Design Failure Rates - Mechanical
Design Failure Rates - Mechanical
(OP)
How are design failure rates determined for equipment that is produced? I know that this is a rather broad question, but this is not my field. Thanks, any assistance would be greatly appreciated.





RE: Design Failure Rates - Mechanical
TTFN
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RE: Design Failure Rates - Mechanical
Usually, I got trouble enough just getting it to last through the warranty period.
Mike Halloran
Pembroke Pines, FL, USA
RE: Design Failure Rates - Mechanical
RE: Design Failure Rates - Mechanical
MikeHalloran,
Based on my personal experience, I would disagree with your comment. I work in aerospace, and we do analysis for both failure rates and modes. A failure rate analysis is usually just a straight forward statistical calculation, based on historical failure rates for each given component in a system. It's uncanny how accurate they usually are.
RE: Design Failure Rates - Mechanical
I think MikeHalloran is in the same world as I am ...
RE: Design Failure Rates - Mechanical
I'm asking the question in general, and I guess by your answers I can see that it all depends.
Thanks for the replies, much appreciated.
RE: Design Failure Rates - Mechanical
RE: Design Failure Rates - Mechanical
In terms of structural materials, you have the manufacturer's material specifications, and you make a trade between how much you allow the material to be stressed, and how much cost or weight you can tolerate. Just bear in mind that no one is willing to pay for, in cost or weight, a system that will never fail.
TTFN
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RE: Design Failure Rates - Mechanical
Mike Halloran
Pembroke Pines, FL, USA
RE: Design Failure Rates - Mechanical
I'm certainly no kind of expert, only had some exposure to it with a former company and our products. Our product was an industrial device advertised as "20,000 hours MTBF". But one customer challenged that and demanded to know what the heck that meant, and how the data was derived. Research with the Engineering Department showed that they had tabulated "whatever data was available" for all the myriad components that made up the device. Then they somehow magically came up with "20,000 hours" as MTBF. Further investigation determined that the 20K hours was for "maximum loading and duty cycle" of the device. If the loading and duty cycle were less (it ALWAYS was), then the 20K value increased. But then again, there was no real value to quote the customer for max MTBF. Now, after several years of data under their belts, the company quotes 80,000 hrs MTBF.
MTTR is the time to repair / replace a component, and has stayed static due to component choices.
TygerDawg
Blue Technik LLC
Advanced Robotics & Automation Engineering
www.bluetechnik.com
RE: Design Failure Rates - Mechanical