Page 249 - Design for Six Sigma a Roadmap for Product Development

Quality Function Deployment (QFD) 219

7.4.1 Customer attributes (WHATs)
These are obtained from the voice of customer as represented by surveys,
claim data, warranty, and promotion campaigns. Usually customers use
fuzzy expressions in characterizing their needs with many dimensions
to be satisfied simultaneously. Affinity and tree diagrams may be used
to complete the list of needs. Most of these WHATs are very general
ideas that require more detailed definition. For example, customers
often say that they look for something “stylish” or “cool” when they
purchase a product. “Coolness” may be a very desirable feature, but
since it has different interpretations for different people, it cannot be
acted on directly. Legal and safety requirements or other internal wants
are considered extensions to the WHATs. The WHATs can be character-
ized using the Kano model (Sec. 7.5).

7.4.2 HOWs
The design features derived by the DFSS team to answer the WHATs
are called the HOWs. Each initial WHAT requires operational defini-
tions. The objective is to determine a set of critical-to-satisfaction
(CTS) requirements with which WHATs can be materialized. The
answering activity translates customer expectations into design crite-
ria such as speed, torque, and time to delivery. For each WHAT, there
should be one or more HOWs describing a means of attaining customer
satisfaction. For example, a “cool car” can be achieved through a “stylish”
body (different and new), seat design, legroom, lower noise, harshness,
and vibration requirements. At this stage only overall requirements
that can be measured and controlled need to be determined. These
substitute for the customer needs and expectations and are tradition-
ally known as substitute quality characteristics. In this book, we will
adopt the critical-to terminology aligning with Six Sigma.
Teams should define the HOWs in a solution-neutral environment
and not be restricted by listing specific parts and processes. Itemize
just the means (the HOWs), from which the list of WHATs can be
realized. The one-to-one relationships are not the real world, and
many HOWs will relate to many customer wants. In addition, each
HOW will have some direction of goodness or improvement of the
following:

Direction of Improvement
Maximize 1.0
Target 0.0
Minimize –1.0

The circle represents the nominal-the-best target case.