Tag Archives: popular

Replacing MTBF with Bx

A Guest Post by Jim McLeish titled:

Replacing MTBF/MTTF with Bx/Lx Reliability Metrics 

Jim McLeish – Mid-West Regional Manager – DfR Solutions
(Rochester Hills Michigan)



Expanded from the RIAC Reliability Information Analysis Center Linkedin Group Discussion on

“Great challenge for change from Fred – No MTBF!”

“Endless discussion and it seems there’s no real solution to get rid of MTBF”

See original and ongoing Linkedin discussion here.


I am absolutely astonished that the reliability profession and its noted experts are unable to develop a better metric to characterize reliability performance and specify reliability requirements.  I respectfully submit that there is a simple and eloquent solution that has successfully been used in the ball bearing and machine industry for decades (that actually predates MTBF/MTTF), that should be considered as a replacement to MTBF/MTTF. Continue reading Replacing MTBF with Bx

MTBF: What is it Good For?

MTBF: What is it Good For?

Guest post by Andrew Rowland, CRE, ReliaQual Associates, LLC


The mean time between failure (MTBF) is arguably the most prolific metric in the field of reliability engineering. The MTBF is used as a metric throughout a product’s life-cycle; from requirements, to validation, to operational assessment. Unfortunately, MTBF alone doesn’t tell us too much. Continue reading MTBF: What is it Good For?

Where does 0.7eV come from

This post is a conversation first held on the LinkedIn group No MTBF. I’m capturing a portion of the contributions here to continue the discussion or to widen the audience. Reminds me of always assuming 95% confidence is the right value when designing a test, or assuming constant failure rate. So, let the conversation continue, starting with the original post. Continue reading Where does 0.7eV come from

The Worst Reliability Requirement

Most of us have seen reliability specified using a requirement like the following:

The Zeus 5000 SUV shall have an MTBF of 144,269.5 miles with a 90% confidence.

Some readers may not have seen reliability requirements specified in any other way.  What they have always seen has read something like:  The widget shall have an MTBF of X with a Y% confidence.  This reliability requirement structure is rather ubiquitous Continue reading The Worst Reliability Requirement

Why The Drain in the Bathtub Curve Matters

Most reliability engineers are familiar with the life cycle bathtub curve, the shape of the hazard rate or risks of failure of a electronic product over time. A typical electronic’s life cycle bathtub curve is shown in figure 1. Continue reading Why The Drain in the Bathtub Curve Matters