MTBF interpretation 1

[Metera]

Hello,
If MTBF value is 120 yrs, and 7 units failed out 1200 units, how is this translated in to ppm or % wise?
Regards

 

[kchan711]

MTBF is not exactly the right value for predicting the number of failures of a certain amount of units. You'll need to figure the actual probable failure rate to figure failures of parts per million.

MTBF will allow you to predict the probability of a part working based on a certain time. R(T)=exp(-T/MTBF) T is the time you're interested in and R(T) is the probability the part will work over that course of time.

Hope that helps answer part of your question.

- Kyle

Kyle Chandler

http://www.chiefengineering.net

"To the Pessimist, the glass is half-empty. To the Optimist, the glass is half-full. To the Engineer, the glass is twice as large as it needs to be!"

 

[conrad89]

What is your physics of failure, is exponential the correct distribution? I agree with the Kyle, you will need to calculate reliability at a given time to get ppm.

 

[IRstuff]

You need to also determine whether the MTBF is predicted for the same environmental conditions that the systems that failed were operating in.

A higher ambient temperature could easily double or quadruple the failure rate.

TTFN

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