Mean
Time Between Failure(Quality management term)
There is no previous definition.
MTBF stands for mean
operating time between failures (wrongly mentioned as mean time between
failures throughout the literature) and is used as a reliability measure for
repairable systems. In British Standard (BS 3527) MTBF is defined as follows:
For a stated period
in the life of a functional unit, the mean value of the lengths of time between
consecutive failures under stated condition.
MTBF is extremely
difficult to predict since it depends on several factors such as operating
conditions, maintenance and repair effectiveness etc. In fact, it is very
rarely predicted with an acceptable accuracy.
Charesteristics of
MTBF:
1. The value of MTBF is equal to mean time to failure
(MTTF) if after each repair the system is recovered to as good as new.
2. MTBF=1/λ for exponential distribution, where λ is
the scale parameter (also the hazard function).
Applications of MTBF:
1. For a repairable system, MTBF is the average time in
service between failures. Note that, this does not include the time spent at
repair facility by the system.
2. MTBF is used to predict steady-state availibility
measures like inherent and operational availability.
(Dinesh Kumar,U. Dinesh Kumar, Reliability And
Six Sigma, pages 95-98)
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