A few months ago at a IEC Dependability standards meeting, I met Thomas Young Olesen of Grundfos and we talked a little about NoMTBF. He said their company has a polity to not use MTBF. YES! So I asked for permission to post some information about the policy.
One interesting part of their internal site was a MTBF Calculator.
This is just a screen shot, yet by clicking the “I’m feeling lucky” link to get a new number. There is a short animation of rolling numbers (ala slot machine) and a new number appears. I’m told is a random number generator behind the scenes and suitable substitute for MTBF – given they are rather meaningless to begin with.
I like this company and this policy.
Thomas also sent me a short slide set that explains the policy a little more conventionally.
Does your company have such a policy? If so, please ask for permission to share here and lauded as one of the enlighten companies of the NoMTBF era. If not, why not?
I wrote the article on Grundfos’ Intranet after someone used 3000 Euro of the company money buying a MTBF. They might as well have burned them 🙂
Then we added the slides in order to give a serious touch to what was actually started as a joke for April 1st. That made it possible for the document to survive, and we now have a clear statemet about MTBF policy – No MTBF policy, it is.
The 3000 Euro (4050 dollars) expensive MTBF report stated a 10% cummulated failure rate after 14 years. But then, in the chapter Notes, it was written:
“Electrolytic capacitors (….) and fan show, in addition to the random failures, a wear-out failure mode, which has effect significantly earlier than for the other components.
According to well-known manufacturers the wear-out of electrolytic capacitors has effect after about 10 to 15 years depending on operating conditions (….)
The fan used has according to data sheet a 10% failure-life of 2.3 years at
70° C.”
My conclusion is that the MTBF is meaningless. The fan is needed, and if it fails after two or three years then the whole machine fails.