Page 170 - Design for Six Sigma a Roadmap for Product Development

Design for Six Sigma Project Algorithm 143

what the customer would like if the design entity was ideal. This con-
sideration of a product or service from a customer perspective must
address the requirements from higher-level systems, internal cus-
tomers (manufacturing/production, assembly, service, packaging, etc.),
external customers, and regulatory legislation. True attributes are not
directly operational in the world of the design teams. For this reason
it is necessary to relate customer attributes to the CTSs and then to
functional requirements that may be readily measured and, when
properly targeted, will substitute or assure performance to the true
quality of the attributes. The logic of a customer-to-design map is sev-
eral levels deep, and a tree diagram is commonly used to create such
logic (Cohen 1995).
In performing the mappings, the design team may start developing a
testing matrix for validation and continue updating it as more details
are achieved. They need to create tests that cover all customer attrib-
utes and eliminate unnecessary and redundant tests, specifically, a
testing hidden factory.

5.3.8 Define FR specification target values and
allowable variations (DFSS algorithm step 2)
Utilizing historical targets and variation provides an initial source of
information in this step. Competitive benchmarking, usage profiles,
and testing are useful tools to aid the DFSS team in understanding cus-
tomer usage and competitive performance. It is also important to
understand competition trends. The trend is vital because the team
should set the design targets to beat what the competition will release,
not what they have in the market now. On the basis of this information,
the DFSS team selects the appropriate test target and allowable varia-
tion for each test. This selection is based on the team’s understanding
of the relationship matrix in the QFD so that the appropriate values
may be chosen to satisfy design targets. Usually targets may be modi-
fied in light of customer studies. This involves verifying the target and
variation with the actual customers. In some occasions, surrogates
might be pieced together to measure customer reaction. In others, a
meeting with internal customers may be necessary. Targets are tuned,
and trade-off decisions are refined after assessing customer reaction.
The preliminary specification may now be written. The DFSS team will
select tests for the verification and in-process (ongoing) testing.
Step 2 actions are prerequisite to correctly proceed in the right path
according to the design project classification, namely, incremental or
creative. After mapping the classes of customer wants and needs to
their corresponding CTSs, the cross-DFSS team needs to map the CTSs
to FRs using the QFD methodology. The DFSS team then proceeds to
check the availability of datum solutions that address the array of FRs.