Failure Mode and Effects
Analysis (FMEA) was one of the first systematic techniques for failure
analysis. It was developed by reliability engineers in the 1950s to study
problems that might arise from malfunctions of military systems. A FMEA is
often the first step of a system reliability study. It involves reviewing as
many components, assemblies, and subsystems as possible to identify failure
modes, and their causes and effects. For each component, the failure modes and
their resulting effects on the rest of the system are recorded in a specific
FMEA worksheet. There are numerous variations of such worksheets. A FMEA is
mainly a qualitative analysis.
A few different types of FMEA
analysis exist, like
- Functional,
- Design, and
- Process FMEA.
Sometimes the FMEA is called FMECA to indicate
that Criticality analysis is performed also.
An FMEA is an Inductive reasoning (forward logic) single
point of failure analysis and is a core task in reliability engineering, safety engineering and quality engineering. Quality engineering is
specially concerned with the "Process" (Manufacturing and Assembly)
type of FMEA.
A successful FMEA activity helps
to identify potential failure modes based on experience with similar products
and processes - or based on common physics of failure logic. It is widely used
in development and manufacturing industries in various phases of the product
life cycle. Effects analysis refers to studying the consequences of
those failures on different system levels.
Functional analyses are needed
as an input to determine correct failure modes, at all system levels, both for
functional FMEA or Piece-Part (hardware) FMEA. A FMEA is used to structure
Mitigation for Risk reduction based on either failure (mode) effect severity
reduction or based on lowering the probability of failure or both. The FMEA is
in principle a full inductive (forward logic) analysis; however, the failure
probability can only be estimated or reduced by understanding the failure
mechanism. Ideally this probability shall be lowered to "impossible to
occur" by eliminating the (root) causes. It is therefore important to
include in the FMEA an appropriate depth of information on the causes of
failure (deductive analysis).
