Page 56 - Six Sigma for electronics design and manufacturing

Six Sigma for Electronics Design and Manufacturing
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1.11.2 Failure modes and effects analysis (FMEA)
FEMA provides a formal mechanism for resolving potential problems
in a product, system, or manufacturing process. It is a structured ap-
proach to identifying the ways in which products, systems, or process-
es can fail to meet customers’ requirements by:
1. Estimating the risk of specific causes of the failures
2. Evaluating the control plan for preventing the failures from occur-
ring
3. Prioritizing the actions taken to improve the product or process
FMEAs can be performed by teams focused on solving problems in
systems, designs, or manufacturing processes. The teams should also
perform process mapping of the product, process, or system to be ana-
lyzed. The types of FMEAs that can be performed are:
1. System FMEA: Performed in order to analyze systems and their
subfunctions in the early concept and design stages. It should be
started after systems functions are completed but before detailed
design is initiated.
2. Product Design FMEA: Performed on products before they are re-
leased to manufacturing. It should be started after product func-
tionality is defined and completed prior to release to manufactur-
ing.
3. Manufacturing FMEA: Performed to analyze manufacturing, as-
sembly, and transaction processes started when preliminary draw-
ings are released. This activity should be ongoing, completed only
when the product is obsolete.

1.11.1.2 FMEA process. The FMEA methodology begins with identify-
ing each element, assembly, or part of the process, and listing the po-
tential failure modes, potential causes, and effects of each failure. A
risk priority number (RPN) is calculated for each failure mode. It is
an index used to measure the rank importance of the items listed in
the FMEA chart. These conditions include the probability that the
failure takes place (occurrence), the damage resulting from the failure
(severity), and the probability of detecting the failure in-house (detec-
tion). High RPN items should be targeted for improvement first. The
FMEA analysis suggests a recommended action to eliminate the fail-
ure condition by assigning a responsible person or department to
resolve the failure by redesigning the system, design, or process and
recalculating the RPN.