Page 130 - Design for Six Sigma for Service (Six SIGMA Operational Methods)

Quality Function Deployment 105

In a typical service industry setting, QFD can be deployed in two phases, as
illustrated in Fig. 6.3.
QFD uses many techniques in an attempt to minimize and ease the task of
handling large numbers of functional requirements that might be
encountered. Applications in the range of 130 (functions) × 100 (customer
features) were recorded (Hauser and Clausing 1988). One typical grouping
technique that may be used initially in a QFD study is the affinity diagram.
The affinity diagram is a hierarchical grouping technique, which is used to
consolidate multiple unstructured ideas generated by the voice of the
customer. It operates based on intuitive similarities that may be detected
from low-level stand-alone ideas (bottom) to arrangements of classes of
ideas (up). This bundling of customer features is a critical step. It requires a
cross-functional team that has multiple capabilities such as the ability to
brainstorm, evaluate, and revolutionize existing ideas in pursuit of iden-
tifying logical (not necessarily optimum) groupings and, hence, minimizing
the overall list of needs into manageable classes.

Another technique is the tree diagram, which is a step beyond the affinity
diagram. The tree diagram is used mainly to fill the gaps and cavities not
detected previously in order to achieve a more completed structure leading
to more ideas. Such expansion of ideas will allow the structure to grow but
at the same time will provide more vision into the voice of the customer
(Cohen 1988).

The house of quality (Fig. 6.4) is the relationship foundation of QFD.
Employment of the house will result in improved communication,
planning, and design activity. This benefit extends beyond the QFD team to

Hows
CTS Operation
requirements variables

Whats Customer attributes House of Whats CTS requirements House of
quality
quality
1
2
Prioritized Prioritized
CTS operation
requirements variables

Figure 6.3 Multiple-Phase QFD in Service Application