Six Sigma SPC - Statistical Process Control

Six Sigma SPC's Quality Control Dictionary and Glossary
2070 W. Washington St. #5 Springfield IL 62702  Ph: 217.698.0063
6 Sigma Statistical Process Control (SPC) Software for Windows 95/98/NT/2000/XP/ME


Home Search Capability Studies Links

Click Here!

Prices FAQ
About Support
Contact Quality Control Dictionary and Glossary Free Desktop 6 Sigma Calculator Forum
Quality Books Articles Free Online 6 Sigma Calculator Free Newsletter

MTBF - Mean Time Between Failure

A 'guesstimate' of the average, or mean time between design or component failure or disruption in the operation of the product, process, procedure, or design occurs. Mean time between failures assumes that the product can be repaired and the product can then resume itís normal operations. The repair of such a product is a non-value adding activity.

MTBF is not related with items like expected and/or operating life or other items that in general are not fixed or replacement even though it sometimes may be.

When a failure rate is unvarying, the likelihood that the product will perform without malfunctioning for a time that is equal to or greater than itís MTBF is only about 37%. This is due to the exponential distribution. A contradiction to the view that there is a 50-50, (or a 50% probability), chance of going beyond the MTBF.

Increases in MTBF may not necessarily result with a proportional rise in reliability. Example ...

MTBF of 5 = 82%
MTBF of 10 = .90%
MTBF of 100 = 99%.

MTBF is not the correct tool for all applications, but is a useful measurement of reliability.

Also see MTTF - Mean Time To Failure, Design Life, Durability, Expected Life, Failure Rate, and R Ė Reliability.

Back to the Quality Control Dictionary and Glossary

Click Here!


Copyright © 2005 Six Sigma SPC / Jim Winings All Rights Reserved
Privacy Statement - Disclaimer - Copyright - Site Map

Last Updated: Wednesday, 22-Mar-06 13:03:29 PST