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390 Chapter Eleven

11.2 FMEA Fundamentals
An FMEA can be described as a systemic group of activities intended to

1. Recognize and evaluate the potential failures of a product or
process and the effects of that failure
2. Identify actions which could eliminate or reduce the chance of the
potential failure occurring
3. Document the entire process

It is complementary to the process of defining what a design or process
must do to satisfy the customer (AIAG 2001).
In our case the process of “defining what a design or a process must
do to satisfy the customer” is the DFSS algorithm. The DFSS team
may visit existing datum FMEA, if applicable, for further enhance-
ment and updating. In all cases, FMEA should be handled as a living
document.The fundamentals of an FMEA inputs are depicted in Fig. 11.2
and the following list:
1. Define scope, the FRs or DPs, and process steps. For the DFSS
team, this input column can be easily extracted from the physical and
process structures or process mappings. However, we suggest doing
the FMEA exercise for subsystems and components identified in the
structures according to the revealed hierarchy resulting from the
zigzagging method. At this point, it may be useful to translate the phys-
ical structure into a block diagram like the one depicted in Fig. 11.3 for
an automotive engine. The block diagram is a pictorial translation of
the structure related to the FMEA of interest. The block diagram
strengthens the scope (boundary) of the FMEA in terms of what is
included and excluded. In DFMEA, for example, potential failure
modes include the delivery of “No” FR, partial and degraded FR deliv-
ery, over time, intermittent FR delivery, and unintended FR (not
intended in the physical structure). The physical structure should help
the DFSS team trace the coupling and with the help of the block dia-
gram, pictorially classifies the coupling among the FRs in terms of
energy, information, or material (Pahl and Beitz 1988).
2. Identify potential failure modes. Failure modes indicate the loss of
at least one FR. The DFSS team should identify all potential failure
modes by asking “In what way does the design fail to perform its FRs?”
as identified in the physical structure. Failure modes are generally
categorized as material, environment, people, equipment, methods, and
so on. Failure modes have a hierarchy of their own, and a potential
failure mode can be the cause or effect in a higher-level subsystem,
causing failure in its FRs. A failure mode may, but not necessarily must,