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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Wayne
Date posted: Fri Nov 29 10:37:21 US/Eastern 2002
Subject: MTBF or service life??
Message:
I often see supplier's specifications on things like for example a motor having an MTBF of 150,000hrs with a service life of 10 yrs. The MTBF greatly exceeds its service life. Is that possible? I thought that MTBF should be lower than service to make sense? So which figure do i use as my input for my reliability analysis of a complete system? MTBF or service life?


Reply:

Subject: Service Life
Reply Posted by: Joe Dzekevich (jdzekevich@ieee.org )
Organization: Raytheon RAL
Date Posted: Mon Dec 2 16:34:50 US/Eastern 2002
Message:
It will be interesting to see what other folks say. I read it as the motor has two failure rates - exponential and wearout. If I take 1/150K x 8760, that gives me a failure rate (returns rate) of 5.8% per year. I would then expect a 5.8% failure rate per year over a 10 year life. Now, they may have meant something else entirely.


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