are made. The following are some of these pitfalls that must be taken into account if Reliability Allocation is to be used successfully.
Pitfall # 1
Believing that the allocated numbers have value by themselves (a “numbers” game), distracting people from needed Reliability tasks.
Pitfall # 2
Making inaccurate assumptions (such as exponential distribution) in order to facilitate the allocation procedure.
Pitfall # 3
Treating Reliability as a GOAL, rather than a requirement that is measurable during product development.
Pitfall # 4
Over emphasizing and over testing low priority areas, with resultant waste of resources.
Pitfall # 5
Under emphasizing and under testing critical priority areas, resulting in undetected problems.
Pitfall # 6
Providing Reliability targets for suppliers that are significantly lower than world class.
Pitfall # 7
Believing that Reliability does not have to be engineered into the product or process. (This is the biggest mistake of all)