"Your Guide for FMEA Information"
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A Functional Approach to FMEA
Functional FMEA - When performing a design FMEA there are various ways in
which you can approach the system that you are analyzing. The system tree or
project tree that you set up for performing the FMEA can mimic your hardware,
functions, interfaces or a combination of these things.
which you can approach the system that you are analyzing. The system tree or
project tree that you set up for performing the FMEA can mimic your hardware,
functions, interfaces or a combination of these things.
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FMEA RPN
What is FMEA?
How FMEA is Done
Types of FMEA
Benefits of FMEA
FMEA Books
FMEA Software
FMEA Examples
Other Resources
FMEA RPN
This functional FMEA approach can still provide us with the information that we
need, but the analysis can possibly be conducted in a fraction of the time
involved with the piece-part approach. This same approach might be used for
interface functions, memory, input/output or other types of functions.
The top level board functions that we are modeling in our FMEA would have
failure rates assigned to them that correspond to the failure rates of the parts or
portion of parts that contribute to the function. Some of the better FMEA tools on
the market even have a means to easily link functions in the FMEA to parts or
portions of parts in their reliability prediction. This way as the reliability prediction
is updated the analyst can quickly refresh the failure rates associated with the
functions defined in the FMEA. Obviously, if any of the functions have failure
modes resulting in critical effects, then the analyst would most likely take a closer
look at the parts involved in the critical function.
Hopefully, this information on functional FMEA has been helpful, and has started
you thinking of other ways that this powerful analysis technique can be used in
assessing your designs.
need, but the analysis can possibly be conducted in a fraction of the time
involved with the piece-part approach. This same approach might be used for
interface functions, memory, input/output or other types of functions.
The top level board functions that we are modeling in our FMEA would have
failure rates assigned to them that correspond to the failure rates of the parts or
portion of parts that contribute to the function. Some of the better FMEA tools on
the market even have a means to easily link functions in the FMEA to parts or
portions of parts in their reliability prediction. This way as the reliability prediction
is updated the analyst can quickly refresh the failure rates associated with the
functions defined in the FMEA. Obviously, if any of the functions have failure
modes resulting in critical effects, then the analyst would most likely take a closer
look at the parts involved in the critical function.
Hopefully, this information on functional FMEA has been helpful, and has started
you thinking of other ways that this powerful analysis technique can be used in
assessing your designs.
For example, let's take a look at how we
might approach the FMEA for a circuit card
assembly (CCA). One approach might be to
perform a piece-part level FMEA where
we look at ways in which the CCA might fail
and its effect on the rest of our system.
Then, we could look at how each part is
most likely to fail and the resulting effects of
each of these part failure modes on the
CCA. A good resource when identifying
piece-part failures is the Reliability
Analysis Center's FMD-97 Failure Mode
Distributions guide. Obviously, if our CCA
has very many parts this hardware
approach could become very tedious and
time consuming. For instance, we could
have many capacitors on our board, each
with several failure modes, which possibly
result in the same effect on our CCA.
Although this approach is quite thorough,
much of this repetitive effort may not give
us a great return for the time spent.
might approach the FMEA for a circuit card
assembly (CCA). One approach might be to
perform a piece-part level FMEA where
we look at ways in which the CCA might fail
and its effect on the rest of our system.
Then, we could look at how each part is
most likely to fail and the resulting effects of
each of these part failure modes on the
CCA. A good resource when identifying
piece-part failures is the Reliability
Analysis Center's FMD-97 Failure Mode
Distributions guide. Obviously, if our CCA
has very many parts this hardware
approach could become very tedious and
time consuming. For instance, we could
have many capacitors on our board, each
with several failure modes, which possibly
result in the same effect on our CCA.
Although this approach is quite thorough,
much of this repetitive effort may not give
us a great return for the time spent.
A common approach used in this situation is to model the CCA functionally, so
that the top level functions that the circuit card performs are listed instead of the
components. Each function represents a group of parts or portions of parts,
which contribute to the function. We then list the failure modes that are
applicable to the function and the effects these failure modes have on the CCA.
that the top level functions that the circuit card performs are listed instead of the
components. Each function represents a group of parts or portions of parts,
which contribute to the function. We then list the failure modes that are
applicable to the function and the effects these failure modes have on the CCA.
For example, let's say that we have 20
decoupling capacitors involved in our
design, whose failures result in the same
effect on the CCA. In this case, we could
define a single function in our analysis
tree called Decoupling Capacitors. We
would then define the failure modes
associated with this function and their
effects on the CCA. In this simple case,
we have one function with three failure
modes to analyze instead of 20
capacitors, each with three failure
modes.
decoupling capacitors involved in our
design, whose failures result in the same
effect on the CCA. In this case, we could
define a single function in our analysis
tree called Decoupling Capacitors. We
would then define the failure modes
associated with this function and their
effects on the CCA. In this simple case,
we have one function with three failure
modes to analyze instead of 20
capacitors, each with three failure
modes.