Everybody Uses MTBF, Really?
When you say ‘… uses MTBF’? What is it you’re implying? Do they make important business decisions, or assess product designs, or order spares based on using MTBF?
When you use MTBF, what do you use it to accomplish?
- Do you write a report and send it to the requesting team?
- Do you run a calculation and provide the resulting MTBF to customers or vendors?
- Do you or anyone in your organization use MTBF in a useful manner.
And, if so, does it work for you? Does MTBF actually provide a useful metric related to your product’s reliability performance?
In my experience, MTBF and related metrics are great for meeting requirements or fulfilling requests, not much else. They are not useful for decision making. MTBF is next to useless when ordering spares. And, it is so commonly misunderstood that the report values are often simply misleading.
Do you receive request for MTBF from customers or internal teams? What do they use MTBF to accomplish? Check of as done?
Some may claim they use MTBF as a comparison to previous products. Some claim it provides an insights to the expected reliability performance. Some really do not know what do with MTBF so just ignore the value.
When gathering data for a part count prediction (aka Mil Hdbk 217 or similar) do you request MTBF values? Is so, do you also ask about failure mechanisms, derating parameters, or how/what will most likely fail?
Simply taking the MTBF value provided reinforces that notion that ‘everybody uses MTBF’ and does not provide you or your team useful information.
Data sheets, vendor websites, reliability reports, etc. all contain MTBF (sometimes called life, or reliability, yet the most common reported metric is MTBF or something similar).
MTBF is around us, built into tools, and expected. My contention is that even though it is not useful, it is so common, that it is assumed everybody uses MTBF.
Don’t be Everybody.
You will do a better job reporting reliability as couplets of probability of success and duration, rather than MTBF.
Do something that is useful and easy to use. Do not use MTBF. Be better than everybody. Add value to your organization, to your team, to your customers. Help others by your example, to be like you and not like everybody else.